Press

Abstract

Press (10) comprising: a press stand (12); a slide (22) which is slidably mounted on the press stand (12) along a pressing direction (z) and can be locked at a desired height along the pressing direction (z) during a pressing operation on the press stand (12); a press ram (21) which is moved axially in the pressing direction (z) relative to the slide (22) during the pressing operation; and a position measuring device (62) which is configured to determine a first position of the slide (22) relative to the press stand (12) along the pressing direction (z) and a second position of the press ram (21) relative to the press stand (12) along the pressing direction (z).

Description

[0001] The present invention relates to a press which is preferably usable as a joining press.

[0002] Pressing and joining processes are an important part of modern assembly technology. A wide variety of well-established pressing systems are available for such applications. In addition to pneumatic and hydraulic pressing systems, so-called servo pressing systems (hereinafter referred to as "servo presses") are gaining increasing market share.

[0003] In servo presses, a variable-speed motor transmits torque, speed, and position information to mechanical components. These mechanical components within the drive train can, for example, be a rack and pinion drive or a screw drive (trapezoidal, ball, roller, or planetary roller screw drive). Here, the rotary motion of the drive (e.g., electric motor) is converted into a linear motion of the press ram. The motor torque determines the feed force (pressing force) of the press ram.

[0004] With presses of this type, it is often difficult to ensure that the press can be used for different workpiece sizes while still meeting the high precision requirements demanded of such presses. At first glance, it might seem obvious to provide a press with a comparatively long ram stroke to guarantee these properties. However, this is usually problematic due to space constraints. Furthermore, the precision requirements are hardly achievable with presses that have a relatively large ram stroke. For one thing, the mechanical guidance of the press ram becomes relatively difficult if it is comparatively long. The longer the press ram, the more difficult it becomes to absorb the lateral forces acting during the pressing process. Therefore, the ram stroke of such presses is usually only designed to be a few centimeters.

[0005] To accommodate different workpiece sizes, presses with a height-adjustable slide are typically used. This slide is mounted on the press frame so that it can be adjusted to the desired height depending on the workpiece size. The press ram, which is movably mounted on the slide, can then be adjusted together with the slide. Depending on the workpiece size, the slide is first adjusted to the desired height on the press frame and then locked in place. During the pressing process, the slide itself does not move; only the press ram moves relative to the slide. The slide itself remains locked to the press frame during the pressing process.

[0006] The slide adjustment thus allows even a press with a relatively short ram stroke to be easily adapted to different workpiece sizes. However, since the slide adjustment is typically done manually, it is difficult to achieve a precise height setting that meets the accuracy requirements of the respective pressing process.

[0007] It is therefore an object of the present invention to provide a press with which the aforementioned disadvantages can be eliminated or at least reduced to a minimum. In particular, it is an object to provide a press with which very precise pressing operations can be carried out, while at the same time being adaptable to different workpiece sizes and the press still occupies a comparatively small installation space.

[0008] This problem is solved according to the invention by a press which has the following components: a press stand; a slide which is slidably mounted on the press stand along a pressing direction and which can be locked at a desired height along the pressing direction during a pressing operation; a press ram which is coupled to the slide and is moved axially relative to the slide in the pressing direction during the pressing operation; and a position measuring device which is configured to determine a first position of the slide relative to the press stand along the pressing direction and a second position of the press ram relative to the press stand along the pressing direction.

[0009] The press according to the invention thus has a position measuring device that determines both the position of the slide (here referred to as the "first position") and the position of the press ram (here referred to as the "second position"). Therefore, during a pressing operation, both the position of the slide and the position of the press ram (each relative to the press frame) are continuously known. Accordingly, despite the adjustability of the slide to adapt to different workpiece sizes, it is possible to ensure extremely high precision, particularly with regard to the position of the press ram.

[0010] The second position, that is, the position of the press ram relative to the press frame, can be measured either directly or indirectly. Indirectly, this second position can be measured, for example, by detecting the position of the press ram relative to the slide, e.g., via a sensor attached to the slide or a measuring encoder integrated into the drive. Since the position of the slide relative to the press frame (first position) is also determined by the position measuring device, preferably directly, the position measuring device can thus also determine the second position (position of the press ram relative to the press frame) by appropriate addition.

