EP1308268B1 - Automatic pressing or punching machine - Google Patents

Description

The invention relates to a press or punching machine with a frame which has a frame base with a clamping plate and a drive unit receiving frame upper part, which is supported by stands on the frame base, and with a drivable by the drive unit to a reciprocating ram, the via guide columns in the vertical direction slidably held on the frame, and with an adjusting device for adjusting the plunger reversing position during operation of the pressing or punching machine, the adjusting device is associated with a measuring device with a first, held on the movable plunger measuring element and a cooperating with this, held stationary second measuring member for contactless detection of the plunger reversing position, wherein the guide columns and the plunger and the clamping plate define a tool installation space for receiving tools wherein the first and the second measuring member au ßerhalb the tool installation space in a guide column encompassing area of the Stö-Bel are arranged.

In order to reduce tool wear in stamping or pressing machines and thus extend the service life of the tools, it is advantageous if the reversing position of the plunger, that is the bottom dead center, regardless of the temperature of the pressing or stamping machine and regardless of the particular in the acceleration phase occurring mass forces can be kept as constant as possible. For this purpose, in DE-OS 27 31 074 an actuator for proposed a ram position adjustment so that the StöBelumkehrposition can be adjusted during operation of the pressing or stamping machine. This makes it possible to keep the depth of immersion of an upper tool held on the plunger within the tool installation space in a lower tool fixed to the platen constant even as the number of strokes increases. DE-OS 27 31 074 suggests in this context, to arrange an inductive immersion depth measuring device within the tool installation space in the area of the tools, so that the immersion depth can be detected directly and passed on to a control device. By comparing the actual value and the set value of the immersion depth, the plunger reversal position can then be readjusted accordingly with the aid of the actuator.

Instead of a direct measurement of the immersion depth of the tappet, EP 0 367 035 B1 proposes an indirect measurement in which the pressure occurring in the tool is detected. For this purpose, a pressure transducer is used, which is held within the tool installation space on the upper tool or on the lower tool. The pressure acting on the pressure transducer when the upper tool and lower tool move together represents a measure of the immersion depth.

Another stamping or punching machine in which the plunger reversing position can be adjusted during operation is known from EP 0 732 194 B1. To measure the ram position, a measuring device is used with a first, with the plunger fixedly connected measuring element and a second, held stationary measuring element. The first measuring element is rod-shaped or band-shaped and has a recognizable by the second measuring element scale mark in the form of a plurality of alternating in the longitudinal direction of the first measuring element north and Südpolbereichen. The second measuring element comprises a detector head with an induction loop for providing a dependent of the relative position of the two measuring elements measuring signal. The two measuring elements are arranged at an inner corner region of the tool installation space.

If the measuring elements are installed in the tools, so that although the ram position can be detected very accurately, the conversion of the pressing or stamping machine is, however, connected due to the installation of the measuring elements with considerable retooling and adjustment work. If the measuring elements are arranged outside of the tools at an inner corner region of the tool installation space, then although the changeover times can be reduced, there is the risk of damage and contamination of the sensitive measuring elements.

An automatic press having the features of the preamble of claim 1 is known from Japanese Publication JP-A-2001062597. One of the measuring elements is held in this automatic press on the outside of the plunger.

Object of the present invention is to develop a pressing or stamping machine of the generic type such that in a structurally simple manner a reliable measurement variable for adjusting the plunger reversing position can be provided, which is practical there is no risk of damaging the measuring elements when retooling the tools.

This object is achieved in a pressing or stamping machine of the type mentioned in the present invention, that in each case a stand and / or a lateral protective wall are arranged at a distance from the guide columns and that the first and the second measuring element in the region between the guide column and the associated Stand or an associated protective wall are positioned.

As mentioned above, the plunger of the pressing or punching machine according to the invention by means of guide columns in the vertical direction is slidably held on the frame. For this purpose, the guide columns are encompassed by the plunger. The idea then flows into the invention of using the region of the tappet encompassing the guide columns to arrange the first and second measuring elements of the measuring device. In this area, the plunger extends beyond the tool installation space, so that the entire tool installation space is available for mounting tools and is not affected by the arrangement of the measuring elements. So it is the largest possible tool space available. If the tools are replaced, their assembly is not obstructed by the measuring elements, so that there is virtually no danger that the measuring elements will be damaged during the conversion of the press or stamping machine. The risk of contamination is significantly reduced.

According to the invention, a stand and / or a lateral protective wall are arranged at a distance from the guide columns, and the first and the second measuring element are positioned in the region between the guide column and the associated stand or the associated protective wall. The measuring elements are thus reliably protected against mechanical effects, since they are arranged outside of the tool installation space in the region between a guide column and the associated stand or the associated protective wall. In the direction of the tool installation space there is a protection due to the guide column, in the direction away from the tool installation space the measuring elements are covered by the stand or the protective wall.

