阅读说明：本技术 具有水平布置挤出筒的轮胎胎面制造挤出系统 (Tire tread manufacturing extrusion system with horizontally arranged extrusion barrels ) 是由 J·莫泰 J·D·威恩斯 于 2018-08-31 设计创作，主要内容包括：提供了挤出系统(10),其具有带第一和第二挤出筒(50,52)的第一和第二挤出机(12,14)。第一和第二挤出组分(24,26)通过筒(50,52)转移至模具(22),以从第一和第二挤出组分(24,26)共挤出轮胎胎面(20)。水平面(70)在垂直方向(40)上位于地面上方,并且延伸穿过第一挤出筒(50)和第二挤出筒(52)。(An extrusion system (10) is provided having first and second extruders (12,14) with first and second extruder barrels (50, 52). The first and second extruded components (24,26) are transferred through barrels (50,52) to a mold (22) to co-extrude the tire tread (20) from the first and second extruded components (24, 26). A horizontal plane (70) is located above the ground in the vertical direction (40) and extends through the first barrel (50) and the second barrel (52).)

1. An extrusion system for producing a tire tread, comprising:

a first extruder having a first barrel;

a first extruded component transferred through the first extrusion barrel;

a second extruder having a second barrel;

a second extrusion component transferred through a second extrusion barrel; and

a die receiving the first extrusion component and the second extrusion component to co-extrude the tire tread from the first extrusion component and the second extrusion component;

wherein a horizontal plane located above the ground in a vertical direction extends through the first and second barrels.

2. The extrusion system of claim 1, further comprising:

a third extruder having a third barrel;

a third extruded component transferred through a third extrusion barrel;

wherein the mold receives a third extruded component to co-extrude the tire tread from the first, second, and third extruded components;

wherein the horizontal plane extends through the first barrel, the second barrel, and the third barrel.

3. The extrusion system of claim 1 or 2, wherein the first extrusion barrel has a first extrusion screw that rotates about a first extrusion screw axis, and wherein the second extrusion barrel has a second extrusion screw that rotates about a second extrusion screw axis, and wherein the horizontal plane extends through the first extrusion screw axis and the second extrusion screw axis.

4. The extrusion system of any one of claims 1-3, wherein no portion of the first extruder is located within a foundation pit, and wherein no portion of the second extruder is located within the foundation pit.

5. The extrusion system of any one of claims 1-4, wherein the first extrusion component forms a first layer of the tire tread, and wherein the second extrusion component forms a second layer of the tire tread, wherein the first layer and the second layer have a width extending in the perpendicular direction;

and further comprising an adjustment mechanism that engages and rotates the tire tread such that the first layer is closer to the ground than the second layer.

6. The extrusion system of claim 1, wherein the first extrusion barrel has a first extrusion screw that rotates about a first extrusion screw axis, and wherein the second extrusion barrel has a second extrusion screw that rotates about a second extrusion screw axis, and wherein the horizontal plane extends through the first extrusion screw axis but not through the second extrusion screw axis.

7. The extrusion system of any one of claims 1-6, further comprising a conveyor that receives the tire tread.

8. The extrusion system of any one of claims 1-7, wherein the first extrusion component and the second extrusion component are different materials from one another.

9. The extrusion system of claim 8, wherein the first extrusion component is a synthetic rubber, a natural rubber, a combination of synthetic and natural rubber, a synthetic resin, or a combination of rubber and synthetic resin; and is

Wherein the second extrusion component is a synthetic rubber, a natural rubber, a combination of a synthetic rubber and a natural rubber, a synthetic resin, or a combination of a rubber and a synthetic resin.

10. The extrusion system of claim 1, wherein the first extruder has a first drive mechanism, and wherein the second extruder has a second drive mechanism, wherein the horizontal plane extends through the first drive mechanism, and wherein the horizontal plane extends through the second drive mechanism.