[0011] According to a preferred embodiment, the position measuring device has a first sensor configured to measure the first position and a second sensor configured to measure the second position.

[0012] In this case, both the first and second positions are measured directly using separate, dedicated sensors. Both sensors measure a position along the same direction, namely the pressing direction. Preferably, both sensors measure along the same axis. Using two sensors to measure the slide and press ram positions significantly increases measurement accuracy. This improves process control and reduces the likelihood of errors during the pressing process.

[0013] According to a further embodiment, the first sensor and the second sensor are each designed as absolute encoders.

[0014] Unlike incremental encoders, absolute encoders do not require calibration of the two sensors. They enable precise and continuous position measurement, even after a power outage or a press restart. This contributes to the reliability and accuracy of the pressing process.

[0015] According to a further embodiment, the press stand has a dimensioning body, wherein the first sensor for measuring the first position interacts with the dimensioning body, and wherein the second sensor for measuring the second position interacts with the dimensioning body.

[0016] Both sensors therefore work together with the same physical dimension. A single physical dimension is thus sufficient for measuring the position of both the slide and the press ram. This not only saves space and costs, but also contributes to the accuracy of the positioning.

[0017] According to a further embodiment, the press stand has a first axial guide for guiding the slide on the press stand along the pressing direction and a second axial guide for guiding the press ram on the press stand along the pressing direction.

[0018] The separate axial guides for the slide and press ram ensure stable and precise guidance along the pressing direction. This minimizes deviations and ensures a consistent and extremely accurate pressing process. Furthermore, it significantly increases the rigidity of the overall system and, consequently, the accuracy of the press ram's positioning.

[0019] Of particular note is that, according to this design, the press ram is guided directly on the press frame. In conventional presses, the press ram is merely supported in the slide, which in turn is guided on the press frame. This additional guidance of the press ram on the press frame ensures a significant increase in stability and thus also in accuracy during a pressing operation.

[0020] Furthermore, the separate guidance of the press ram on the press stand simplifies the direct position detection of the press ram, since, for example, the second sensor can be integrated into the guide, interact with it, or be located adjacent to it.

[0021] According to a further embodiment, the press also has a drive mechanism for powering the press ram.

[0022] The drive enables automatic movement of the press ram, increasing the efficiency and automation of the pressing process. This reduces manual labor and increases process speed.

[0023] The drive preferably includes an electric motor.

[0024] According to a preferred embodiment, the drive is fixed to the slide.

[0025] Fixing the drive to the slide reduces mechanical complexity and potential misalignment of the press ram. This, in turn, simplifies the design and contributes to a stable and maintenance-friendly solution.

[0026] According to a further embodiment, the press also has a locking device which can be actuated between a locking state in which the slide is locked to the press frame and a release state in which the slide can be moved along the press frame along the pressing direction, and a manually actuated adjustment device for manually moving the slide along the press frame along the pressing direction as long as the locking device is in the release state.

[0027] The locking mechanism is preferably also manually operated. The ability to manually move and lock the slide allows for flexible adaptation of the press to different workpieces. This improves the user-friendliness and versatility of the press. Since the positions of the slide and the press ram are determined via the position measuring device, the highest precision requirements can still be met.

[0028] According to a further embodiment, the press also has a control device which is designed to compare the first position of the slide determined by the position measuring device with a workpiece-specific slide target position and to adjust the pressing process depending on this position comparison.

[0029] The control unit therefore enables automatic adjustment of the pressing process based on the position of the slide. This ensures greater precision and conformity of the final product, which simplifies quality assurance.

[0030] Such automatic adjustment of the pressing process based on the slide position is particularly advantageous in combination with a manually operated adjustment device. While a manually operated adjustment device allows for quick manual adjustment of the slide, it doesn't allow for absolutely precise manual adjustment. However, due to the automatic adjustment of the pressing process based on the slide position, it may be sufficient to position the slide only roughly, for example, within a target window of ± 0.5 mm, while still ensuring a positional accuracy of the press ram within, for example, 1 / 1000 mm.

[0031] According to one embodiment, the control device is designed to adjust a ram stroke of the press ram, in particular a stroke length of the ram stroke measured along the pressing direction, depending on the position comparison.

[0032] This ensures a very high positional accuracy with regard to the ram stroke, even if the slide position is not perfectly adapted to the workpiece.

