injection molding machine

Abstract

Injection molding machine with a first stop element moved by a drive unit, wherein the first stop element impacts a second stop element during the injection molding process, and wherein a detection device (11) is provided, by which the force with which the first stop element (35) impacts the second stop element (36) can be measured and fed to a control device (31) via a transmission device (33), wherein the first stop element (35) comprises ejector pins (7) and a first stop surface (30) which can be moved, preferably translationally, by the drive unit and can be struck against the second stop element (36) arranged in or on an injection mold for the ejection process;and / or that the first stop element (35) has a first stop surface (30) arranged on a movably mounted mold clamping plate (8), which first stop surface can be struck by the drive unit for the closing process against a fixed mold clamping plate (8') comprising the second stop element (36), characterized in that the force with which the first stop element (35) impacts the second stop element (36) can be compared by the control device (31) with a reference value, wherein a braking device (38) for decelerating the first stop element and / or a drive element (2) operatively connected to the first stop element (35) can be controlled by the control device (31), wherein the deceleration by the braking device (38) can be changed depending on the difference between the force measured by the detection device (11) and the reference value.;

Description

[0001] The invention relates to an injection molding machine with a first stop element moved by a drive unit, wherein the first stop element impacts a second stop element during the injection molding process.

[0002] In injection molding machines, short production cycles require the deliberate collision of various, movably mounted components during the injection molding process, rather than allowing the corresponding components to approach each other slowly and leisurely. An example is the two mold halves of an injection molding tool that together form the cavity. These mold halves must be closed for the injection molding process. In this case, one mold half can act as the first stop element and impact the other mold half as the second stop element.

[0003] Another example is the ejector device of injection molding machines. Such ejector devices serve to eject semi-solidified or fully solidified injection-molded parts from the cavity formed by the two mold halves of an injection mold, also known as an injection molding tool. For this purpose, movably mounted ejector pins are arranged in the area of ​​the injection mold, with which the injection-molded parts can be ejected from the cavity of the injection mold. The ejector pins are connected to an ejector device and are moved by a drive unit of the ejector device. Such ejector pins are known in the art.

[0004] However, certain injection-molded parts can only be ejected from the ejector pins if the drive elements of the ejector device, which are moving during the ejection process, and the associated ejector pins, which are also moving, suddenly stop. This abrupt stop in movement and the associated acceleration can cause the injection-molded parts to fall out of the injection mold or off the ejector pins.

[0005] This sudden stop is generally made possible by one of the moving parts of the ejector device and the associated ejector pins impacting a stop surface of a stationary component of the injection molding machine at a certain speed. Particularly in electrically operated injection molding machines, the drive unit of the ejector device typically features a servo motor and other rotating parts, such as a spindle, various pulleys, and the like. Due to their high mass and the associated high moment of inertia that occurs during the movement, these parts exert large forces on the components in the power flow, i.e., between the drive unit and the ejector pins, in the event of an abrupt stop caused by impact with a stationary component and the associated movement to a mechanical end position.The spindle of a spindle drive and the bearings of the movably mounted parts of the drive unit are particularly sensitive to such loads and can be destroyed or at least damaged by excessive impact. This particularly affects the ball races of the bearings and the spindle. On the other hand, starting or impacting at a lower speed, or braking the moving parts of the ejector device too early or too sharply before impact and the associated reaching of the mechanical end position, means that certain injection-molded parts are not removed from the injection mold, which leads to an increase in cycle time because these injection-molded parts must be removed manually.

[0006] In order to avoid damage to the drive unit, in particular to the spindle of a spindle drive, target courses are provided for the moving stop element, wherein on the one hand the speed at which the movably mounted stop element is moved and on the other hand the point along the path of the moving stop element are specified and at which the drive unit stops driving the movably mounted stop element or a braking process is initiated to decelerate the first stop element and / or a drive element operatively connected to the stop element, which is supplied with energy by the drive unit and by which the first stop element is moved, for example by braking the stop element and / or the drive element by means of a braking device or by switching off or disconnecting an electric motor which supplies the energy required to move the stop element from the drive unit.Additionally, the end position of the stop element, at which the stop element is to come to a stop, can also be specified. In the case of active braking, the target curve can include so-called braking ramps, which specify the rate at which the moving stop element is to be decelerated.

[0007] Setting the target curve, in particular the maximum speed of the moving stop element and the point in time at which the drive is terminated or a braking process is initiated, is generally very difficult and also depends heavily on the corresponding framework conditions, such as the type of injection-molded parts to be produced. In general, an impact of this type, such as that which occurs during the ejection of injection-molded parts, results in extremely high forces. If the target curves for the moving stop element are incorrectly set, this can lead to the destruction of the stop element and the drive unit connected to it, because on the one hand the impact occurs at too high a speed, e.g.because the target position at which the first stop element should have come to a standstill is exceeded, or on the other hand the drive unit still tries to drive the movably mounted stop element, although the mechanical system has already been reached by the impact on the second stop element.

