阅读说明：本技术 注射单元和成型机 (Injection unit and molding machine ) 是由 C·巴尔卡 F·迪尔奈德 S·埃皮希 G·哈格尔 于 2020-03-20 设计创作，主要内容包括：本发明涉及一种用于成型机的注射单元,包括：注射活塞；注射驱动器；传动系,用于将注射力从注射驱动器传递到注射活塞上；用于测量注射力的测量装置,其具有至少一个测量体；处理器,其配置用于输出作为计算的结果的力信号；其中,设置有允许处理器计算不受温度影响影响的力信号的器件,该器件构造为用于至少一个测量体的、与至少一个测量体不同的支承件,至少一个测量体通过支承件支承在传动系中,由注射驱动器产生的力能够通过支承件传递,且支承件允许至少一个测量体的由温度影响引起的变形,从而至少一个测量体的应力状态在没有由注射驱动器产生的力的情况下至少在至少一个传感器的位置处至少基本上保持不变。(The invention relates to an injection unit for a molding machine, comprising: an injection piston; an injection driver; a drive train for transmitting an injection force from the injection drive to the injection piston; a measuring device for measuring an injection force, having at least one measuring body; a processor configured to output a force signal as a result of the calculation; wherein means are provided which allow the processor to calculate a force signal which is not influenced by temperature effects, which means are configured as a support for the at least one measuring body which is different from the at least one measuring body, by means of which support the at least one measuring body is supported in the drive train, by means of which support the force generated by the injection drive can be transmitted, and which support allows a deformation of the at least one measuring body caused by temperature effects, so that the stress state of the at least one measuring body remains at least substantially unchanged without the force generated by the injection drive, at least at the location of the at least one sensor.)

1. Injection unit (8) for a moulding machine, comprising:

-an injection piston (2) movably supported in a cylinder (1) by applying an injection force for injecting a melt of a molded part located in the cylinder (1) into a mold of a molding machine;

-an injection driver (3) for generating an injection force;

-a drive train between the injection driver (3) and the injection piston (2) for transmitting an injection force from the injection driver (3) to the injection piston (2);

-a measuring device arranged in the drive train for measuring the injection force, wherein the measuring device has at least one elastically deformable measuring body by means of which a force generated by the injection drive (3) can be transmitted to the injection piston (2) in the event of a change in the stress state of the at least one measuring body and the change in the stress state of the measuring body can be measured by at least one sensor (5) of the measuring device,

-a processor (6) for calculating the transferred force, to which the signal of the at least one sensor (5) can be supplied, wherein the processor (6) is configured for outputting a force signal as a result of the calculation;

wherein means are provided which allow the processor (6) to calculate a force signal which is not influenced by temperature effects, characterized in that the means are configured as a support (7) for the at least one measuring body which is different from the at least one measuring body, wherein the at least one measuring body is supported in the drive train by the support (7) and the force generated by the injection drive (3) can be transmitted through the support (7), and the support (7) allows a deformation of the at least one measuring body caused by temperature effects, such that the stress state of the at least one measuring body remains at least substantially unchanged without the force generated by the injection drive (3), at least at the location of the at least one sensor (5).

2. Injection unit according to claim 1, wherein the support (7) has a first region (71) and a second region (72), with the first region being connected with another component of the drive train and with the second region being connected with the at least one measuring body.

3. Injection unit according to claim 2, wherein the support (7) is constructed in the form of a plate hinge.

4. Injection unit according to claim 2, wherein a hinge (73), preferably a solid hinge, is arranged between the first and second regions (71, 72).

5. Injection unit according to claim 4, wherein the first and second regions (71, 72) are each configured in the form of a ring and are connected to one another, preferably only, force-transmitting by means of at least two hinges.

6. The injection unit according to claim 4 or 5, wherein the hinge is a solid hinge in the form of a fan fold.

7. Injection unit according to at least one of the preceding claims, wherein the at least one measuring body is configured in the form of a measuring membrane (4) having an outer flange (41), an inner flange (42) and a web (43) connecting the outer and inner flanges (41, 42), wherein the forces transmitted through the drive train can be conducted from one flange (41, 42) to the other flange (41, 42) via the web (43), and wherein the at least one sensor (5) is provided for measuring a deformation of the web (43).

8. Injection unit according to claim 7, wherein two sensors (5) are provided on two surfaces of the tab (43) which are spaced apart from each other in the axial direction, such that the two sensors are congruent to each other in a top view of the tab (43) in the axial direction.

