阅读说明：本技术 挤出帘线加强的轮胎部件的挤出机和方法 (Extruder and method for extruding cord reinforced tire components ) 是由 R·乌普斯 I·古登 G·穆尔德 于 2016-01-06 设计创作，主要内容包括：本发明涉及用于挤出帘线加强的轮胎部件的挤出机和方法,其中挤出机包括具有模具和帘线引导件的挤出机头部,其中模具设置有横截面轮廓,该横截面轮廓限定了模具中的挤出材料的第一横截面,其中所述横截面轮廓具有轮廓高度,其中帘线引导件布置成用于在帘线进入高度处将帘线引导到模具中,其中挤出机头部设置有第一加热元件,其中挤出机包括控制单元,其操作地连接到第一加热元件,用于在轮廓高度上产生挤出材料中的可调节的高度温度梯度,以在挤出材料离开模具之后控制挤出材料相对于帘线进入高度从第一横截面到第二横截面的膨胀。(The present invention relates to an extruder and a method for extruding a cord-reinforced tire component, wherein the extruder comprises an extruder head with a die and a cord guide, wherein the die is provided with a cross-sectional profile defining a first cross-section of the extruded material in the die, wherein said cross-sectional profile has a profile height, wherein the cord guide is arranged for guiding the cord into the die at a cord entry height, wherein the extruder head is provided with a first heating element, wherein the extruder comprises a control unit operatively connected to the first heating element for generating an adjustable height temperature gradient in the extruded material over the profile height for controlling the expansion of the extruded material from the first cross-section to a second cross-section relative to the cord entry height after the extruded material leaves the die.)

1. An extruder with an extruder head for extruding a cord-reinforced tire component, wherein the extruder head comprises a die for receiving an extruded material and a cord guide for guiding the cord into the die such that, in use, the cord is embedded in the extruded material, wherein the die is provided with an elongated cross-sectional profile defining a first cross-section of the extruded material in the die, wherein the cross-sectional profile has a profile width and a profile height which is smaller relative to the profile width, wherein the cord guide is arranged for guiding the cord into the die at a cord entry height relative to the profile height, wherein the extruder head is provided with one or more first heating elements arranged to transfer heat from a first side of the profile height into the extruded material, wherein the extruder further comprises a control unit operatively connected to the one or more first heating elements, for creating an adjustable height temperature gradient in the extruded material over the profile height for controlling the expansion of the extruded material from the first cross section to the second cross section relative to the cord entry height after the extruded material exits the die, wherein the one or more first heating elements comprise a plurality of first heating elements distributed over the profile width, wherein the control unit is arranged for individually controlling the temperature of each of the plurality of first heating elements over the profile width.

2. Extruder according to claim 1, wherein the extruder head comprises one or more second heating elements arranged to transfer heat into the extrusion material from a second side of the profile height opposite to the first side, wherein the control unit is operatively connected to the one or more first heating elements and the one or more second heating elements for generating an adjustable height temperature gradient in the extrusion material over the profile height for controlling the expansion of the extrusion material after the extrusion material leaves the die.

3. Extruder according to claim 2, wherein the one or more second heating elements comprise a plurality of second heating elements distributed over the profile width, wherein the control unit is arranged to individually control the temperature of each of the plurality of second heating elements over the profile width.

4. Extruder according to claim 3, wherein each one of the plurality of first heating elements is arranged opposite one of the plurality of second heating elements in the direction of the profile height, wherein the control unit is arranged for generating a height temperature gradient between each set of two opposite heating elements.

5. Extruder according to claim 3, wherein the control unit is arranged to generate an adjustable width temperature gradient over the profile width in addition to the adjustable height temperature gradient in the profile height.

6. Extruder according to claim 5, wherein the extruder head is provided with a flow channel arranged in fluid communication with a supply of extrusion material from a lateral end of the extruder head for receiving the extrusion material into the die parallel to the profile width, wherein the control unit is arranged for controlling the width temperature gradient such that it increases towards the distal end of the profile width relative to the supply of extrusion material.

7. Extruder according to claim 5, wherein the control unit is arranged to control the minimum temperature of the plurality of first heating elements and the plurality of second heating elements to at least eighty degrees Celsius or at least ninety degrees Celsius.

8. Extruder according to claim 1, wherein the one or more first heating elements are located at the die for transferring heat into the extruded material from a first side of the profile height at the die.

9. Extruder according to claim 1, wherein the extruder is provided with a flow channel into the die, wherein the one or more first heating elements are located at the die downstream of the flow channel for transferring heat into the extruded material from a first side of the profile height at the die.

10. Extruder according to claim 2, wherein the one or more second heating elements are located at the die for transferring heat into the extruded material from a second side of the profile height at the die.

11. Extruder according to claim 2, wherein the extruder is provided with a flow channel into the die, wherein the one or more second heating elements are located at the die downstream of the flow channel for transferring heat into the extruded material from a second side of the profile height at the die.