[0008] JP 2003-039 504 A shows an ejector device for an injection molding machine in which a spring acts as a damping element if the ejection stroke is incorrectly set. The spring is set to a certain preload so that spring actuation only occurs if the ejector pin impacts the ejector plate with excessive force. The actuation of the spring is detected by a photo sensor, whereupon the injection molding machine is stopped. The spring, together with the photo sensor, thus serves as an emergency stop switch if the impact force of the ejector pin is too high. However, only the exceeding of a reference value determined by the spring constant by the impact force is measured, and not the force itself. To adapt to future ejection processes, a differently dimensioned spring must be used. Intervention in an ongoing braking process is only possible by abruptly interrupting the injection molding process.These disadvantages are detrimental to the required flexibility of the injection molding machine for the production of a wide variety of injection-molded articles as well as the short cycle time.

[0009] DE 10 2009 037 697 A1 discloses the determination of the closing force in a molding device, wherein the closing force is determined on the basis of a minimum required closing force, so that it can be ensured that a closing force is exerted which is necessary for closing the molding device, but which is not so great that it damages the molding device.

[0010] US 2009 / 0 243 131 A1 discloses that the impact force of a movable plate on a stationary plate in a forming device is determined.

[0011] JP 2006 027 248 A discloses that the electric motor of an injection nozzle is braked when it has reached a predetermined position.

[0012] DE 603 ​​03 339 T2 discloses that an injection nozzle is brought to a stationary clamping plate of a forming machine, wherein the drive motor of the injection nozzle is stopped when a preset nozzle contact force is reached.

[0013] The object of the present invention is to avoid these disadvantages and to provide a device with which to prevent the destruction of components of the injection molding machine associated with a faulty impact.

[0014] This is made possible by an injection molding machine having the features of claim 1.

[0015] By providing a detection device according to the invention with which the force occurring upon impact of the first stop element driven by a drive unit against a second stop element or a measured variable associated with this force can be measured, it is possible to provide a parameter based on which the control device can initiate further processes of the injection molding machine with regard to the movement of the first stop element and / or the drive element. This parameter serves as a decision criterion and is connected to a transmission device of the

[0016] The control device can, for example, decide to initiate or intensify a braking action for the first stop element and / or for a drive element operatively connected to the stop element, or to allow the second stop element to deflect or yield as a result of the impact, or to modify future movement actions of the first stop element. The operative connection between the drive element and the first stop element allows the first stop element to be driven by the drive element and can, for example, be detachable and / or permit relative movement. The transmission device consists of conventional electronic components and signal transmission means.

[0017] The detection device can measure the force occurring during the impact directly or indirectly. The measured value can be an instantaneous value, a value averaged over a short period of time, or a maximum value occurring within that short period of time.

[0018] Further advantageous embodiments of the invention are defined in the dependent claims.

[0019] According to the invention, the control device comprises means for comparing the value measured by the detection device with a reference value, which may, for example, represent a maximum force. These means comprise known electronic components.

[0020] A braking device for decelerating the first stop element and / or a drive element connected to the first stop element can be controlled by the control device, wherein the braking force of the braking device is varied depending on the difference between the force measured by the detection device or the measured variable representing the force and the reference value. Thus, it can be provided to reduce the braking force if the detected force is lower than the reference value. The deceleration of the stop element and / or the drive element is reduced.

[0021] If the value measured by the detection device now exceeds the reference value, for example because the speed at which the first stop element impacted the second stop element was too high or the braking process for the first stop element was initiated too late or occurred with too low a deceleration rate, the control device controls a braking device in order to initiate or intensify braking of the first stop element and / or the drive element operatively connected to the first stop element.

[0022] For these purposes, a further transmission device is provided, by means of which the control device can transmit a corresponding signal to the braking device. The further transmission device consists of known electronic components and signal transmission means.

[0023] It can also be provided that the detection device integrates the force acting during the impact by means of a calculation unit comprising suitable electronic components, such as a processor, and compares this with the reference value of an integrated force. This is relevant if, for example, due to a malfunction, the drive unit attempts to drive the first stop element even after the latter has already impacted the second stop element and reached a mechanical end position. In this case, the destructive effect on the components of the injection molding machine is not necessarily achieved by a single force peak, but by the application of force over an excessively long period of time. This can, for example, destroy the motor of the drive unit.

[0024] The deceleration of the moving first stop element can be achieved by active braking with a suitable braking device. This includes hydraulic or pneumatic braking elements, as well as devices that can reduce the speed of an electric motor or reverse its direction of rotation.