[0033] According to a further embodiment, the press has a memory for storing a workpiece-specific slide target position for a large number of workpieces.

[0034] Saving workpiece-specific slide target positions enables quick and easy setup of the press for different workpieces, reducing setup times and increasing production efficiency.

[0035] For example, a press operator selects a workpiece to be processed via a corresponding operating terminal, and a corresponding target slide position has already been stored in the memory. This target slide position is then reported back to the operator, who can then manually adjust the slide to the corresponding target position. Alternatively, the control unit could also provide for automatic, motorized adjustment of the slide position to the target slide position stored in the memory.

[0036] According to a further embodiment, the press also features a user feedback device, which is designed to generate visual, auditory and / or haptic feedback depending on the position comparison.

[0037] This is particularly advantageous when combined with a manually operated adjustment device for moving the slide. For example, if an operator selects a workpiece, the control unit mentioned above can provide feedback on the corresponding workpiece-specific target slide position, to which the operator then adjusts the slide. During the slide's movement, the user receives corresponding feedback (visual, auditory, and / or haptic) based on a comparison between the slide's initial position determined by the position measuring device and the workpiece-specific target slide position. This facilitates the correct adjustment of the slide position to the target position for the press operator.

[0038] According to a further embodiment, the user feedback device can be configured to output a first feedback signal if a value of the position comparison is outside a specified tolerance range, and to output a second feedback signal, which differs from the first feedback signal, if the value of the position comparison is within the specified tolerance range.

[0039] For example, the user feedback device can include an indicator light that glows red while the slide position is outside the tolerance range and glows green when the slide position is within the tolerance range. This improves interaction with the operator and thus greatly simplifies the slide position adjustment for the operator.

[0040] Particularly in combination with the aforementioned configuration, in which the control unit adjusts the pressing process based on position comparison, it is perfectly sufficient for the operator to simply set the slide position within a tolerance range, for example, ± 0.5 mm around the target slide position. Setting the slide to the exact workpiece-specific target position is unnecessary and, for the reasons mentioned above, does not result in any loss of precision.

[0041] According to a further embodiment, the press stand has a force sensor which is designed to measure a pressing force exerted by the press ram on a workpiece to be machined.

[0042] The force sensor enables precise measurement of the pressing force exerted on the workpiece, improving quality control and increasing process reliability. This is particularly important for delicate, complex workpieces. Integrating the force sensor into the press frame allows for a space-saving design.

[0043] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0044] An embodiment of the invention is illustrated in the following drawings and is explained in more detail in the following description. The drawings show: Fig. 1 a perspective view of an embodiment of the press according to the invention; Fig. 2 a side view of the in Fig. 1 shown press; Fig. 3 a perspective view of the in Fig. 1 shown press without cladding; Fig. 4 a side view of the in Fig. 1 shown press without cladding; Fig. 5 a perspective view of a press stand of the in Fig. 1 shown press; Fig. 6 a perspective view of a slide including the drive of the in Fig. 1 shown press; Fig. 7 a sectional view of the in Fig. 6 shown slide including drive; Fig. 8 a perspective view of a press ram of the in Fig. 1 shown press; Fig. 9 a top view of the in Fig. 8 shown press ram; and Fig. 10 a sectional view of a stand base belonging to the press stand, which is shown in Fig. 1 shown press.

[0045] The Figuren 1-4 show an embodiment of a press according to the invention in perspective view and side view, wherein Fig. 3 und 4 The press is shown without its covering. The press is marked in its entirety with the reference number 10.

[0046] The press 10 has a press stand 12. The press stand 12 forms the basic structure of the press 10 and essentially serves as a support for the other components of the press 10. The press stand 12 is usually placed on a surface, e.g., a workbench.

[0047] The press stand 12 is designed in two parts. It has an approximately L-shaped base support 14 and a stand foot 16 attached to the base support 14. On the top of the stand foot 16 is a workpiece holder 18, designed here in a plate-like form, which serves to hold a workpiece to be pressed.

[0048] The workpiece holder 18 can be adjusted in the x and y directions for fine adjustment of the workpiece position using adjusting devices 20, which are designed here as adjusting wheels.

[0049] A so-called slide 22 is mounted on the press stand 12, more precisely on the base support 14 of the press stand 12, and is movable along the vertical direction (z-direction). This allows the operator of the press 10 to adjust the working height of the slide 22 to the size or height of the workpiece to be processed by the press 10.