9. Injection unit according to at least one of the preceding claims, wherein a machine controller (15) of the injection unit (8) is configured for controlling or adjusting an injection process based on the force signal.

10. Moulding machine, in particular plastic injection moulding machine, having at least one injection unit (8) according to at least one of the preceding claims.

Technical Field

The present invention relates to an injection unit having the features of the preamble of claim 1 and to a molding machine having at least one such injection unit.

Background

A common embodiment of an injection unit usually has at least one cylinder with at least one injection piston, which in the case of an injection unit for a plastic injection molding machine is usually configured in the form of a rotatable and movable plasticizing screw. For plasticizing, the plasticizing screw can be moved in rotation and, for injecting the molded part melt into the mold of the plastic injection molding machine, can be moved in translation by an injection drive.

In order to be able to set the injection cycle as precisely and reproducibly as possible, it is necessary to be able to determine the forces and pressures acting during the injection as precisely as possible. For this purpose, a measuring device can be used to measure the force acting axially on the injection piston. The measuring device has at least one measuring body by means of which the force generated by the injection drive can be transmitted to the injection piston when the mechanical stress state of the at least one measuring body changes, and the change in the stress state of the measuring body can be measured by means of at least one sensor of the measuring device. A processor for calculating the transmitted force is provided, to which the signal of the at least one sensor can be supplied, wherein the processor is configured to output a force signal as a result of the calculation.

An injection unit is for example shown by EP 0752303B 1. The extension of the material caused by the change in the state of stress is measured, these variables being proportional to each other according to hooke's law. The stretching or twisting may be detected, for example, by strain gauges or piezoelectric sensors. However, the stretching can also be carried out by displacement measurement by relative displacement of two different points on the surface of the measuring body, in particular by using a piezoresistive-based micro-electromechanical sensor (MEMS).

The measuring body of the injection unit can be integrated into the drive train (or force transmission device, Kraftstrang) in various ways. There is always the problem that, due to installation and temperature influences, stresses may occur in the measuring body which distort the force signal output by the processor (these stresses are then not only proportional to this force). The stresses resulting from the mounting can be determined and taken into account by verification (calibration, zeroing) of the measuring body. This is not applicable to stresses due to temperature effects. Distortion (or falsification) of the force signal leads to undesired process fluctuations during the injection process.

Disclosure of Invention

It is an object of the present invention to provide a universal injection unit and a molding machine having at least one such injection unit in which the above-mentioned problems are avoided.

This object is achieved by an injection unit having the features of claim 1 and a molding machine having at least one such injection unit. Advantageous embodiments of the invention are defined in the dependent claims.

Since means are provided which allow the processor to calculate a force signal which is not affected by temperature, distortion of the force signal and thus undesired process fluctuations can be avoided in the present invention. The force signal can be used in a known manner to control or regulate the force and pressure acting during the injection.

It should be noted that the terms "" stress state of the measuring body "and" deformation of the measuring body "are used equally in the present disclosure, since hooke's law applies within the scope of application of the invention and the mechanical stress in the measuring body and the deformation resulting therefrom are proportional to one another (with a proportionality constant characterizing the measuring body, which proportionality constant is known from the delivery specifications of the measuring or measuring body).

The invention provides that the device is designed as a support for the at least one measuring body which is different from the at least one measuring body (i.e. not in one piece, but in the form of two components), wherein the at least one measuring body is supported in the drive train by means of the support, and the support allows a deformation of the at least one measuring body due to temperature effects, such that the stress state of the at least one measuring body remains at least substantially unchanged without forces generated by the injection drive, at least at the location of the at least one sensor. It is therefore not essential that the stress state does not change due to temperature effects in the region of the entire at least one measuring body, but only the position of the at least one sensor of the measuring device is decisive.

In one embodiment of the invention, it is provided that the support has a first region, with which the support is connected to the at least one measuring body, and a second region, with which the support is connected to a further component of the drive train.

Provision can be made for the support to be constructed in the form of a plate hinge. This allows planar motion in two linearly independent spatial directions.

Provision may be made for a hinge, preferably a solid hinge (for example in the form of a fan fold (Leporellos)), to be arranged between the first region and the second region.

Preferably, the first region and the second region of the bearing are each designed in the form of a ring and are connected to one another (preferably exclusively) in a force-transmitting manner via at least two hinges.