[0025] However, it is also possible for the braking device to serve only to terminate active driving of the first stop element, whereupon the latter decelerates automatically as a result of the friction acting on it. In this case, the braking device can comprise a device for interrupting the power supply to the motor or for decoupled from the drive unit. It is also possible for the braking device to have passive braking elements for decelerating the first stop element.

[0026] The necessary electrical and electronic components for the measurement by means of the detection device, as well as for the comparison with the reference value, as well as the means for transmitting the control signals to the braking device are known in the prior art.

[0027] In addition to or as an alternative to changing the current braking process, the detection device can influence the future course of the impact of the first stop element on the second stop element by modifying target courses for the movement of the first stop element stored in an electronic memory depending on the measured impact force or detected measured variable. If the reference value is exceeded, the target courses are modified in such a way that a greater deceleration and / or an earlier initiation of the braking process occurs. If the reference value is undershot, the target courses can be modified in such a way that a lesser deceleration and / or a later initiation of the braking process occurs. The magnitude of the difference between the measured value and the reference value can also be incorporated into the modification. The future courses of the impact then occur according to the modified target courses.This makes it easy to modify the control of future injection molding processes without having to replace mechanical components, such as an undersized damping spring.

[0028] In one embodiment of the invention, the control device has an emergency stop device, preferably in the form of a circuit breaker, with which the drive unit can be switched off immediately.

[0029] In one embodiment of the invention, the detection device comprises a vibration measuring device with which vibrations of the first and / or second stop element can be measured, since upon impact of the first stop element on the second stop element, the first and second stop elements are set into vibration. The amplitude of these vibrations is a measure of the force generated during the impact. Additionally or alternatively, the detection device can comprise a deformation measuring device, e.g. a strain gauge, for measuring a deformation of the first and / or second stop element resulting from the impact of the first on the second stop element. This deformation is usually reversible, since the first stop element and the second stop element are made of an at least partially elastic material, such as metal.Such deformation is also a measure of the impact force of the first stop element hitting the second stop element. Proximity sensors, such as inductive sensors, touch sensors, and the like, also serve as vibration measuring devices or deformation measuring devices.

[0030] The detection device may also include a sensor that measures the current drawn by an electric motor or a change in motor speed, which can also serve as a measure of the impact force. In the case of a hydraulic or pneumatic injection molding machine, the detection device may include a sensor for the pressure in the hydraulic or pneumatic system, which can also serve as a measure of the impact force.

[0031] In one embodiment of the invention, the detection device comprises a measuring device for measuring a damping force generated by damping the impact of the first stop element on the second stop element. If this damping is achieved by means of a spring, this measuring device can be designed to measure the spring force, for example, by measuring the compression of the spring. The extent of compression and / or the speed at which the spring is compressed can be measured.

[0032] Such measuring devices are provided, for example, by inductive sensors, light barrier sensors, etc. It can be provided that only the drive element operatively connected to the stop element is damped after the first has impacted the second stop element.

[0033] In a further embodiment, the control device has an electronic memory in which target curves for the movement of the first stop element are stored. These target curves contain the parameters relevant to the movement of the stop element, such as the acceleration, the maximum speed, the location or time at which a braking operation is initiated, and, if applicable, the rate at which the stop element is decelerated.

[0034] According to the invention, the target curves are modified depending on the measured variable determined by the detection device and stored in a modified form in the electronic memory for future injection molding processes. If the measured variable measured by the detection device exceeds the reference value, for example because an incorrect target curve was present or the settings of the injection molding machine are incorrect and thus the impact of the first stop element on the second stop element is too strong, the control device can correct this for subsequent processes and modify the target curve accordingly, thereby preventing repeated incorrect impact of the first stop element on the second stop element. The modification can be achieved, for example, by reducing the maximum speed of the first stop element or by initiating the braking process earlier or by braking more strongly.

[0035] On the other hand, if the measured variable measured by the detection device falls below the reference value by a critical amount, the target curve can also be changed by increasing the maximum speed of the first stop element or by initiating the braking process later or by braking less.

[0036] The invention further relates to an injection molding machine with a first stop element moved by a drive unit and a drive element operatively connected to the first stop element, and with a second stop element, wherein the first stop element impacts the second stop element during the injection molding process. The injection molding machine further comprises a braking device, which can be designed as described above, and a control device as described above. The drive unit, the first and second stop elements can also be designed as described above. The drive unit serves for the preferably translational movement of the drive element, which subsequently drives the first stop element.

[0037] According to the invention, the drive unit has an electric motor, wherein the energy transmitted from the electric motor to the drive unit can be reduced by the braking device.

[0038] For this purpose, the braking device comprises an electrical switching unit that, when the value measured by the detection device and compared with a reference value is exceeded, controls the electric motor to reduce the energy transmitted to the drive unit. This can be achieved by reducing the motor speed, changing the motor rotation direction, or interrupting or reducing the power supply to the motor. This decelerates the first stop element and / or the drive element operatively connected to the first stop element.