[0050] The slide 22 is coupled to a press ram 21, which is moved axially in the z-direction relative to the slide 22 during a pressing operation. The z-direction thus corresponds to the pressing direction of the press 10. Depending on the application, various types of pressing tools can be attached to the lower end of the press ram 21, which come into direct contact with the workpiece during the pressing operation.

[0051] The slide 22 is guided in a guide groove 24, which is integrated into the base support 14, on the press frame 12. The height position or z-position of the slide 22 can be manually adjusted by means of an adjusting device 26 via a crank 28. The adjusting device includes a gearbox (not shown in detail here) that converts the rotary movement of the crank 28 into a linear movement of the slide 22 relative to the press frame 12.

[0052] Furthermore, a locking device 30 is provided, by means of which the slide 22 can be locked at the desired height on the press frame 12. While the slide 22 is locked to the press frame 12 in the locked position of the locking device 30, the slide 22 is movable in the z-direction on the press frame 12 when the locking device 30 is in the released position. It is therefore understood that the slide 22 can only be moved manually using the adjusting device 26 or the crank 28 as long as the locking device is in the released position.

[0053] Details of the locking device 30 are described in particular in Fig. 7 The locking device 30 is implemented as a type of eccentric clamp, which can be actuated via an eccentric clamping lever 32. The eccentric clamping lever 32 is connected to a threaded rod 34 which is attached to the slide 22 in a rotationally secured manner. The threaded rod 34 is visible through a recess 36 ( Fig. 5 ) through the base support 14 of the press stand 12. Simultaneously, the threaded rod 34 connects a clamping plate 38 to the eccentric clamping lever 32 via a pressure bolt 40. By actuating the eccentric clamping lever 32, the clamping plate 38 is pressed against the base support 14 of the press stand 12 via the pressure bolt 40, and the slide 22 is thus locked to the press stand 12.

[0054] A drive 42 for driving the press ram 21 is also attached to the slide 22. The drive 42 comprises an electric motor 44, which is preferably designed as a servo motor. Furthermore, the drive 42 comprises a spindle drive 46 coupled to the electric motor 44. The spindle drive 46 includes a threaded spindle 48 and a spindle nut 50 mounted on the threaded spindle 48.

[0055] The motor shaft 52 of the electric motor 44 is coupled to the threaded spindle 48 via a coupling 54 ( Fig. 7 The threaded spindle 48 is radially and axially supported on the slide 22 by means of an axial bearing 53. When the threaded spindle 48 is rotated by the electric motor 44, the anti-rotation spindle nut 50 performs a linear movement. This linear movement is transmitted to the press ram 21. For this purpose, the spindle nut 50 is rigidly connected to the press ram 21.

[0056] The press plunger 21 itself, which is particularly in Fig. 8 und 9 As can be seen, the press ram is constructed in several parts. The press ram 21 comprises two opposing side plates 56 and a ram housing 58 arranged between them, at the lower end of which is a tool holder 60 ( Fig. 2 and 4 ) is arranged to accommodate a pressing tool.

[0057] The press 10 also includes a position measuring device 62. This position measuring device 62 has both hardware and software components, which are only partially shown in the present drawings. Fig. 4 The position measuring device 62 is therefore shown schematically, with arrow 62 pointing towards a part of the device. The position measuring device 62 serves to determine the position of the slide 22 relative to the press frame 12 along the pressing direction (z-direction) and the position of the press ram 21 relative to the press frame 12 along the pressing direction (z-direction). The position of the slide 22 relative to the press frame 12 is referred to here as the "first position." The position of the press ram 21 relative to the press frame 12 is referred to here as the "second position."

[0058] The position measuring device 62 comprises a first sensor 64 ( Fig. 6 ) for measuring the first position, i.e. the position of the slider 22, as well as a second sensor 66 ( Fig. 9 ) for measuring the second position, i.e., the position of the press ram 21. Both sensors 64, 66 are preferably designed as absolute encoders. The position measuring device 62 is therefore preferably an absolute displacement measuring system. Accordingly, the height positions of the slide 22 as well as the height position of the press ram 21 can be determined at any time, even without a reference run or calibration.