An embodiment makes it possible to introduce the force action point of a temperature-dependent force (for example, the frictional force of the seal, the deformation force of the damping element, etc.) acting on the at least one measuring body alternately (in the direction of the force during the transmission of the injection force) into the at least one measuring body before or after the at least one sensor. This makes it possible to mechanically remove temperature-dependent influences from the measuring chain.

In one embodiment of the invention, it is provided that the at least one measuring body is designed in the form of a measuring membrane having an outer flange, an inner flange and a web connecting the outer flange and the inner flange, wherein forces transmitted via the drive train can be conducted from one flange to the other flange via the web, and that the at least one sensor is provided for measuring a deformation of the web. In the case of a measuring membrane, it is sufficient if the support allows a deformation of the measuring membrane in the radial direction due to temperature effects (deformation of the measuring membrane in the axial direction due to temperature effects can be neglected).

It can be provided that the webs and/or the inner and/or outer flanges are designed in the form of a closed ring.

Provision is preferably made for the measuring membrane to be made in one piece (preferably made of metal). Alternatively, however, it can also be provided that the membrane is of multi-part design, wherein the webs, the outer flange and/or the inner flange are designed as separately produced (preferably made of metal) components.

Particularly preferably, the inner flange and/or the outer flange have axially aligned (preferably regularly arranged to each other) fastening openings. These fixing holes can be used, for example, for fixing the measuring membrane by means of a screw connection or a screw connection.

The at least one sensor for measuring changes in the stress state of the measuring body can be configured in the form of a strain gauge. Alternatively or additionally, however, piezoelectric sensors or piezo-mechanically constrained micromechanical sensors may also be provided.

One embodiment of the invention shows a measuring membrane comprising two fastening rings (inner and outer flange) and a web between the two fastening rings, which web has at least two sensors, wherein one sensor is mounted on the web opposite to the other sensor (congruent one above the other in an axial plan view). By such an arrangement of at least two sensors, the normal stress on the tab surface can be divided in the radial direction into a part in the same direction and a part in the opposite direction. The portion in the opposite direction then corresponds to the bending of the measuring membrane and is substantially proportional to the injection force to be measured. The same direction portion is substantially caused by the temperature difference at the radially inner cylindrical surface and the radially outer cylindrical surface of the measuring membrane. The measured values are therefore corrected for deviations caused by the temperature field.

The present invention can be used, for example, in molding machines in the form of an injection molding machine (preferably, a plastic injection molding machine), a press machine, and the like.

In one embodiment, the processor may be located in the machine controller of the injection unit or the entire molding machine. Other control or regulation processes may be run on the processor with respect to the injection unit and/or the entire molding machine. Alternatively, the processor may be provided separately from the machine controller, in particular also separately from the injection unit and/or the entire molding machine, for example in the cloud.

Drawings

Embodiments of the invention are discussed with reference to the figures. It shows that:

FIGS. 1a, b illustrate one embodiment of the present invention;

FIG. 2 shows a schematic of the present invention;

FIG. 3 shows details of one embodiment of the present invention;

FIGS. 4a-d show different views of another embodiment of the present invention;

FIG. 5 shows another embodiment of the present invention;

fig. 6a, b show a further embodiment of the invention in different views;

FIG. 7 shows details of one embodiment of the present invention;

fig. 8 shows a perspective view of a measuring body in the form of a measuring membrane.

Detailed Description

In the figures, the lines for transmitting the signals of the sensor 5 to the processor 6 are not shown for the sake of clarity.

Fig. 1 shows an embodiment of an injection unit 8 for a molding machine, wherein an injection piston 2 in the form of a plasticizing screw is arranged in a cylinder 1.

For driving the plasticizing screw in a rotary motion, a metering drive 11 is provided, which is connected to the plasticizing screw by means of a drive train 9, which comprises a belt and a belt pulley. The plasticizing screw is arranged together with a metering drive 11 on an injection bridge 10, which can be moved together by the injection drive 3.

The injection drive 3 is embodied here in a manner known per se as a spindle drive, which has a fixed nut 31 and a spindle 32. A drive device for driving the rotatably mounted spindle 32 is not shown. Of course, injection drivers 3 of different designs may also be provided.

The measuring membrane 4 (see also fig. 8) forming the measuring body in this exemplary embodiment has an outer flange 41 and an inner flange 42, which are connected to one another by a web 43, wherein the outer flange 41, the inner flange 42 and the web 43 are formed in one piece from a metallic material.