12. A method of extruding a cord-reinforced tire component using an extruder comprising an extruder head, wherein the extruder head comprises a die for receiving an extruded material and a cord guide for guiding the cord into the die, wherein the die is provided with an elongated cross-sectional profile defining a first cross-section of the extruded material in the die, wherein the cross-sectional profile has a profile width and a profile height which is small in relation to the profile width, wherein the extruder head is provided with one or more first heating elements, wherein the extruder further comprises a control unit which is operatively connected to the one or more first heating elements, wherein the method comprises the steps of: receiving an extruded material in a die; guiding the cord from the cord guide into the die at a cord entry height relative to the profile height such that the cord is embedded in the extruded material; controlling the one or more first heating elements with the control unit to transfer heat into the extruded material from a first side of the profile height for generating an adjustable height temperature gradient in the extruded material over the profile height; and controlling expansion of the extruded material relative to the cord entry height from the first cross section to the second cross section after the extruded material exits the die by adjusting the adjustable height temperature gradient, wherein the one or more first heating elements comprise a plurality of first heating elements distributed over the profile width, wherein the method comprises the steps of: controlling a temperature of each of the plurality of first heating elements individually across a profile width.

13. The method of claim 12, wherein the extruder head comprises one or more second heating elements, wherein the control unit is operatively connected to the one or more first heating elements and the one or more second heating elements, wherein the method comprises the steps of: controlling the one or more first heating elements and the one or more second heating elements with a control unit to transfer heat into the extruded material from a first side and a second side, respectively, of the profile height for creating an adjustable height temperature gradient in the extruded material over the profile height; and controlling expansion of the extruded material relative to the cord entry height from the first cross section to the second cross section after the extruded material exits the die by adjusting the adjustable height temperature gradient.

14. The method of claim 13, wherein the one or more second heating elements comprise a plurality of second heating elements distributed across a width of the profile, wherein the method comprises the steps of: controlling the temperature of each of the plurality of second heating elements individually across the profile width.

15. The method of claim 14, wherein each of the plurality of first heating elements is disposed opposite one of the plurality of second heating elements in a direction of a profile height, wherein the method comprises: a height temperature gradient between each set of two opposing heating elements is created.

Technical Field

The present invention relates to an extruder and a method for extruding cord reinforced tire components.

Background

The known extruder comprises an extruder head for extruding a cord-reinforced tire component, comprising a die defining a cross-sectional profile, through which the extruded material is pushed, and a cord guide for guiding the reinforcement cord into the die. Once the reinforcing cords leave the cord guide and enter the die, they are embedded in the extrusion material and are no longer guided by the cord guide. Since the extruded material is substantially uniform, the reinforcing cords are embedded in a constant position with respect to the cross-section of the tire component. The precise positioning of the reinforcing cords relative to the cross-section of the tire component is critical to achieving the desired characteristics of the tire component. Typically, the reinforcing cords are pre-positioned in the cord guide within a tolerance of 5/100 millimeters with respect to the cross-section of the mold.

It may be desirable to vary the relative positioning of the reinforcing cords with respect to the cross-section of the tire component to meet the particular requirements of a particular batch of tire components. Currently, this requires replacing the extruder head with another extruder head having a different cord guide. Since the extruder head is a very expensive die piece, it is very expensive to have a specific extruder head for each reinforcement cord positioning. Furthermore, interchanging the extruder head requires time and results in undesirable downtime of the extruder head.

It is an object of the present invention to provide an extruder and a method for extruding cord-reinforced tire components, wherein the flexibility of positioning of the cords within the tire component can be improved.

Disclosure of Invention

According to a first aspect, the present invention provides an extruder with an extruder head for extruding a cord-reinforced tire component, wherein the extruder head comprises a die for receiving an extruded material and a cord guide for guiding the cord into the die such that, in use, the cord is embedded in the extruded material, wherein the die is provided with a cross-sectional profile defining a first cross-section of the extruded material in the die, wherein the cross-sectional profile has a profile height, wherein the cord guide is arranged for guiding the cord into the die at a cord entry height with respect to the profile height, wherein the extruder head is provided with one or more first heating elements arranged to transfer heat from a first side of the profile height into the extruded material, wherein the extruder further comprises a control unit operatively connected to the one or more first heating elements, for creating an adjustable height temperature gradient in the extruded material over the profile height to control the expansion of the extruded material from the first cross section to the second cross section relative to the cord entry height after the extruded material exits the die.

The adjustable height temperature gradient may cause the first viscosity and associated first flow rate of the extrusion material in the bottom section to be unequal to the second viscosity and associated second flow rate of the extrusion material in the top section. By controlling the non-uniform viscosity and flow over the profile height, the expansion of the extruded material from the first cross-section to the second cross-section can be effectively controlled after the extruded material exits the die. The lower viscosity allows the extruded material to flow more easily through the die at a higher flow rate while the rate at which the cord is fed through the die remains constant. When the flow is higher than the cord speed, the extruded material will expand to a greater height after exiting the die relative to the cord entry height. Thus, the final cord height can be controlled in proportion to the height of the extrudate. The final cord height relative to the height of the extrudate can be controlled to vary proportionally to the cord entry height relative to the profile height. Thus, when a different cord position relative to the cross-section of the extruded material is desired, the extruder head no longer needs to be changed. The control unit may simply be used in combination with one or more first heating elements to adjust the range of height temperature gradients to control the relative position of the cords with respect to the second cross section of the extruded material.