[0059] Both sensors 64 and 66 interact with a measuring element 68, which is arranged on the press frame 12 along the pressing direction (z-direction). The wiring of the first sensor 64 is routed via a first energy chain 70, which connects the slide 22 to the press frame 12. The wiring of the second sensor 66 is routed via a second energy chain 72, which connects the press ram 21 to the press frame 12.

[0060] As can be seen particularly from the Figuren 3-5 As can be seen, both the slide 22 and the press ram 21 are guided separately on the press frame 12 along the z-direction, i.e., along the pressing direction. For this purpose, the press frame 12 has a first axial guide 74 for guiding the slide 22 and a second axial guide 76 for guiding the press ram 21. The first axial guide 74 includes the aforementioned guide groove 24. The second axial guide 76 comprises two guide rails 78, which are arranged on opposite sides of the press frame 12 ( Fig. 5 (shows one of the two guide rails 78). Two guide carriages 80 are guided on each of these guide rails 78, which are fixedly connected to the side plates 56 of the press ram 21.

[0061] The two axial guides 74, 76 ensure extremely stable and precise guidance of the press ram 21 and the slide 22. At the same time, the position measuring device 62 enables very precise position detection of the press ram 21 and the slide 22, preferably with an accuracy of up to 1 / 1000 mm.

[0062] The press 10 also features a user feedback device 82, which in the present embodiment includes a display 84. Furthermore, in Fig. 1 Only a control unit 86 and a memory 88 are schematically indicated. The control unit 86 and the memory 88 are shown here as integrated into the housing of the press 10. However, it is understood that the control unit 86 and the memory 88 can also be located externally and connected to the press 10 via a data connection (wired or wireless). Likewise, parts of the user feedback unit 82 or the entire user feedback unit 82 can be located outside the press housing. The control unit 86 is preferably an electronic control unit with a processor, which can be configured as a CPU, microprocessor, microcomputer, DSP, or the like. The memory 88 is, for example, a non-volatile or volatile semiconductor memory such as random-access memory (RAM), read-only memory (ROM), flash memory, or the like.

[0063] Memory 88 serves, among other things, to store a workpiece-specific target slide position for a large number of workpieces. In this way, corresponding target slide positions for a wide variety of workpieces can be predefined and saved, which the operator can then automatically recall by entering the workpiece. If the operator selects a specific workpiece to be processed by the press 10 using an operating terminal (not shown), the control unit 86 reads the corresponding target slide position from memory 88 and displays it to the operator, for example, on display 84. Display 84 also allows for the visualization of various states of the press 10 or the pressing result of the press 10. For example, the result of a pressing operation can be indicated by green (good) or red (bad).In addition to the target position of the slide, the actual position of the slide 22 (actual position of the slide 22) and the actual position of the press ram 21 (actual position of the press ram 21) can also be displayed on the display 84.

[0064] Typically, the position of the slide 22 cannot be adjusted with the same precision using the adjusting device 26 as with the actual position of the slide 22 measured using the position measuring device 62. However, if the height of the slide 22 is adjusted in conjunction with a workpiece change, it is sufficient if the slide 22 is located within a target window or tolerance range and is fixed there by the locking device 30. The operator can be supported during this adjustment process as follows. For example, a red light is displayed on the display 84 as long as the slide 22 is outside the tolerance range specific to the respective workpiece. As soon as the slide 22 is within the tolerance range, a green light is displayed on the display 84, indicating to the operator that the slide 22 is correctly positioned.

[0065] Due to the precise position detection by the position measuring device 62, the minor positional deviation within the tolerance range can be compensated for by the control device 86. The control device 86 is preferably configured to compare the initial position of the slide 22 determined by the position measuring device 62 with the workpiece-specific target position of the slide, which is stored in the memory 88, and to adjust the pressing process based on this position comparison. In particular, the control device 86 adjusts the stroke length of the ram stroke based on this position comparison. In this way, very precise pressing results can be achieved despite the manual adjustability of the slide 22.

[0066] Fig. 10 Figure 1 also shows a sectional view of the stand base 16. A force sensor 90 is integrated into the stand base 16, which can be used to determine the pressing force. The thermal and dynamic decoupling of the force sensor 90 from the drive train of the press 10 is advantageous for precise force measurement. Thermal influences caused by the heating from the electric motor 44 and vibrations of the threaded spindle 48 during positioning of the press ram 21 therefore have no significant influence on the measurement signal of the force sensor 90.