Fig. 1b shows a detailed view of fig. 1 a. The measuring membrane 4 is shown enlarged here, so that two sensors 5 (in this embodiment, configured as strain gauges) can be seen. The sensors 5 are arranged (by gluing in this case) on two surfaces of the web 43 which are spaced apart from one another in the axial direction in such a way that the sensors are congruent to one another in an axial plan view. With such an arrangement, normal stresses on the surface of the tab 43 can be divided in the radial direction into equally directed portions and oppositely directed portions.

Fig. 2 schematically shows how the processor 6 is in data transmission connection with a memory device 13, in which an experimentally determined or theoretically calculated relationship between the stress state of the at least one measuring body and the transmitted force is stored. Thus, the processor 6 can calculate and output (e.g. to the machine controller 15) a force signal (measured by the sensor 5) that is not affected by the measured temperature.

Fig. 3 and 4 show two different embodiments of the invention in different views.

Fig. 3 shows a detail of a one-piece, annular, rotationally symmetrical support 7, which has a first region 71, with which it is connected (here by means of the bolt 12) to the measuring body, and a second region 72, with which it is connected to another component of the drive train (here the axially projecting part 16 of the injection bridge 10). The first and second regions 71, 72 are connected to one another by a hinge 73, which is configured here as a solid hinge in the form of a fan fold. This configuration allows a (slight) radial deformation of the measuring body due to temperature effects.

In the exemplary embodiment of fig. 4a (sectional view of plane a-a of fig. 4b, but with the support 7 shown in fig. 4b in isolation), the support 7, which is constructed in one piece, likewise has a first region 71, by means of which it is connected to the measuring body (in this case the measuring membrane 4), and a second region 72, by means of which it is connected to another component of the drive train (in this case the axially projecting section 16 of the injection bridge 10). The first and second regions 71, 72 are in turn connected to one another by a total of four hinges 73, which are in this case designed as solid hinges in the form of webs with cutouts on both sides. This configuration also allows a (slight) radial deformation of the measuring body due to temperature effects.

As shown in the plan view of fig. 4b, the sectional view of fig. 4c (along the plane a-a of fig. 4 b) and the perspective view of fig. 4d, the first and second regions 71, 72 are each constructed in the shape of a ring having a plurality of openings through which the measuring body can be fixed by means of the bolts 12. Here, four hinges 73 are provided as an example, and more or fewer hinges 73 may be provided.

Fig. 5 shows an embodiment in which a plate 14 is arranged between the measuring membrane 4 and the injection driver 3. This serves to eliminate the displacement force of the cover from the measurement in the measuring membrane.

Fig. 6a shows a further example of a support 7 for the invention in a side view. The support 7 is connected on the one hand to the portion 16 of the injection bridge 10 and on the other hand (as shown in fig. 1 a) to the injection drive 3. The support is constructed in the form of a split rotationally symmetrical (or shared rotationally symmetrical) ring and has a hinge 73 in the form of a flexible hinge (or bending hinge). Fig. 6b shows a cross-sectional view along the line a-a in fig. 6 a.

Fig. 7 shows a further example of a two-part, rotationally symmetrical bearing 7 according to the invention in a perspective detailed view. The support 7 is designed in the form of a plate hinge and has an annular first region 71 for connection to the measuring body and an annular second region 72 for connection to a further component of the drive train of the injection drive 3. The inner region 71 is arranged so as to be radially movable but held fixed in the axial direction in a recess of the outer region 72, so that the support 7 allows the measuring membrane 4 to be deformed by temperature effects. The outer region 72 can be designed to be openable (for example in the form of two half-shells), so that the inner region 71 can be inserted into the recess. The arrangement of the support 7 between the measuring membrane 4 and the injection bridge 10 can be realized as shown in fig. 6.

List of reference numerals

1 Cylinder of injection Unit

2 injection piston of an injection unit

3 injection driver

31 nut of injection driver

32 injection driver spindle

4 measuring film

41 outer flange of measuring membrane

42 inner flange of measuring membrane

43 Tab for measuring film

5 sensor of measuring device

6 processor

7 support for a measuring body

71 first region of the support

72 second region of the support

73 hinge

8 injection unit

9 drive train of a metering drive

10 injection bridge

11 metering driver

12 bolt

13 storage device

14 board

15 machine controller

16 parts of injection bridge