[0039] The invention relates to an injection molding machine with a first stop element moved by a drive unit and a drive element operatively connected to the first stop element, and with a second stop element, wherein the first stop element impacts the second stop element during the injection molding process. The injection molding machine further comprises a braking device, which can be designed as described above, and a control device as described above. The drive unit, the first and second stop elements, and the drive element can also be designed as described above.

[0040] According to the invention, the braking device comprises a hydraulic and / or pneumatic braking element with which the first stop element is braked. This is particularly relevant for hydraulic and / or pneumatic injection molding machines.

[0041] In one embodiment of the invention, the braking device comprises a damping element, which can be designed as a spring. This damping element can act as a passive braking element for the first stop element and / or the drive element. In this case, the detection device can have a measuring device for measuring the damping force generated by the impact of the first stop element on the second stop element and the associated damping. In the case of a spring, this can be done by measuring the spring compression.

[0042] The braking device is controlled via the control device and is activated depending on the detected impact force.

[0043] In one embodiment of the invention, the drive unit comprises a spindle drive with a spindle, which can also be assigned to the drive element.

[0044] The first stop element is part of an ejector device and comprises ejector pins and a first stop surface, which are preferably movable in a translational manner by the drive unit and which, for the purpose of the ejection process, strike or impact a second stop element arranged in or on the injection mold.

[0045] Additionally or alternatively, the first stop element is part of the injection mold and has a first stop surface arranged on a movably mounted mold clamping plate, which strikes or impacts a fixed mold clamping plate comprising the second stop element by the drive unit for the closing process.

[0046] In one embodiment of the invention, the injection molding machine has a sliding element for driving the first stop element, wherein the sliding element is mounted so as to be movable in translation relative to the drive element to a limited extent and thereby provides a reserve stroke for the drive unit when the first stop element has moved into its mechanical end position determined by the impact location.

[0047] A guide element connected to the drive element can be provided for the sliding element, wherein the sliding element is mounted for limited translational movement relative to the guide element and is guided by the guide element. A damping device, preferably a spring, can be arranged in the guide element to reduce the kinetic energy of the drive unit during the reserve stroke—i.e., during the overtravel of the drive unit—by damping its movement. Fig. 1 a cross-sectional view to explain the operating principle of an ejector device including the ejector pins connected to it, Fig. 2 a sectional view of an ejector device, Fig. 3a, Fig. 3b Detailed views of the Fig. 2 marked area, Fig. 4 a schematic representation of a control device according to the invention in connection with an injection molding machine. Fig. 5 a target course and a modified target course for the movement of the first stop element, Fig. 6 an embodiment of a detection device for the impact force of the first stop element on the second stop element, Fig. 7 shows a further embodiment of a detection device for the impact force of the first stop element on the second stop element, Fig. 8 shows a further embodiment of a detection device for the impact force of the first stop element on the second stop element, Fig. 9 shows a further embodiment of a detection device for the impact force of the first stop element on the second stop element, Fig. 10 shows a further embodiment of a detection device for the impact force of the first stop element on the second stop element, Fig. 11 shows a further embodiment of a detection device for the impact force of the first stop element on the second stop element, and Fig. 12a, Fig. 12b is a schematic representation of the closing side of an injection molding machine, wherein the first and second stop elements comprise the closing mold halves of an injection mold.

[0048] In Fig. 1 shows how an injection-molded part is produced in the cavity 27 of the injection mold, wherein the closed cavity 27 is formed by the movable mold clamping plates 8 and fixed mold clamping plates 8' and via the recess 25 for an injection nozzle by means of which plastic melt can be injected into the cavity 27.

[0049] The one in the Fig. 1 part of the injection molding machine with the ejector device 1 arranged to the left of the movable mold clamping plate 8 is based on the Fig. 2 and Fig. 3 explained.

[0050] After the plastic melt in the cavity 27 has at least partially solidified, the injection mold is opened so that the injection-molded part can be removed from the mold halves. For this purpose, a stop plate 28 is connected to the coupling piece 6 via a connecting element 26. The stop plate serves as a carrier for a total of three ejector pins 7. If the drive element 2 moves in the direction of arrow B, this movement is transmitted via the spring 4 to the sliding element 5, the stop plate 28, and the ejector pins 7.

[0051] Particularly when the plastic melt has not yet fully solidified, it may happen that the injection-molded part does not fall off the ejector pins 7. As the injection-molded parts cool down due to the opening injection mold, they shrink onto the ejector pins 7, making it difficult to release the injection-molded parts from the ejector pins 7. For this purpose, the stop plate 28 is moved at high speed towards the injection mold so that the first stop surface 30 impacts the second stop surface 29 and the ejector pins 7 stop abruptly. As a result, the injection-molded part falls off the ejector pins 7 due to the high acceleration that occurs. The stop plate 28 with the first stop surface 30 and the ejector pins 7 are part of the first stop element 35, which impacts the second stop element 36, which comprises the second stop surface 29.