[0067] Above the force sensor 90 is the workpiece holder 18, which here is designed as a mounting plate. Customer-specific lower tools can be mounted on this mounting plate, which interact with corresponding upper tools mounted on the tool holder 60 of the press ram 21 during the pressing process. For the assembly of very small components, it is of utmost importance that the lower tool is precisely aligned with the upper tool. For this purpose, an xy-slide system is arranged in the column base 16, by means of which the mounting plate can be adjusted in the x- and y-directions. The adjustment is made using the adjusting device 20, which is located, among other places, in Fig. 1 and 10 as is evident.

[0068] Fig. 10 Figure 1 shows the adjustment device 20 for the x-direction in detail. As can be seen, an x-carriage plate 92 and a y-carriage plate 94 below it are integrated into the base 16. Each of these two carriage plates 92, 94 is equipped with a corresponding adjustment device 20, which serves for fine adjustment. The adjustment devices 20 are each based on a differential lead screw principle, which is constructed as follows. The fine adjustment has a setscrew 96, which is inserted into the respective carriage plate 92, 94. The setscrew 96 is connected to an adjustment knob 98, on which a threaded sleeve 100 is also mounted. The threaded sleeve 100 abuts a bearing plate 102. For example, a setscrew 96 with an M5 thread with a pitch of 0.8 mm is inserted into the x-carriage plate 92, which is secured against rotation in the direction of movement. The bearing plate 102 has the function of an axial stop for the threaded sleeve 100.The threaded sleeve 100, for example, has an internal M10 thread with a pitch of 1 mm. Furthermore, the threaded sleeve is secured against rotation. The adjusting knob 98, for example, has an internal M5 thread with a pitch of 0.8 mm and an external M10 thread with a pitch of 1 mm. The adjusting knob 98 is inserted both onto the threaded pin 96 with a pitch of 0.8 mm and into the threaded sleeve 100 via the M10 thread with a pitch of 1 mm.

[0069] When a full 360° rotation (360°) of the adjusting knob 98 is initiated clockwise, the adjusting knob 98 is moved 1 mm towards the bearing plate 102 due to the M10 thread. This rotation also affects the M5 threaded connection. Since the threaded pin 96 is fixedly connected to the x-slide plate 92, the latter is pulled 0.8 mm towards the bearing plate 102. Due to the different thread pitches, an effective stroke of the x-slide plate 92 of 0.2 mm is achieved per rotation of the adjusting knob 98. When the adjusting knob 98 is rotated clockwise, the distance between the x-slide plate 92 and the bearing plate 102 increases by 0.2 mm.

[0070] The effective stroke of the x-carriage plate 92 per revolution of the adjustment knob 98 can be determined by selecting the thread pitch. For example, if an external thread M10 with a pitch of 0.75 mm is selected in conjunction with a threaded stud M5 x 0.8 mm, an effective stroke of 0.05 mm would result per revolution of the adjustment knob. However, it should be noted that when the adjustment knob 98 is turned clockwise, the distance between the x-carriage plate 92 and the bearing plate 102 decreases.

[0071] It goes without saying that the same principle also applies to the adjustment of the y-slide plate 94.

[0072] This fine adjustment allows the lower tool to be set very precisely to the upper tool. Once the desired position is reached, it can be secured by tightening a threaded pin that blocks the rotation of the adjusting knob 98.

[0073] In Fig. 10 An overload protection device 104 is also provided for the force sensor 90. The force sensor 90 is a very sensitive component and must be protected against overload. An overload can occur, for example, due to faulty programming of the control unit 86. The press ram 21 could then drive the press tools to their limit at high speed. This would generate very high impulse forces for a short period of time, which could destroy the force sensor 90.