11. The extrusion system of any one of claims 1-10, wherein the die comprises a pre-former.

Technical Field

The present invention generally relates to extrusion systems for producing tire treads. More particularly, the present application relates to a tire tread extrusion system having horizontally arranged extrusion barrels that enable the co-extrusion of a tire tread and eliminate pockets in which one or more, but not all, of the extrusion barrels would otherwise be located.

Background

Extrusion is a manufacturing process in which an elastomeric material is formed into a final or intermediate shape. The shaped elastomeric material may be any type of material that is capable of being pressed from one shape and formed into another shape by pressure and, in some cases, heat. The elastomeric material may be synthetic or natural rubber, a combination of synthetic and natural rubber, synthetic resin or a combination of rubber and synthetic resin. A tire component is a product formed from an elastomeric material using an extrusion process.

One type of extrusion process utilizes a roller nose extruder. Here, the elastomeric material is first located within an extrusion barrel in which the helical screw is located. Rotation of the helical screw applies pressure to the elastomer and extrudes it from the extrusion barrel. The pushed elastomeric material may then be directed into a transition pressure chamber of the extrusion die. In the transition pressure chamber, the elastomeric material may be compressed or expanded, and the transition pressure chamber may be arranged differently. The elastomeric material may then be transferred between a mold and a roll, wherein the mold may be shaped and sized to provide the same desired shape and size of the elastomeric material. The elastomeric material is positioned against and pulled through the die by the rollers and, if desired, the rollers function to pull the elastomeric material downstream a distance to a subsequent processing stage.

Although it is possible to form a product of a desired shape and size, extrusion by using a roller nose extruder is limited because only a single type of material can be formed by a combination of a die and a roller after extrusion. To form products of different types of materials, a process known as co-extrusion may be employed. Coextrusion involves the use of two or more different extruders, each with its own helical screw, to force two or more different types of elastomeric materials into respective extrusion barrels. The two or more distinct material streams are moved into engagement with each other and exit the die as a single product made up of multiple extruded components.

The formation of the tire tread may be performed by a co-extrusion process, wherein a plurality of extruders, each having its own extrusion barrel, are arranged in a vertical plane with one another to direct its own extruded components into the head, resulting in the formation of tire treads having different rubber types at different locations. A known extrusion system 10 is shown in fig. 1, which includes three extruders 12,14, 16. The three barrels 50,52, 54 are arranged in a plane in which the vertical direction 40 lies. The extrusion barrels 50,52, 54 are arranged such that the extruded components 24,26, 28 are directed through the die 22 to form a coextruded tread 20 having three layers 34, 36, 38, each made of a different material.

Due to the vertical orientation of the extruders 12,14, 16, the tread 20 exits the mold 22 and is pulled by the rollers 30, thereby orienting the tread 20 with its road-engaging surface on top and its bottom layer on the bottom, as shown with reference to fig. 2. The tread 20 has a bottom first layer 34 made of the first extruded component 24, an intermediate second layer 36 made of the second extruded component 26, and a top third layer 38 made of the third extruded component 28. When the tread 20 leaves the die 22 in the vertical direction of the extruders 12,14, 16, it has that direction in the vertical direction 40 relative to the ground 18. The tread 20 may be transported downstream from the mold 22 by a roller 30 and then directed on a downstream second roller 32 to change its direction of travel while maintaining the tread 20 still facing the ground 18 and the vertical direction 40 such that the width of the tread 20 is not directed or extends toward the ground 18. The tread 20 may be moved downstream to a subsequent processing station for attachment to a carcass or processing into a retreaded belt.