JPH06231633A discloses a known peripheral extrusion coating apparatus with a cross head for coating rubber-plastic lined cables. The circumferential flow channel of the cross head is divided into a plurality of zones, each zone having its own thermostat. The temperature regulating device is controlled based on the measurement value of the downstream flow temperature sensor. The aim of this known extrusion coating device is to provide a uniform coverage of the coating in the circumferential direction of the cable. In JPH06231633A, it is taught that the temperature distribution should be uniform and homogeneous. JPH06231633A explicitly discloses that any temperature gradient disappears and thickness deviations in radial, circumferential and longitudinal directions are prevented. JPH06231633A does not disclose an extruder head for extruding cord reinforced tire components. Furthermore, JPH06231633A does not suggest nor suggest that the control unit is arranged to deliberately create and control an adjustable height temperature gradient in the extruded material over the profile height.

In one embodiment, the one or more first heating elements are located at the die for transferring heat into the extruded material from a first side of the profile height at the die. Preferably, the extruder is provided with a flow channel into the die, wherein the one or more first heating elements are located at the die downstream of the flow channel for transferring heat into the extruded material from a first side of the profile height at the die. The location of the one or more first heating elements at the die allows for better and/or direct control of the final cord height relative to the cord entry height by creating a height temperature gradient at the die. It should be noted that in the known cross-head of JPH06231633A, the temperature regulating device is located upstream of the die in the flow channel and is therefore not provided for accurately controlling the final cord height (if any) at the die.

In a preferred embodiment, the height temperature gradient over the profile height is at least five degrees celsius, preferably at least ten degrees celsius. Such a high temperature gradient may produce a significant difference in the amount of expansion of the extruded material between the bottom section and the top section.

In one embodiment, the one or more first heating elements comprise a plurality of first heating elements distributed across the width of the profile. The plurality of first heating elements may more evenly transfer heat from the first side into the extrusion material.

In a multifunctional embodiment thereof, the control unit is arranged to control the temperature of each of the plurality of first heating elements individually over the profile width. Thus, the heat transfer from the first side into the extruded material over the profile width can be precisely controlled.

In one embodiment, the control unit is arranged for generating a height temperature gradient in the extruded material over the entire profile width or substantially the entire profile width. The expansion of the extruded material from the first cross section to the second cross section can thus be controlled over the entire profile width. Preferably, the control unit is arranged for generating the height temperature gradient in the extruded material uniformly over the entire profile width or substantially the entire profile width. The extruded material can thus be controlled to expand uniformly over the entire profile width in the direction of the profile height.

In a more refined embodiment, the extruder head comprises one or more second heating elements arranged to transfer heat into the extruded material from a second side of the profile height opposite the first side, wherein the control unit is operatively connected to the one or more first heating elements and the one or more second heating elements for generating an adjustable height temperature gradient in the extruded material over the profile height for controlling the expansion of the extruded material after it leaves the die. The control unit may simply be used in combination with the one or more first heating elements and the one or more second heating elements to adjust the extent of the height temperature gradient and/or the direction of increase of the height temperature gradient to control the amount and/or direction of expansion of the extruded material.

In one embodiment, the one or more second heating elements are located at the die for transferring heat into the extruded material from a second side of the profile height at the die. Preferably, the extruder is provided with a flow channel into the die, wherein the one or more second heating elements are located at the die downstream of the flow channel for transferring heat into the extruded material from a second side of the profile height at the die. The position of the one or more first heating elements and the one or more second heating elements at the die allows for better and/or direct control of the final cord height relative to the cord entry height by creating a height temperature gradient at the die. It is again noted that in the known cross-head of JPH06231633A, the temperature regulating device is located upstream of the die in the flow channel and is therefore not provided for accurately controlling the final cord height (if any) at the die.

In an embodiment, the control unit is arranged for switching between a first mode in which the height temperature gradient is controlled to increase the temperature from the first side towards the second side and a second mode in which the height temperature gradient is controlled to increase the temperature from the second side towards the first side. Thus, the direction of expansion may be directed to the section at the side with the lowest viscosity, the first side in the first mode and the second side in the second mode.

In one embodiment, the one or more second heating elements comprise a plurality of second heating elements distributed over the width of the profile. The plurality of second heating elements may more evenly transfer heat from the second side into the extruded material.

In one embodiment, the control unit is arranged to control the temperature of each of the plurality of second heating elements individually over the profile width. Thus, the heat transfer into the extruded material from the second side over the profile width can be precisely controlled.

In an embodiment, each of the plurality of first heating elements is arranged opposite one of the plurality of second heating elements in the direction of the profile height, wherein the control unit is arranged for generating a height temperature gradient between each set of two opposite heating elements. Thus, for each location on the profile width, a height temperature gradient may be generated by the heating element on the opposite side of the profile height at that location.

In one embodiment, the control unit is arranged to generate an adjustable width temperature gradient over the profile width in addition to the adjustable height temperature gradient in the profile height. The width temperature gradient is particularly useful for ensuring that the extruded material reaches the distal end of the profile width.