[0052] The location of the standstill of the first stop element 35 is determined by a braking device 38 or the impact location of the first stop surface 30 on the second stop surface 29 and defines the mechanical end position of the ejector pins 7 or the sliding element 5. If an active braking device is provided for reaching the mechanical end position, this position can be determined beforehand by traveling, so that the mechanical stroke of the ejector pins 7 is determined and stored as a target curve 32 in an electronic memory.

[0053] Fig. Figure 2 shows an arrangement of an ejector device 1, which ejects an injection-molded part produced in an injection mold via ejector pins 7 (not shown in this figure). The ejector device 1 has an electric motor 13 having a belt drive which drives a spindle 2' by means of a belt 14 and a pulley 15, which is connected in a rotationally fixed manner to a spindle nut 17 via screws 16 and 16'. The spindle 2' and the ejector plate 9, which is firmly connected to the spindle 2' and is guided by a guide pin 10 during the translational movement, are parts of the translationally movable drive element 2. The parts of the ejector device 1 connected to the drive element 2, in particular to the spindle 2', are moved translationally relative to the injection mold, i.e., the injection mold, during the ejection process.A sleeve-shaped guide element 3 is attached to the ejector plate 9, in which the bolt-like sliding element 5 is mounted for limited translational movement relative to the guide element 3. The ejector device 1 is designed as an ejector coupling, wherein the sliding element 5 can be coupled to a coupling piece 6, wherein the coupling piece 6 can be releasably connected to the sliding element 5 via the claw 12.

[0054] Not shown in this figure are the ejector pins 7, which are connected to the coupling piece 6 and are arranged in or on the mold clamping plate 8, which is part of the injection mold. If the sliding element 5 with the connected coupling piece 6 is moved toward the mold clamping plate 8, their movement is transferred to the stop plate 28 and the ejector pins 7, which can be moved up to a second stop surface 29 (also not shown), which defines the mechanical end position.

[0055] To transmit the force transmitted from the electric motor 13 and the belt drive to the spindle 2, the sliding element 5 can be firmly connected to the ejector plate 9. In contrast, in the illustrated ejector device 1, a damping element 4 in the form of a spring 4 is arranged between the ejector plate 9 and the sliding element 5 in the guide element 3. The sliding element 5 is thus spring-loaded, whereby the movement of the spindle 2' and the ejector plate 9 can be transmitted to the sliding element 5 and thus, via the coupling piece 6, to the ejector pins 7. The preload can correspond to the rated load of the electric motor 13.

[0056] The stop plate 28 and the ejector pins 7 and thus also the sliding element 5 can be moved at high speed onto the second stop surface 29 of the second stop element 36 and impact thereon, whereupon the ejector pins 7 and the sliding element 5 stop abruptly, whereby a high acceleration and a high jerk are transmitted, so that the injection-molded parts can fall off the ejector pins 7.

[0057] Such an impact, due to the high inertia of the drive element 2, i.e., among other things, the spindle 2' and the ejector plate 9, leads to a high load on the spindle 2' and in particular on the bearings 18, 18' of the spindle nut. To avoid such loads and the associated damage, the spindle 2' and the ejector plate 9 can be moved even further when the sliding element 5 is already stationary due to the limited relative mobility of the sliding element 5 relative to the guide element 3. In this process, the spring 4 is compressed, and the spindle 2' and the ejector plate 9 are slowly and gently decelerated. The space between the sliding element 5 and the ejector plate 9 thus forms a follow-up and a reserve stroke for the drive element 2, in particular the spindle 2' and the ejector plate 9.

[0058] The drive element 2 is moved by the electric motor 13 from a control device 31 according to a target curve 32 stored in an electronic memory of the control device 31. This movement is transmitted via the spring 4 and the sliding element 5 to the stop plate 28 and the ejector pins 7 and thus to the first stop element. If, due to an incorrect setting, the time at which the braking of the first stop element is initiated is too late, so that the drive element 2 presses with high force against the first stop element after the latter has already impacted the second stop element and reached its mechanical end position, this can lead to the destruction of the aforementioned components and thus the entire injection molding machine. However, the spring 4 can also be adjusted such that compression only occurs in the event of an excessive impact force.