Arranging the three barrels 50,52, 54 in a common vertical plane requires the presence of a foundation pit 42 arranged at a pit depth 44 of 2 to 3 meters from the floor 18 in the vertical direction 40. In the embodiment of fig. 1, at least a portion of the first barrel 50 and the first drive mechanism 56 are located within the foundation pit 42 at a distance downward from the ground surface 18 in the vertical direction 40. Extrusion system 10 may be provided with 2, 3, 4, 5 or more extruders, and any number of extruders, e.g., one or two, may have to be located within foundation pit 42. The entire barrel 50 or only a portion of the first barrel 50 may be located within the foundation pit 42. The placement of all or a portion of one, two, or more extruders within the foundation pit 42 allows for the performance of a co-extrusion process to produce the oriented multi-component tread 20 in question. Placement on a common vertical axis requires the construction of a large support structure 46 in the foundation pit 42 to support all of the extruders 12,14, 16. The construction of foundation pits 42 and support structures 46 may cost $ 750,000 and reduce the operator's ergonomics and maintenance accessibility. As such, there is still room for variation and improvement within the art of extrusion systems 10 for producing multi-component treads 20.

Drawings

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, which makes reference to the appended figures in which:

FIG. 1 is a side view of a prior art extrusion system for producing a tread made from multiple components.

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1, illustrating the tread and its orientation relative to the ground, with other elements of FIG. 1 removed.

FIG. 3 is a top view of an extrusion system for producing a tread made from multiple components.

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 3, illustrating the tread and its orientation relative to the ground, with the other elements of FIG. 3 removed.

FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 3, illustrating the tread and its orientation relative to the ground, with the other elements of FIG. 3 removed.

Fig. 6 is a left side view of the extrusion system of fig. 3.

Fig. 7 is a front view of the extrusion system of fig. 3.

Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention.

Detailed Description

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, and is not meant as a limitation of the invention. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a third embodiment. It is intended that the present invention encompass these and other modifications and variations.

It should be understood that the ranges mentioned herein include all ranges located within the specified range. Accordingly, all ranges mentioned herein include all sub-ranges contained within the mentioned range. For example, a range from 100 to 200 also includes ranges from 110 to 150, 170 to 190, and 153 to 162. Further, all limitations mentioned herein include all other limitations contained in the mentioned limitations. For example, a limit of at most 7 also includes a limit of at most 5, at most 3, and at most 4.5.

The present invention provides an extrusion system 10 that utilizes multiple extruders to produce a tire tread 20 made from multiple components. The extruder has an extruder barrel that is oriented in a horizontal plane 70 rather than a vertical plane with respect to the vertical direction 40. The extruder may be positioned in a vertical direction 40 relative to the floor 18 so that a foundation pit 42 is not required. The extruded tread 20 may exit the mold 22 in a rotational direction relative to the ground 18 and, if desired, may then be twisted by an adjustment mechanism 48 to orient the tread 20 at a desired angle relative to the ground 18.

Fig. 3 shows a top view of an extrusion system 10 having three extruders 12,14, 16 organized into a horizontal plane for extruding a tread 20 made of a plurality of extrusion components 24,26, 28. The coextrusion process shown may employ various types of extruders 12,14, 16, and it is to be understood that the types shown and described are merely exemplary. Further, although three extruders 12,14, 16 are shown, any number, such as 2, 4, 5, or up to 20 extruders, may be used in other embodiments. The first extruder 12 extrudes a first extruded component 24 and includes a first extrusion barrel 50, which may be an elongated cylinder having a helical screw contained therein. Second and third extruded components 26, 28 are also present in the disclosed extrusion system 10, but are different from each other and also from the first extruded component 24. The difference between the extruded components 24,26, 28 may be that they are not the same type of material as each other. In some cases, first extruded component 24 is a rubber having a particular composition, while second extruded component 26 is a rubber having a different composition, and third extruded component 28 is a rubber having a different additional composition. The extruded components 24,26, 28 are different materials from each other in that they include a unique material or materials, or they include the same material as another material, although in different proportions/combinations than the other extruded components 24,26 or 28.