Preferably, the extruder head is provided with a flow channel arranged in fluid communication from a lateral end of the extruder head with a supply of extrusion material for receiving the extrusion material into the die parallel to the profile width, wherein the control unit is arranged for controlling the width temperature gradient such that it increases towards the distal end of the profile width relative to the supply of extrusion material. Extruders with a lateral supply of extrusion material are known as "cross dies". The direction of increase of the width temperature gradient may be used to ensure that the extrusion material reaches the distal end of the cross-sectional profile relative to the source of extrusion material.

In an embodiment, the control unit is arranged to control the minimum temperature of the plurality of first heating elements and the plurality of second heating elements to at least eighty degrees celsius, preferably at least ninety degrees celsius. The minimum temperature may correspond to the maximum viscosity allowed for proper extrusion of the extruded material.

In an embodiment, the cross-sectional profile comprises at least one tapered region, wherein the control unit is arranged to locally increase the temperature in said at least one tapered region. The local increase in temperature may allow the extruded material to more easily flow into a tapered region or other narrow region of the cross-sectional profile.

In one embodiment, the extrusion in use cures into an extrudate with the cords at a final cord height within the extrudate, wherein the extruder includes a sensor for detecting the final cord height of the cords in the extrudate. The sensor may be used to verify the positioning of the cord within the extrudate.

Preferably, the sensor is an inductive sensor. The inductive sensor can electronically sense the proximity of the cord to the sensor without damaging the extrudate.

Preferably, the control unit is arranged to generate the height temperature gradient based on measurements from the sensor. Feedback from the sensor to the control unit may improve the accuracy of the cord positioning and may even allow for online adjustment of the expansion.

In one embodiment, the heat is arranged to be transferred conductively. Thus, heat may be transferred indirectly, for example, through the material of the extruder head into the extruded material.

In another embodiment, the profile width extends in a horizontal direction or a substantially horizontal direction, and/or wherein the profile height extends in a vertical direction or a substantially vertical direction.

In one embodiment, the cross-sectional profile is elongated in the direction of the profile width relative to the smaller profile height.

In one embodiment, the mold has a cross-sectional profile arranged to extrude a sheet and/or film, in particular a tire tread.

According to a second aspect, the present invention provides a method of extruding a cord-reinforced tire component using the aforementioned extruder comprising an extruder head, wherein the extruder head comprises a die for receiving an extruded material and a cord guide for guiding the cord into the die, wherein the die is provided with a cross-sectional profile defining a first cross-section of the extruded material in the die, wherein the cross-sectional profile has a profile height, wherein the extruder head is provided with one or more first heating elements, wherein the extruder further comprises a control unit operatively connected to the one or more first heating elements, wherein the method comprises the steps of: receiving an extruded material in a die; guiding the cord from the cord guide into the die at a cord entry height relative to the profile height such that the cord is embedded in the extruded material; controlling the one or more first heating elements with the control unit to transfer heat into the extruded material from a first side of the profile height for generating an adjustable height temperature gradient in the extruded material over the profile height; and controlling expansion of the extruded material from the first cross-section to the second cross-section relative to the cord entry height by adjusting the adjustable height temperature gradient after the extruded material exits the die.

In a preferred embodiment of the method, the height temperature gradient over the height of the profile is at least five degrees celsius, preferably at least ten degrees celsius.

In one embodiment, the one or more first heating elements comprise a plurality of first heating elements distributed over the width of the profile, wherein the method comprises the steps of: controlling a temperature of each of the plurality of first heating elements individually across a profile width.

In one embodiment, the height temperature gradient in the extruded material is generated over the entire profile width or substantially the entire profile width. Preferably, the height temperature gradient in the extruded material is generated uniformly over the entire profile width or substantially the entire profile width.

In a more detailed embodiment, the extruder head comprises one or more second heating elements, wherein the control unit is operatively connected to the one or more first heating elements and the one or more second heating elements, wherein the method comprises the steps of: controlling the one or more first heating elements and the one or more second heating elements with a control unit to transfer heat into the extruded material from a first side and a second side, respectively, of the profile height for creating an adjustable height temperature gradient in the extruded material over the profile height; and controlling expansion of the extruded material from the first cross-section to the second cross-section relative to the cord entry height by adjusting the adjustable height temperature gradient after the extruded material exits the die.

In one embodiment, the method comprises: the control unit is switched between a first mode in which the height temperature gradient is controlled to increase the temperature from the first side toward the second side, and a second mode in which the height temperature gradient is controlled to increase the temperature from the second side toward the first side.

In one embodiment, the one or more second heating elements comprise a plurality of second heating elements distributed over the width of the profile, wherein the method comprises the steps of: controlling the temperature of each of the plurality of second heating elements individually across the profile width.

In one embodiment, each of the plurality of first heating elements is arranged opposite to one of the plurality of second heating elements in a direction of a profile height, wherein the method comprises: a height temperature gradient between each set of two opposing heating elements is created.

In one embodiment, the method comprises: in addition to the adjustable height temperature gradient in the profile height, an adjustable width temperature gradient over the profile width is also generated.

In one embodiment, the method comprises the steps of: controlling a minimum temperature of the first plurality of heating elements and the second plurality of heating elements to at least eighty degrees Celsius, preferably at least ninety degrees Celsius.