[0059] A detection device 11 serves to monitor the compression of the spring 4. As soon as the sliding element 5, which is operatively connected to the spring 4, exceeds a certain position, a braking process is initiated by a braking device 38, which is not shown in this figure. The compression of the spring 4 is a measure of the force with which the first stop element 35, i.e., the stop plate 28, impacted the second stop element 36, specifically the second stop surface 29. For this purpose, the detection device 11 has a sensor, which can be, for example, an inductive sensor or a light sensor. The detection device 11 has a calculation unit 37, by means of which the measured value can be compared with a reference value. If this reference value is exceeded, the braking device is controlled and activated by the control device 31 via the transmission device 33.The braking device 38 can, for example, shut down the electric motor 13, reduce the motor speed, or initiate a reversal of the direction of rotation of the motor 13. Furthermore, the calculation unit 37 can modify the target curve 32 for the movement of the first stop element 35 and initiate the braking time earlier, or increase the braking rate, so that future exceedances of the reference value can be avoided.

[0060] In the detailed view of the Fig. 3a, which Fig. 2 shows the area marked A, a recess 6' can be seen in the coupling piece, through which the ejector pins 7 can be fastened to the coupling piece by means of a screw. A sensor element 21 also serves as a bolt to prevent the sliding element 5 from rotating. Also visible are stop surfaces 19 of the guide element 3, which limit the mobility of the sliding element 5 relative to the sleeve-like guide element 3, so that during the ejection process a certain preload of the spring 4 is available for spring loading of the sliding element 5, and the head 20 of the sliding element 5 rests against these stop surfaces 19. The sliding element 5 is thus designed as a stop bolt that can strike the stop surfaces 19 of the guide element 3.

[0061] The sensor element 21 can have a mirror with which a light signal generated by the detection device 11 is reflected. If, as a result of the compression of the spring 4, the sensor element 21 shifts relative to the part of the detection device 11 fixedly mounted on the ejector plate 9, this light signal can no longer be reflected. In particular, the speed at which the sensor element 21 is moved out of the detection field of the detector device 11 is a measure of the impact force of the first stop element 35 on the second stop element 36. Instead of a mirror, the sensor element 21 can also be designed as part of an inductive sensor for the detection device 11.

[0062] Fig. 3b shows the same representation as Fig. 3a, only with the sliding element 5 and coupling piece 6 now connected via the claw 12, as well as the connecting element 26 fastened to the coupling piece 6. The electric motor 13 drives the spindle 2' and the drive element 2 comprising the ejector plate 9, so that the ejector plate 9 is moved translationally along the longitudinal direction of the guide pin 10 by means of the guide pin 10.

[0063] Fig. 4 shows a schematic representation of a control device 31 according to the invention in connection with an injection molding machine 34, which has a first stop element 35 and a second stop element 36, wherein the first stop element 35 impacts on the second stop element 36 during an injection molding process, for example to eject the produced injection-molded parts or to close the mold halves 8, 8'.

[0064] The impact force or a related measured variable is measured by a detection device 11, which is part of the control device 31. This is symbolized by the dashed line between the first stop element 35 and the detection device 11. A calculation unit 37 compares the measured variable with a reference value. If the reference value is exceeded, the control device 31 controls a braking device 38 via the transmission device 33, which initiates a braking process of the first stop element 35 or amplifies an already existing braking process. For this purpose, the braking device 38 is connected, for example, to the electric motor 13 and has control devices with which the electric motor can be controlled, e.g., its direction of rotation can be reversed. The braking device 38 can also have hydraulic and / or pneumatic braking elements.In addition to the detection device 11, the transmission device 33, and the calculation unit 37, the control device 31 comprises other known electrical and electronic components. These elements can be connected via known connecting means, such as signal lines, or can be arranged at least partially together on a circuit board.

[0065] Fig. 5 shows a modification of a target curve 32 for the movement of the first stop element 35 as a result of an excessive impact force measured by the detection device 11. A target curve 32 for the movement of the first stop element 35 is stored in an electronic memory of the control device 31 of the injection molding machine 34. The braking ramp begins at time 22, with the first stop element 35 being decelerated at a certain rate. If measurement with the detection device 11 reveals that the impact force on the second stop element 36 is too high, or if the first stop element 35 is driven when it is already in its mechanical end position, an earlier time 23 can be selected to initiate the braking process. Additionally or alternatively, it is possible to intensify the braking process and provide a higher braking rate—represented by the steeper braking ramp 24.As a result, the first stop element 35 comes to a standstill earlier both in time and space, and damage to parts of the injection molding machine 34 can be avoided.

[0066] Fig. 6 shows an embodiment of a detection device 11. The motor 13 is connected via belts 14 to the first stop element 35 to be moved. The electric motor 13 is connected to a motor rocker 38, which is mounted for at least limited rotation about an axis 39. In addition, the detection device 11 is arranged in the region of the electric motor 13, wherein a sensor element 21, for example an inductive sensor, is acted upon by a spring 40 and is fixed to a housing part different from the electric motor 13. The preload of the spring 40 adjusts the distance between the sensor element 21 and a measuring plate 41, which is fixedly connected to the electric motor 13. The preload of the spring 40 is selected such that the sensor element 21 assumes a reference distance from the measuring plate 41 when the electric motor 13 is under nominal load.