A first extrusion screw, which may be the aforementioned helical screw, may be located within the first extrusion barrel 50. The first extrusion component 24 is introduced into the first extrusion barrel 50 through a first hopper 62 located on top of the first extrusion barrel 50 along the vertical direction 40. The first hopper 62 and the rear portion of the first extrusion barrel 50 may be referred to as a feeding portion of the first extruder 12. The first drive mechanism 56 is carried by the first extrusion barrel 50 and may be a motor, gear set, or any other motion generating or translating device that imparts rotational motion to the first extrusion screw within the first extrusion barrel 50. The rotation of the helical screw causes the first extruded component 24 to be broken up, compressed and formed into a more flexible form. The middle portion of the first barrel 50 may be referred to as the compression portion, and most of the forming and compression occurs in this portion. Rotation of the first extrusion screw may generate heat to further shape or destroy the first extruded component 24, and in addition, a heater may be positioned in the compression section to impart additional heat into the first extruded component 24 to aid in its shaping. . Continued rotation of the first extrusion screw pushes the first extruded component 24 down the entire length of the first extrusion barrel 50 to a metered portion at the end of the first extrusion barrel 50. From here, the pressure in the first extrusion barrel 50 will push the first extruded component 24 through an element such as a breaker plate, dome, die or mold. These elements will further shape or increase or decrease the size of first extruded component 24. The die 22 shown in fig. 3 is in communication with the first extrusion barrel 50 and directs the first extruded component 24 with the other extruded components 24,26 to the appropriate location and may vary in size or shape. It should be understood that the use of the term "mold" is broad enough to include the various described components, such as the dome, die, or breaker plate or any other element for directing and/or shaping the component 24, such as a pre-former. The die 22 may also function to divide the flow of the first extruded component 24 into two or more different flows for placement within the tread 20. The components 24,26, 28 are brought into engagement in the die 22 or are placed in close proximity to the die 22 and then brought into engagement with each other downstream of the die 22.

The extrusion system 10 may also include a second extruder 14 including a second extrusion barrel 52 containing a second extrusion component 26 introduced therein through a second hopper 64. As noted above, the second extruded component 26 is a different type of material than the first extruded component 24. The second extrusion screw in the second extrusion barrel 52 rotates to force the second extrusion component 26 out of the second extrusion barrel 52. The second drive mechanism 58 is used to rotate the helical screw contained within the second barrel 52. The second barrel 52 is isolated from the first barrel 50 so that their contents do not transfer to each other. In some embodiments, the first and second extrusion screws may be helical such that their rotation causes the first and second extruded components 24,26 to move out of and toward the die 22. In other arrangements, the use of first and second extrusion screws is not required, and any mechanism capable of rupturing and shaping and then extruding or removing first and second extruded components 24,26 from first and second extrusion barrels 50,52 may be employed. For example, meshing gears in the form of plunger devices, gravity feed devices, paddle wheel devices, or gear pumps may be used to push the first and second extruded components 24,26 through the extrusion system 10.

Also included is a third extruder 16 having a third extruder barrel 54 with a helical screw driven by a third drive mechanism 60. A third hopper 66 is present to allow insertion of third extrusion component 28 into third extrusion barrel 54. Third extrusion component 28 is shredded and formed in third extrusion barrel 54, and is subsequently pushed downstream to die 22. The second extruder 14 and the third extruder 16 may be constructed in the same manner as the elements described with respect to the first extruder 12 and this information need not be repeated. However, it may be the case that in other embodiments, the individual extruders 12,14, 16 are not constructed in the same manner and have different components and are arranged differently from one another so that they differ from one another.

Three extruded components 24,26 and 28 are pushed into the die 22 from their respective barrels 50,52, 54. The paths to the die 22 may all be the same, or one or more of the components 24,26, 28 may pass through an element such as a dome, while another one or more of the components 24,26, 28 do not. In some cases, there may be rollers on the downstream side of the die 22 on which the components 24,26, 28 exiting the die 22 are deposited. If present, the mold 22 may or may not engage such a roller. The die 22 functions to size and shape the extruded components 24,26, 28 and to engage them with each other or to bring them into close proximity so that they engage as they exit the die 22. In some embodiments, one or more streams of first extruded component 24, second extruded component 26, or third extruded component 28 do not pass through die 22, but rather have one or more of the other components 24,26, 28 disposed thereon as they will pass through die 22 for shaping and/or sizing.