In one embodiment, the cross-sectional profile comprises at least one tapered region, wherein the method comprises the steps of: locally increasing the temperature in the at least one tapered region.

In one embodiment, the extruded material is cured into an extrudate, wherein the cords are at a final cord height within the height of the extrudate, wherein the extruder comprises a sensor for detecting the final cord height of the cords in the extrudate, wherein the method comprises the steps of: the height temperature gradient is controlled based on measurements from the sensor.

The method provides the steps of using the extruder described above and therefore has the same advantages over the prior art as previously described with respect to the corresponding features of the extruder.

In a particular embodiment of the method, the tire component is a tire component of the group comprising a cushion ply, a body ply, a cover tape, a chafer or any other tire component having cords.

The various aspects and features described and shown in the description can be applied separately whenever possible. These individual aspects, in particular aspects and features described in the appended dependent claims, may be subject matter of divisional applications.

Drawings

The invention will be described below with reference to exemplary embodiments shown in the accompanying schematic drawings, in which:

FIG. 1A shows a front view of an extruder with an extruder head including a cord guide and a die according to the present invention;

FIG. 1B shows a cross-section of the extruder head taken according to line IB-IB in FIG. 1A;

FIGS. 2A and 2B show the extruder according to FIGS. 1A and 1B, respectively, with the relative position of the reinforcing cords raised; and

fig. 3A and 3B show the extruder according to fig. 1A and 1B, respectively, with the relative position of the reinforcing cords lowered.

Detailed Description

Fig. 1A and 1B show an extruder 1 according to the invention for extruding an extrudate 90 in the form of a cord-reinforced tire component. The cord reinforced tire component is formed by embedding cords 8 (preferably steel or textile reinforcing cords) in an extrusion material 9 (preferably an elastomer or rubber compound) during the extrusion process.

The extruder 1 comprises an extrusion material source 2 for supplying an extrusion material 9 in a feed direction S and an extruder head 3 for receiving the extrusion material 9 from the extrusion material source 2 in the feed direction S. The extruder head 3 comprises a die 4 for guiding the extrusion material 9 from the feeding direction S to the extrusion direction E while forming the extrusion material 9 into an extrudate 90 of a desired shape defined by the die 4. The feeding direction S is perpendicular to the extrusion direction E, so that the extrusion material 9 is supplied laterally or from a lateral end of the extruder 1 into the die 4. The die 4 arranged to receive the extruded material 9 laterally is called a "cross die". The extruder 1 is provided with a cord guide 5 for guiding a cord 8 in a guide plane P into the die 4 in an extrusion direction E such that, in use, the cord 8 is embedded in the extrusion material 9. The extruder 1 further comprises a control unit 6 for controlling extrusion parameters and optionally a sensor 7.

The extruder head 3 comprises a first extruder half 31 and a second extruder half 32, which first extruder half 31 and second extruder half 32, when mounted together as shown in fig. 1A and 1B, enclose the die 4 and the cord guide 5 with a guide plane P between the die 4 and the cord winder 5. The extruder halves 31, 32 can be disassembled in a manner known per se for inserting the cord 8 between the extruder halves 31, 32 at the cord guide 5. In this example, the first extruder half 31 is located at the bottom of the extruder head 3 and the second extruder half 32 is located at the top of the extruder head 3 or on top of the first extruder half 31. The extruder head 3 comprises a first flow channel 33 in the first extruder half 31 and a second flow channel 34 in the second extruder half 32. The flow channels 33, 34 are in fluid communication with the source of extrusion material 2 at the lateral ends of the extruder head 3 in the feeding direction S to direct separate flows of extrusion material 9 into the die 4, as schematically shown by arrows F1 and F2. The flow channels 33, 34 extend laterally through the extruder head 3 for laterally distributing the extruded material 9 before being poured or merged into the die 4 from opposite sides of the guide plane P.

The die 4 is provided with an opening 41, the opening 41 having a cross-sectional profile 42 defining the shape of the extruded material 9 in the die 4. The cross-sectional profile 42 has a profile width W and a profile height H1. In this example, the profile width W extends in a horizontal or substantially horizontal direction, and the profile height H1 extends in a vertical or substantially vertical direction. The cross-sectional profile 42 is elongate in the direction of the profile width W and has a relatively small profile height H1 relative to the profile width W. Thus, the die 4 is arranged for extruding sheets and/or films. The cross-sectional profile 42 divides the extruder head 3 into a first side a below the profile height H1 and a second side B above the profile height H1, corresponding in this example to the first extruder half 31 and the second extruder half 32, respectively. In the die 4, the extruded material 9 has a first cross section C1. As shown in fig. 2A and 2B and fig. 3A and 3B, the shape of the extruded material 9 may be controlled to expand or swell from a first cross section C1 inside the die 4 to a second cross section C2 or a third cross section C3 outside the die 4 having a larger surface area than the first cross section C1. The heights of the expanded second and third cross-sections C2 and C3 are denoted by H2 and H3, respectively. The expansion occurs when the extrusion material 9 is fed into the die 4 at a flow rate exceeding the rate at which the cord 8 is fed into the die 4 in the extrusion direction E.