[0067] If the electric motor 13 is now loaded beyond its rated load, for example because the impact force exceeds a critical value, or because the first stop element 35 rests against the second stop element 36 after impact, thus impeding further movement of the first stop element 35 by the second stop element 36 despite the electric motor 13 being driven, the electric motor 13 is rotated about the axis 39 by the rotatable bearing of the electric motor 13, so that the distance between the measuring plate 41 and the sensor element 21 changes. This change can be detected and transmitted via the control device 31 and the transmission device 33 to a braking device 38. This can then reduce the motor power or switch off the electric motor 13 or reverse its direction of rotation.

[0068] Fig. Figure 7 shows a partially cutaway view of another embodiment of a detection device 11 according to the invention with a deformation measuring device. A measuring membrane 42 with a strain gauge 43 is arranged on the spindle 2'. The measuring membrane 42 is partially bridge-shaped and has a measuring plate 41 in the region of the ejector plate 9. The sensor element 21, for example, as an inductive sensor, is arranged in the ejector plate 9. As a result of an excessive impact force or driving the spindle 2' when the first stop element 35 is already resting against the second stop element 36 after the impact, the measuring membrane 42, in particular the strain gauge 43, is deformed. This deformation displaces the measuring plate 41 relative to the sensor element 42. This relative movement is detected and transmitted by the control device 31 via the transmission device 33 to the braking device 38.

[0069] Fig. Figure 8 shows a further embodiment of a detection device 11 according to the invention, wherein a pretensioning wheel 44 for the belt 14 is loaded by a spring 40. The load on the electric motor 13 and thus the overload resulting from an excessive impact force is reflected in the tension of the belt 14, causing the spring 40 to compress excessively. This can be detected by a sensor element 21 and transmitted to the braking device 38.

[0070] Fig. 9 shows a partially broken-away view of one half of an ejector device 1, a further embodiment of a detection device 11. A spring 40 with a preload is arranged on housing parts 46, 46' of the bearing of the spindle 2', wherein the preload corresponds to a reference value, e.g. the rated power of the motor of the drive unit or the impact force of the first stop element 35 on the second stop element 36.

[0071] When the first stop surface 30 (not shown in this figure) impacts the second stop surface 29, a temporary deformation of the housing parts 46, 46' or a change in the relative position of these components occurs, since the bearing bush 45 allows the first housing part 46 to be moved to a limited extent relative to the second housing part 46'. A sensor element 21 can detect this displacement or deformation, which represents a measure of the impact force, and transmit it to the braking device 38 via the transmission device 33.

[0072] Fig. Figure 10 shows a partially broken-away view of the machine room of an injection molding machine 34, a further embodiment of a detection device 11. In this case, the displacement of the sensor element 21 relative to the housing 47 of the machine room is detected and transmitted to the braking device 38 by means of the transmission device 33. The sensor element 21 can be preloaded by means of a spring 40, as in the previous figures, so that, due to the deformation of the components, in particular of the housing 47, during the impact, a relative positional displacement of the sensor element 21 relative to the housing 47 is detected and represents a measure of the impact force. In this figure, in addition to the ejector plate 9, the other components of the drive element 2 are arranged within the housing 48 of the ejector device. The stop plate 28 with the ejector pins 7 can be connected to the drive unit via the coupling piece 6.

[0073] A further detection device 11' with a further transmission device 33', for example in the form of a strain gauge, can be arranged on the outer wall of the housing.

[0074] Fig. 11 shows a further embodiment of a detection device 11 according to the invention, which has a vibration measuring device. A measuring plate 41 and a sensor element 21 are arranged on the ejector plate 9, the sensor element being at a preset distance from the measuring plate 41. As a result of the impact of the first stop element 35 on the second stop element 36, the measuring plate 41 is set into vibration, with the amplitude of the vibrations representing a measure of the impact force. The sensor element 21, which can be designed as an inductive sensor, measures the distance to the measuring plate 41. If this distance falls below a predetermined reference value as a result of the vibrations of the measuring plate 41, a signal is transmitted to the braking device 38 to initiate or intensify the braking process.

[0075] Fig. Figure 12a shows a schematic view of a clamping side of an injection molding machine 34, wherein a movable, mounted mold clamping plate 8 is translationally displaceable toward a stationary mold clamping plate 8' by an electric motor 13 via a front plate 49 and a spindle 2' by means of the toggle lever system 50. Instead of an electric motor, a hydraulic or pneumatic drive would also be conceivable. Upper and lower tie bars 51 are provided, among other things, to guide this movement, as well as to stabilize the injection molding machine and transmit the clamping force. A mold half 52, or 52', is arranged on both the movable mold clamping plate 8 and the stationary mold clamping plate 8'. Fig. 12a shows an open closing unit of the injection molding machine 34 based on the non-closed mold halves 52, 52', as well as the angled toggle lever system 50.