The combined flow of the first, second, and third extruded components 24,26, 28, which make up the tread 20, exits the die 22 and is conveyed to the conveyor 68 and moves downstream for subsequent processing. Rollers, not shown in fig. 3, may be used to pull the tread 20 downstream to the conveyor 68. Alternatively, the movement of the conveyor 68 may serve to pull the tread 20 downstream and away from the mold 22. The tread 20 may be moved downstream from the conveyor 68 for subsequent processing. Subsequently, the tread 20 may be applied to a carcass to form a tire, or may be processed into a belt for a retreading process. The tread 20 exiting the mold 22 may be considered a finished product when engaging the conveyor 68 or otherwise being removed from the mold 22.

The three extruders 12,14, 16 are arranged such that they are oriented in a horizontal plane 70 rather than a vertical plane with respect to the vertical direction 40. As shown in the top view of fig. 3, the three barrels 50,52, 54 are all visible and are re-spaced from one another at the tread 20 and not located on top of one another. In certain embodiments, the barrels 50,52, 54 may be in contact with one another, but should be arranged such that they are located above the ground 18 and not placed in the foundation pit 42 such that some of the barrels 50,52, 54 are outside of the pit 42 and others are located completely or at least partially within the foundation pit 42. The horizontal placement of the barrels 50,52, 54 causes the extruded components 24,26, 28 to enter the die 22 at a ninety degree angle, which would otherwise cause the barrels 50,52, 54 to be vertically positioned relative to each other. The extruded components 24,26, 28 maintain their positions relative to each other as they flow through the die 22 and the relative positions as they exit such that the second extruded component 26 is between the first and third extruded components 24, 28 both before entering the die 22 and through the die 22 and exiting the die 22. However, in some embodiments, the channels in the die 22 may be shaped such that some of the extruded components 24,26, 28 change relative positions with respect to each other such that, for example, some or all of the first extruded component 24 is between all or some of the second and third extruded components 26, 28 as it exits the die 22.

From there, the tread 20 exiting the mold 22 is conveyed such that it is at an angle relative to the ground 18, since the side edges of the tread 20 are directly facing the ground 18, and the top and bottom of the tread 20 are not directly facing the ground 18. Fig. 4 shows the orientation of the tread 20 relative to the ground 18 at some point in the process in which the tread 20 has left the mold 22. The first extruded component 24 forms a first layer 34 of the tread 20 that is either a layer that is engaged with the carcass of the tire or a layer that is located at the bottom/radially inward position of the tire when the tread 20 is incorporated into the tire. The third extruded component 28 forms a third layer 38 of the tread 20, which is the initial ground-engaging surface of the tread 20 when the tire is in normal use. The second layer 36 is made of the second extruded component 26 and is between the first and third layers 34, 38. Longitudinal grooves exist in the tread 20 and extend through the second and third layers 36, 38 and terminate at the first layer 34, but do not extend through any of the first layers 34. It is contemplated that the tread 20 may be configured differently according to other embodiments such that there may be any number of layers, the longitudinal grooves may extend into/through any or all of the layers, and such that the layers need not all lie flat against each other, but may be thicker or thinner at some point, or may be located between other locations of adjacent layers.