In the exemplary embodiment, cross-sectional profile 42 has a trapezoidal shape including a linear or linear bottom edge 43, a linear or linear top edge 44 extending parallel to bottom edge 43, and a first tapered or triangular region 45 and a second tapered or triangular region 46 connecting bottom edge 43 to top edge 44 at opposite ends of profile width W. The shape of the exemplary cross-sectional profile 42 is similar to and arranged for extruding the extrusion material 9 into the shape of the tire tread. However, it will be apparent to those skilled in the art that the scope of the present invention includes a variety of cross-sectional profiles.

The extruder head 3 is provided with one or more first heating elements (in this example a plurality of first heating elements 35) and one or more second heating elements (in this example a plurality of second heating elements 36). A first heating element 35 extends in the first extruder half 31 and is arranged in direct contact with the material (typically metal) of the first extruder half 31 for transferring heat into the material of the first extruder half 31 and finally into the extruded material 9 in direct contact with the first extruder half 31 at the first flow channel 33 and the die 4. In particular, the one or more first heating elements are located downstream of the first flow channel 33 at or along the mould 4 for transferring heat into the material at the mould 4. As shown in fig. 1B, the first heating element 35 extends in a portion of the extruder head 3 vertically below the die 4. A second heating element 36 extends in the second extruder half 32 and is arranged in direct contact with the material (typically metal) of the second extruder half 32 for transferring heat into the material of the second extruder half 32, eventually into the extruded material 9 in direct contact with the second extruder half 32 at the second flow channel 34 and the die 4. In particular, the one or more second heating elements are located downstream of the second flow channel 34 at the die 4 or along the die 4 for transferring heat into the material at the die 4. As shown in fig. 1B, the second heating element 36 extends in a portion of the extruder head 3 vertically above the die 4. Preferably, heat is transferred conductively. However, other heat transfer means, such as heat radiation, may also be applied. In this example, the first and second heating elements 35, 36 are formed as integral channels within the respective extruder half 31, 32 for receiving a heating medium in direct contact with the respective extruder half 31, 32. Alternatively, the first heating element 35 and the second heating element 36 may be formed as electric heaters.

The first heating element 35 and the second heating element 36 are distributed parallel to or across the profile width W of the cross-sectional profile 42. Preferably, the first heating element 35 and the second heating element 36 are evenly distributed over the profile width W, so that heat can be evenly transferred into the extruder halves 31, 32 and finally into the extruded material 9. Most preferably, for each first heating element 35, there is a second heating element 36 opposite thereto in the direction of the profile height H1. As shown in fig. 1A, the first heating element 35 in the first extruder half 31 is arranged at a constant distance from the bottom edge 43 of the cross-sectional profile 42 in the direction of the profile height H1, while the second heating element 36 in the second extruder half 32 is arranged at a constant distance from the top edge 44 and the tapered regions 45, 46 in the direction of the profile height H1. Thus, at least the second heating element 36 located at the second side B above the tapered regions 45, 46 is closer to the guiding plane P and the first heating element 35 is opposite the profile height H1.

The heat generated by each of the first and second heating elements 35, 36 may be regulated in a manner described in more detail below.

As shown in fig. 1B, a cord guide 5 is formed at the fitting between the extruder halves 31, 32. The cord guide 5 comprises a plurality of known mutually parallel guide channels (not shown) formed in one or both of the extruder halves 31, 32 and arranged for guiding each cord 8 in a guide plane P towards the die 4. The guide plane P extends between the extruder halves 31, 32 at a cord entry height H4 relative to the bottom or bottom edge 43 of the cross-sectional profile 42. The cord guide 5 extends up to the mould 4 but not into the mould 4. The cord 8 is introduced into the die 4 from the cord guide 5 at a cord entry height H4 and is immediately embedded into the extrusion material 9 flowing into the die 4 from the flow channels 33, 34 from both sides A, B of the profile height H1 at said cord entry height H4. For the purposes of the present invention, the cord entry height H4 is expressed as a relative or proportional value, particularly as a percentage of the profile height H1. In this example, the cord entry height H4 is approximately 50% of the profile height H1. The cord entry height H4 and/or the guide plane P divides the cross-sectional profile 42 into a lower section below the cord entry height H4 and an upper section above the cord entry height H4. Each segment receives a volume of extruded material 9 that together embed the cords 8 from opposite sides A, B of the guide plane P.

As shown in fig. 1A, the control unit 6 is operatively connected to each first heating element 35 and each second heating element 36 for individually controlling the heat or the temperature of the heat of each of the above-mentioned heating elements 35, 36. The control unit 6 is in particular arranged to control the first heating element 35 and/or the second heating element 36 to produce an adjustable height temperature difference, Δ or gradient G1, G2, in the extruded material 9 over the profile height H1, as schematically shown in the temperature diagrams in fig. 2A and 2B and fig. 3A and 3B. The height temperature gradients G1, G2 result in a non-uniform viscosity in the extruded material 9 over the profile height H1. More specifically, the height temperature gradients G1, G2 cause the viscosity of the extruded material 9 of one of the lower and upper sections to be unequal to the viscosity of the extruded material 9 of the other of the lower and upper sections.