[0074] The overload protection device 104 integrated into the xy-slide system is designed to protect the force sensor 90 from such impulse forces. For this purpose, the x-slide plate is provided with a recess 106. Three cylindrical pins 108, 110 are inserted into this recess, with two of the cylindrical pins 108 having a smaller diameter than the third cylindrical pin 110. In this state, the cylindrical pins 108, 110 rest loosely on the y-slide plate 94. The cylindrical pin 110 with the larger diameter is positioned between the two cylindrical pins 108 with the smaller diameters. The right-hand cylindrical pin 108 with the smaller diameter is fixed in place by the end face of the recess in the x-slide plate 92. A threaded pin 112 is also inserted into the x-slide plate 92, arranged at a right angle to the cylindrical pins 108, 110.When the threaded pin 112 is moved by turning it in the direction of the cylindrical pins 108, 110, it comes into contact with the left cylindrical pin 108. By further adjusting the threaded pin 112, the middle cylindrical pin 110, with its larger diameter, lifts off the support surface of the y-slide plate 94 and is moved in the direction of the force sensor 90.

[0075] When the force sensor 90 is subjected to the intended maximum force of the press 10, the measuring diaphragm of the force sensor 90 deforms (maximum deformation). The central cylindrical pin 110, with a larger diameter, can then be advanced via the threaded pin until the measuring signal of the force sensor 90 changes. This indicates that the central cylindrical pin 110 on the force sensor 90, as described in Fig. 10The position of the threaded pin 112 is now fixed by tightening the threaded nut 114. If, in this state, a force higher than the intended maximum force is applied to the force sensor 90, it is absorbed by the central cylindrical pins 108 and 110. Thus, a very effective overload protection for the force sensor 90 is implemented.

Claims

1. Press (10) comprising: - a press stand (12); - a slide (22) which is slidably mounted on the press stand (12) along a pressing direction (z) and can be locked at a desired height along the pressing direction (z) during a pressing operation on the press stand (12); - a press ram (21) which is moved axially relative to the slide (22) in the pressing direction (z) during the pressing operation; and - a position measuring device (62) which is configured to determine a first position of the slide (22) relative to the press stand (12) along the pressing direction (z) and a second position of the press ram (21) relative to the press stand (12) along the pressing direction (z).

2. Press according to claim 1, wherein the position measuring device (62) comprises: - a first sensor (64) configured to measure the first position; and - a second sensor (66) configured to measure the second position.

3. Press according to claim 2, wherein the first sensor (64) and the second sensor (66) are each designed as absolute encoders.

4. Press according to claim 2 or 3, wherein the press stand (12) has a scale (68), wherein the first sensor (64) interacts with the scale (68) for measuring the first position, and wherein the second sensor (66) interacts with the scale (68) for measuring the second position.

5. Press according to one of the preceding claims, wherein the press stand (12) has a first axial guide (74) for guiding the slide (22) on the press stand (12) along the pressing direction (z) and a second axial guide (76) for guiding the press ram (21) on the press stand (12) along the pressing direction (z).

6. Press according to one of the preceding claims, further comprising a drive for driving the press ram (21).

7. Press according to claim 6, wherein the drive (42) is fixed to the slide (22).

8. Press according to one of the preceding claims, further comprising: - a locking device (30) which is actuable between a locking state in which the slide (22) is locked on the press stand (12) and a release state in which the slide (22) is displaceable on the press stand (12) along the pressing direction (z), and - a manually actuated adjustment device (26) for manually displacing the slide (22) on the press stand (12) along the pressing direction (z) as long as the locking device (30) is in the release state.

9. Press according to one of the preceding claims, further comprising a control device (86) which is configured to compare the first position of the slide (22) determined by the position measuring device (62) with a workpiece-specific slide target position and to adjust the pressing process depending on this position comparison.

10. Press according to claim 9, wherein the control device (86) is configured to adjust a ram stroke of the press ram (21), in particular a stroke length of the ram stroke measured along the pressing direction (z), depending on the position comparison.

11. Press according to claim 9 or 10, further comprising a memory (88) for storing a workpiece-specific slide target position for a plurality of workpieces.

12. Press according to one of claims 9-11, further comprising a user feedback device (82) which is configured to generate visual, auditory and / or haptic feedback depending on the position comparison.

13. Press according to claim 12, wherein the user feedback device (82) is configured to output a first feedback signal when a value of the position comparison is outside a predetermined tolerance range, and to output a second feedback signal, which differs from the first feedback signal, when the value of the position comparison is within the predetermined tolerance range.

14. Press according to one of the preceding claims, wherein the press stand (12) has a force sensor (90) which is configured to measure a pressing force exerted by the press ram (21) on a workpiece to be machined.

Images