[0076] In Fig.12b, the clamping unit is closed so that the mold halves 52 and 52' are adjacent to one another. To ensure a fast production cycle, the clamping unit is closed very quickly, with the first mold half 52 impacting the second mold half 52'. An excessively hard impact can destroy the mold halves 52, 52', as well as the components connected to them. The first stop element 35 therefore encompasses the mold half 52 arranged on the movable mold clamping plate 8, while the second stop element 36 encompasses the mold half 52' arranged on the stationary mold clamping plate 8'.

[0077] The detection device 11 can be designed to measure the impact force of the mold half 52 on the mold half 52', as well as to measure the impact force of the first stop surface 30 on the second stop surface 30 in the case of the ejector device 1 as in the above examples. Furthermore, it is possible to use one and the same detection device 11 to detect both the impact force of the mold halves 52, 52' and the first stop surface 30 and the second stop surface 30. Therefore, the closing of the mold halves 52, 52' and the ejection of the injection-molded pieces can be controlled or monitored using a control device 31 according to the invention.

Claims

[1] Injection moulding machine with a first stop element moved by a drive unit, wherein the first stop element impacts a second stop element during the injection moulding process, and wherein a detection device (11) is provided, by which the force with which the first stop element (35) impacts the second stop element (36) can be measured and fed to a control device (31) via a transmission device (33), wherein the first stop element (35) comprises ejector pins (7) and a first stop surface (30) which can be moved, preferably in a translational manner, by the drive unit and are arranged for the ejection process on the part inserted in or on the injection moulding process.can be stopped on a second stop element (36) arranged on an injection mold; and / or that the first stop element (35) has a first stop surface (30) arranged on a movably mounted mold clamping plate (8), which can be stopped by the drive unit for the closing process on a fixed mold clamping plate (8') comprising the second stop element (36). characterized bythat the force with which the first stop element (35) impacts the second stop element (36) is comparable to a reference value by the control device (31), wherein a braking device (38) for decelerating the first stop element and / or a drive element (2) operatively connected to the first stop element (35) is controllable by the control device (31), wherein the deceleration by the braking device (38) is variable as a function of the difference between the force measured by the detection device (11) and the reference value. [2] Injection molding machine according to claim 1, characterized by that the braking device (38) can be controlled by the control device (31) to initiate or increase the deceleration of the first stop element (35) and / or the drive element (2) when the reference value is exceeded. [3] Injection molding machine according to one of claims 1 or 2, characterized bythat an emergency stop device, preferably in the form of a circuit breaker, is provided. [4] Injection molding machine according to one of claims 1 to 3, characterized by that the detection device (11) has a vibration measuring device and / or a deformation measuring device for measuring a vibration or deformation of the first stop element (35) and / or the second stop element (36) generated as a result of the impact of the first stop element (35) on the second stop element (36). [5] Injection molding machine according to one of claims 1 to 4, characterized by that the detection device (11) has a measuring device for measuring a damping force, preferably a spring force, which arises by the damping of the impact of the first stop element (35) on the second stop element (36). [6] Injection molding machine according to one of claims 1 to 5, characterized bythat an electronic memory is provided in which target curves (32) for the movement of the first stop element (35) are stored, wherein a calculation unit (37) is provided with which the target curves (32) can be modified and stored in the electronic memory by a calculation program stored in the calculation unit (37) as a function of the measured variable determined by the detection device (11). [7] Injection molding machine according to one of the preceding claims, with a drive element operatively connected to the first stop element and with a braking device for decelerating the first stop element and / or the drive element, wherein the drive unit comprises an electric motor (13), wherein the energy transmitted from the electric motor (13) to the drive unit can be reduced by the braking device (38). [8] Injection molding machine according to one of the preceding claims, with a drive element operatively connected to the first stop element and with a braking device for decelerating the first stop element and / or the drive element, wherein the braking device (38) comprises a hydraulic and / or pneumatic braking element. [9] Injection moulding machine according to claim 7 or 8, characterized by that the braking device (38) comprises a damping element. [10] Injection moulding machine according to claim 9, characterized by that the damping element is designed as a spring (4). [11] Injection molding machine according to one of the preceding claims, characterized by that the drive unit comprises a spindle drive with a spindle (2'). [12] Injection moulding machine according to one of the preceding claims, characterized bythat a sliding element (5) is provided for driving the first stop element (35), wherein the sliding element (5) is mounted so as to be movable in a limited translational manner relative to the drive element (2). [13] Injection moulding machine according to claim 12, characterized by that a guide element (3) connected to the drive element (2) is provided for the sliding element (5), wherein the sliding element (5) is mounted so as to be movable in translation relative to the guide element (3) to a limited extent and is guided by the guide element (3), and wherein a damping device, preferably a spring (4), is arranged in the guide element (3).

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