A method of extruding a cord-reinforced tire component using the above-described extruder 1 will be described with reference to a normal state shown in fig. 1A and 1B, a first mode shown in fig. 2A and 2B, and a second mode shown in fig. 3A and 3B.

In the normal state of fig. 1A and 1B, the control unit 6 is arranged to set each first heating element 35 and the respective second heating element 36 opposite the first heating element 35 to the same or substantially the same temperature in the direction of the profile height H1, so that the temperature of the extruded material 9 is substantially constant over the profile height H1. This also applies to the state in which the first heating element 35 and the second heating element 36 are inactive. The cord 8 entering the die 4 from the cord guide 5 at the cord entry height H4 will be embedded in the extrusion material 9 flowing into the die 4 from both sides A, B of the guide plane P. Under normal conditions, the viscosity of the extruded material 9 is substantially constant over the profile height H1. As a result, the flows F1, F2 of extruded material 9 in the lower and upper sections have equal viscosities and therefore flow at the same speed and volume flow rate in the extrusion direction E. Thus, the extruded material 9 does not expand or uniformly expand toward both sides A, B after exiting the die 4. As a result, the cord 8 will remain substantially at the cord entry height H4, which in this example is about 50% of the profile height H1.

In the first and second modes, as shown in fig. 2A and 2B and fig. 3A and 3B, respectively, the control unit 6 is arranged to control the height temperature gradients G1, G2 to ultimately affect and/or change the expansion of the extruded material 9 after the extruded material 9 leaves the die 4 to the extent that the relative position of the expanded second cross section C2 of the extrudate 90 with respect to the cord entry height H4 is reduced. To achieve this, the control unit 6 is arranged to generate an adjustable height temperature gradient G1, G2 that increases from the second side B towards the first side a of the profile height H1. In particular, the control unit 6 is arranged for activating only the first heating elements 35, or alternatively for setting the first heating elements 35 to a higher temperature than the temperature of the respective second heating elements 36. In each case, a disproportionate amount of heat is transferred into the extrusion material 9 from the first side a of the profile height H1 to increase the viscosity of the extrusion material 9 in the lower section relative to the extrusion material 9 in the upper section.

The temperature height gradients G1, G2 produce a non-uniform viscosity in the extruded material 9 over the profile height H1. The flow F1 of the extruded material 9 flowing at the lower section has a lower viscosity than the other flow F2, resulting in a higher flow rate than the other flow F1 in the upper section. In particular, the speed of the flow of the extruded material 9 through the lower section in the extrusion direction E is higher than the speed of feeding the cord 8 in the same extrusion direction E. This results in the remaining volume of extruded material 9 leaving the die 4 from the lower section at a higher pressure and expanding in the direction of the first side a. The shape of the extruded material 9 expands or expands from a first cross section C1 in the die 4 towards a second cross section C2 outside the die 4 and then solidifies to form the extrudate 90.

As a result, the height H2 of the cord 8 extending at the cord entry height H4 relative to the extrudate 90 is at a final cord height H5 that is relatively or proportionally higher than the cord entry height H4 relative to the profile height H1. Specifically, in this embodiment, the final cord height H5 is about 60% of the height H2 of the extrudate 90 relative to the bottom (side a) of the extrudate 90. In other words, the thickness of the extruded material 9 of the extrudate 90 at the first side a is increased relative to the thickness of the same extruded material 9 when contained in the die 4.

In a second mode, as shown in fig. 3A and 3B, the control unit 6 is arranged to generate an adjustable height temperature gradient G1, G2 that increases from the first side a towards the second side B of the profile height H1. In particular, the control unit 6 is arranged for activating only the second heating element 36, or is arranged to set the second heating element 36 to a higher temperature than the temperature of the respective first heating element 35. In each case, a disproportionate amount of heat is transferred into the extruded material 9 from the second side B of the profile height H1 to increase the viscosity of the extruded material 9 in the upper section relative to the extruded material 9 of the lower section.

As a result, the third cross section C3 expands in the direction of the second side B relative to the first cross section C1. As the height H3 of the second cross section C3 increases, the height H3 of the cord 8 relative to the second cross section C3 is located at a final cord height H6 which is opposite or proportionally lower than the entry cord height H4 relative to the profile height H1. In this example, the final cord height H6 is only 40% of the height H3 of the second cross-section C3. In other words, the thickness of the extruded material 9 above the final cord height H6 is substantially thicker than the thickness of the extruded material 9 above the cord entry height H4 while the extruded material 9 is still contained in the die 4.

In each of the above-described modes, the control unit 6 is arranged for generating a local temperature increase (not shown) or an additional adjustable width temperature difference Δ or gradient G3, G4 in the extruded material 9 over the profile width W, thus generating an additional adjustable non-uniform viscosity. The width temperature gradients G3, G4 are schematically illustrated in temperature graphs in fig. 2A and 2B and fig. 3A and 3B. Preferably, the control unit 6 is arranged to control the first heating element 35 and the second heating element 36 such that the width temperature gradients G3, G4 increase relative to the extrusion material source 2 from the extrusion material source 2 towards the distal end of the cross-sectional profile 42. As a result, in the first mode, the temperature of the second heating element 36 is increased due to the width temperature gradient G3 from the first temperature T1 to the second temperature T2 of the profile width W, whereas in the first mode, the temperature of the first heating element 35 is increased due to the width temperature gradient G4 from the third temperature T3 to the fourth temperature T4. Similarly, in the second mode, the temperature of the first heating element 35 increases due to the width temperature gradient G3 from the first temperature T1 to the second temperature T2 of the profile width W, while in the second mode, the temperature of the second heating element 36 increases due to the width temperature gradient G4 from the third temperature T3 to the fourth temperature T4.