In fig. 4, all three layers 34, 36, 48 directly face the ground 18, and in other embodiments, possibly all layers 24,26, 28 of the tread 20 directly face the ground 18 upon exiting the mold 22. If an object is between the ground 18 and the tread 20, it can be said that the three layers 34, 36, 38 are all the same distance from the ground 18 in the vertical direction 40. In fig. 4, the various components of the extrusion system 10 are not shown for clarity, and the elements shown are the tread 20 and the ground 18 to illustrate the relationship between these two objects at this point in the manufacturing process. The floor 18 will be defined as the floor or other horizontal surface of a construction plant, as distinguished from a foundation pit 42, which is an opening into the floor 18 in a vertical direction 40 to a pit depth 44. Referring again to fig. 3, the adjustment mechanism 48 engages the tread 20 in the space between the mold 22 and the conveyor 68 in the longitudinal direction. The illustrated adjustment mechanism 48 is a roller that pushes on top of the third layer 38 and rotates the tread 20 ninety degrees about its horizontal axis, which is the axis of the longitudinal direction, i.e., the direction the tread 20 travels out of the mold 22. The adjustment mechanism 48 need not be a roller in other embodiments, but may be any kind of device capable of rotating the tread 20 ninety degrees upon exiting the mold 22. In some cases, the adjustment mechanism 48 need not be a separate component, but may additionally or alternatively be a recess or orientation of the conveyor 68 or other conveying mechanism for conveying the tread 20 and changing its orientation relative to the ground 18. In other embodiments, the adjustment mechanism 48 is not required. Here, if it is desired to rotate the tread 20, the distance from the mold 22 to the conveyor 68 may be adjusted to find an optimal configuration to allow the tread 20 to rotate and be placed on the conveyor 68 in a desired orientation.

When the adjustment mechanism 48 is a roller, it may be spring loaded, or may otherwise provide sufficient force to the tread 20 to rotate it relative to the ground 18 to the position shown in fig. 5 at a point longitudinally behind the adjustment mechanism 48 and on the conveyor 68. In fig. 5, for clarity, the conveyor 68 and other components of the extrusion system 10 are not shown, but rather the tread 20 and ground 18 are shown to illustrate their relative orientations. The tread 20 is rotated so that its bottom layer, the first layer 34, is closest to the ground 18 in the vertical direction 18. The first layer 34 may face the ground 18 directly or, if the assembly is between it and the ground, such as a conveyor 68, the first layer 34 may be closer to the ground 18 in the vertical direction 40 than any other layer 34, 36 of the tread 20. When the tread 20 is incorporated into a tire, the third layer 38, which is the ground-engaging surface of the tire, is the layer of the tread 20 that is furthest from the ground 18 in the vertical direction 40 in FIG. 5. The rotation of the tread 20 corrects the orientation of the rear mold 22 caused by the horizontal orientation of the extruders 12,14, 16 so that the tread 20 is in the desired orientation after the co-extrusion process. However, it may be that one desires the tread 20 to maintain the orientation shown in fig. 3 at the point it exits the mold 22, and therefore does not include or use the adjustment mechanism 48, and the tread 20 is utilized in the fig. 4 orientation at a location downstream of the extrusion system 10.

Fig. 6 shows a left side view of the extrusion system 10 of fig. 3, with the support structure 46 shown holding the extruders 12,14, 16 above the floor 18 in the vertical direction 40. It can be seen that in fig. 6, the foundation pit 42 is not present and all portions of the first, second and third extrusion barrels 50,52, 54 are located above the ground 18 in the vertical direction 40. Further, no portion of the drive mechanisms 56, 58, 60 are located below the floor 18 and are spaced a distance from the floor 18 in the vertical direction 40. Further, the hoppers 62, 64, 66 or any portion of the extruded components 24,26, 28 are not below the floor 18 at any point and are spaced a distance from the floor 18 in the vertical direction 40. The extrusion system 10 is arranged such that all components of the extruder present, such as the drive mechanism, the extruder barrel, the hopper, and the extruded components being processed, are a distance above the floor 18 in the vertical direction 40.