The width temperature gradients G3, G4 may be particularly useful to ensure that the extruded material 9 reaches the distal end of the cross-sectional profile 42 relative to the source of extruded material 2. A local increase in temperature (not shown) may cause the extruded material 9 to flow more easily into the tapered regions 45, 46 or other narrow regions of the cross-sectional profile 42.

According to this mode, the control unit 6 is arranged to bring the heating elements 35, 36 on one side A, B of the contour height H1 to the first temperature T1 or, in the case of the above-mentioned width temperature gradient G3, G4, to a temperature range between the first temperature T1 and the second temperature T2, while setting the heating elements 35, 36 at the other side A, B to the third temperature T3 or, in the case of the above-mentioned width temperature gradient G3, G4, to a temperature range between the third temperature T3 and the fourth temperature T4. Each heating element 35, 36 at one side A, B is set to a higher temperature than the temperature of the respective heating element 35, 36 at the other side A, B opposite or vertically opposite the heating element 35, 36 along the direction of the profile height H1. The temperature difference between each first heating element 35 and its corresponding second heating element 36 is preferably at least five degrees celsius, more preferably at least ten degrees celsius. Similarly, the height temperature gradient G1, G2 in the extruded material 9 ranges preferably at least five degrees celsius, more preferably at least ten degrees celsius over the profile height H1.

The control unit 6 is arranged for generating an adjustable height temperature gradient G1, G2 over the entire profile width W to ensure that the expansion of the first cross section C1 to the second cross section C2 is controlled uniformly with respect to the cord entry height H4. In particular, in case of a height temperature gradient G1, G2, the control unit 6 is arranged for controlling the first heating element 35 and the second heating element 36 as a first group and a second group offset with respect to the first group. The control unit 6 is used to adjust the range or amount of the height temperature gradients G1, G2 and/or the width temperature gradients G3, G4. The control unit 6 is further arranged for switching between the first mode and the second mode, thereby changing the direction of the height temperature gradients G1, G2.

In the exemplary mode as shown in fig. 2A and 2B and fig. 3A and 3B, the first temperature T1 is eighty (80) degrees celsius, the second temperature T2 is one hundred (100) degrees celsius, the third temperature T3 is eighty-five (85) degrees celsius, and the fourth temperature T4 is one hundred twenty-five (125) degrees celsius. The temperatures T1-T4 are adjustable and can be variably controlled by the control unit 6, depending on the type of extruded material 9, the desired cord heights H2, H3 and/or the optimization of the distribution or expansion of the extruded material 9 over the profile width W. In the exemplary embodiment, first heating element 35 and second heating element 36 are used to heat extruded material 9 to a minimum temperature corresponding to a maximum viscosity that allows proper extrusion of extruded material 9. For an extruded material 9 in the form of a typical elastomeric compound for a tire component, the minimum temperature is at least eighty (80) degrees celsius, preferably at least ninety (90) degrees celsius. Thus, in the first mode, the first temperature T1 of the second heating element 36 is at least equal to the minimum temperature.

In the above mode, the control unit 6 is programmed according to given data on the rubber compounds and the corresponding viscosities at the respective temperatures T1-T4. The actual cord heights H2, H3 may be verified experimentally by cutting the extruded tire component to reveal the second cross section C2 or the third cross section C3 and the relative position of the cord 8 therein. The findings from experimental verification can then be used to improve the data and programming of the control unit 6.

Additionally or alternatively, as shown in fig. 1B, an optional sensor 7 may be provided at the exit of the die 4 where the extruded material 9 exits the extruder head 3 in the extrusion direction E. The sensor 7 is used to determine the actual cord height H2, H3 of the cord 8 in the extruded material 9. In this example, the sensor 7 is an inductive sensor that electronically senses the proximity of the metal cord 8 in the extruded material 8. The sensor 7 is operatively connected to the control unit 6 for sending a signal to the control unit 6 indicating the proximity of the cord 8 relative to the sensor 7. Thus, the control unit 6 may determine whether the actual cord heights H2, H3 correspond to the desired cord heights H2, H3 relative to the second or third cross-sections C2, C3 and, if necessary, adjust the temperatures of the first and second heating elements 35, 36 to improve the actual cord heights H2, H3 relative to the desired cord heights H2, H3. Such feedback between the sensor 7 and the control unit 6 can further improve the accuracy of the extruder 1 and even allow on-line adjustment of the expansion.

It should be understood that the above description is intended to illustrate the operation of the preferred embodiments and not to limit the scope of the invention. From the above discussion, many variations will be apparent to those skilled in the art and are encompassed by the scope of the present invention.