A horizontal plane 70 extends through the center of the three barrels 50,52, 54 such that the horizontal plane 70 may extend through the axes 72, 74, 76 of the extrusion screws in the three barrels 50,52, 54. In this regard, the three extruder barrels 50,52, and 54 may be described as being oriented in a horizontal plane 70, and in fact the three extruders 12,14, 16 may be described as being oriented in the horizontal plane 70, as they each have components within a common horizontal plane 70. The horizontal plane 70 also extends through the three drive mechanisms 55, 58, 60 such that they are also all located within the common horizontal plane 70. The horizontal surface 70 is spaced a distance from the ground 18 in the vertical direction 40 and is not located within the foundation pit 42. The support structure 46 supports the extrusion barrels 50,52, 54, and the support structure 46 is also not located in the foundation pit 42. The support structure 46 need not be a single structure, but may be a plurality of structures that are located on the floor 18 and support the various barrels 50,52, 54 and may or may not be engaged with each other. Support structure 46, or any portion thereof, may not be placed within foundation pit 42.

In order to be located in the same horizontal plane 70, it is not necessary that all axes 72, 74, 76 of the extrusion screws of all of the extrusion barrels 50,52, 54 are located within the same horizontal plane 70. Instead, it is simply the case that the common horizontal plane 70 extends through at least a portion of each barrel 50,52, 54. The horizontal plane 70 may extend through the upper portion of the first barrel 50, but miss the extrusion screw axis 72 of the first barrel 50, then extend through the extrusion screw axis 74 of the second barrel 52, then pass through the lower portion of the third barrel 54, miss the extrusion screw axis 76 thereof. In some embodiments, at least two of the extrusion barrels 50,52, or 54 share a common horizontal plane 70 that passes through a portion of at least two of them, while another extrusion barrel 50,52, or 54 in the extrusion system 10 is above or below the common horizontal plane 70, so it does not extend through any portion of them, but none of the extrusion barrels 50,52, 54 is located fully or even partially within the foundation pit 42. The horizontal surface 70 may be parallel to the floor 18 and spaced a distance from the floor 18 in the vertical direction 40. Other portions of the extrusion system 10 may or may not be in the horizontal plane 70, such as the tread 20, the mold 22, the conveyor 68, the adjustment mechanism 48, or the hoppers 62, 64, 66.

Fig. 7 illustrates a front view of the extrusion system 10, wherein a horizontal plane 70 extends through the axes 72, 74, 76 of the helical screws of the extrusion barrels 50,52, 54, the drive mechanisms 56, 58, 60, the mold 22, the tread 20, and the extruded components 24,26, 28. Leaving the mold 22, only the first layer 34 is visible, but once the tread 20 is rotated by the adjustment mechanism 48, all three layers 34, 36, 38 are visible, with the first layer 34 now at the bottom and the third layer 38 at the top in the vertical direction 40. It can be seen that rotation of the tread 20 is accomplished by the adjustment mechanism 48, rotating it 90 degrees from its direction away from the mold 22, and then placing it on the conveyor 68.

Although shown and described as employing three extruders 12,14, 16 having three extrusion barrels 50,52, 54, it should be understood that the extrusion system 10 may include any number of extruders having extrusion barrels, so long as they are two or more in number to form a co-extrusion process. Orienting the barrels 50,52, 54 into a common horizontal plane 70 eliminates the need for a foundation pit 42 and a large support structure 46 for supporting the extruders 12,14, 16. With the extruders 12,14, 16 at the floor, it is much easier to supply the extrusion components 24,26, 28 to the respective hoppers 62, 64, 66 and is common to each extruder 12,14, 16. The loading of the tool is more ergonomic and may improve safety by reducing or eliminating product paths above the operator work area.

While the invention has been described in connection with certain preferred embodiments, it is to be understood that the subject matter encompassed by way of the invention is not limited to those specific embodiments. On the contrary, it is intended that the subject matter of the invention embrace all alternatives, modifications and equivalents as may be included within the spirit and scope of the appended claims.