It is advantageous if the pressing or stamping machine comprises an electronic comparison unit with the aid of which the measured variable provided by the measuring elements can be compared with a nominal value. The latter can preferably be predetermined via a programming unit of the comparison unit. The desired value can for example be specified by an operator after conversion of the pressing or stamping machine during a test run by the operator assessing the quality of the processed by means of the pressing or stamping machine workpiece. If the actual value determined by means of the measuring elements deviates from the predefinable setpoint value beyond a predetermined tolerance value, the plunger reversing position is correspondingly corrected. For this purpose, the known adjusting device is used, with the help of which the plunger position, in particular the bottom dead center of the plunger, can be readjusted during operation of the pressing or stamping machine.

Preferably, the second measuring element is held adjacent to the first measuring element on a stand. Alternatively, it could be provided to fix the second measuring element adjacent to the first measuring element on the press table.

In order to protect the second measuring element particularly reliable against mechanical effects, it is advantageous if the second measuring element is held on the side wall of the stator facing the associated guide column.

In a particularly preferred embodiment of the pressing or punching machine according to the invention it is provided that the pressing or punching machine comprises a strain gauge for measuring the elongation of the stator on which the second measuring element is held, and that the pressing or punching a strain gauge associated with the correction unit has to correct the of the measuring device provided measured value as a function of the measured signal of the strain gauge. Such a configuration has the advantage that measurement inaccuracies resulting from an elongation of the stator can be compensated. In order to detect the column elongation, the strain gauge is used, which provides a measuring signal for the correction of the measured value provided by the measuring unit. Consequently, during operation of the pressing or punching machine, the plunger reversing position can be determined very accurately, without it being necessary for this purpose to position the measuring elements within the tool installation space.

In order to be able to detect a non-uniform stator strain reliably, it is provided in a preferred embodiment that the pressing or punching machine has at least two Druckmeßglieder, which are arranged on two mutually diagonally opposite uprights of the frame. The diagonal arrangement of the pressure on the frame makes it possible in a structurally simple way to determine unevenmä-ßige stator strains, so that measurement inaccuracies with respect to the bottom dead center of the plunger can be corrected due to a non-uniform stator elongation.

A particularly high degree of precision in the measurement of the ram reversal position with unaffected by the measurement tool installation space can be achieved in that the pressing or stamping machine comprises at least two measuring devices each having a first and a second measuring element, the measuring devices outside of the tool installation space in diagonally opposite, in each case a guide column encompassing areas of the plunger are arranged. The diagonal arrangement of the measuring devices makes it possible compensate possibly occurring Führungsunsymmetrien the plunger, so that despite the measurement of the plunger position outside the tool installation space reliably the position of the plunger can be determined within the tool installation space.

It is of particular advantage in this case if the pressing or stamping machine comprises a signal processing unit which is connected to the calculation of an average value of the measuring signals provided by the two measuring devices with the two measuring devices. The averaging of the two measured signals recorded in a diagonal arrangement makes it possible, in a structurally particularly simple way, to determine the ram position prevailing inside the tool installation space.

For non-contact detection of the plunger position, the first and second measuring elements, for example, interact magnetically. Thus, the second measuring element, for example, a magnetic field-sensitive sensor, preferably a Hall sensor, wherein the magnetic field strength prevailing at the sensor is dependent on the position of the first measuring element. For this purpose, the first measuring element can have a control element for influencing the magnetic field prevailing at the location of the sensor. The control member may be configured conical, for example, so that changed by a vertical movement of the first measuring element, the distance of the control member to the sensor of the second measuring element and thereby the magnetic field strength occurring at the sensor is affected.

In a preferred embodiment of the pressing or punching machine according to the invention it is provided that the first and the second measuring element cooperate inductively. Here it is particularly favorable when the first or the second measuring element engages in the respective other measuring element. Preferably, one of the two measuring elements comprises a coil through which a current dependent on the position of the other measuring element flows. For example, one of the two measuring elements can have a multiplicity of north and south poles arranged in series with one another and alternating one another. Preferably, the row of north and south poles is arranged on the first measuring element, which for this purpose has a rod-shaped or band-shaped configuration. The second measuring element preferably has a U-shaped groove in which the first measuring element dips, and comprises at least one induction coil, so that a relative displacement of the two measuring elements within the induction coil induces a current which can be detected by an associated detector to provide a from the position of the plunger dependent measurement signal.

Figur 1:

eine schematische Darstellung eines Preß- oder Stanzautomaten und

Figur 2:

eine Schnittansicht längs der Linie 2-2 in Figur 1.

The following description of a preferred embodiment of the invention serves in conjunction with the drawings for further explanation. Show it:

FIG. 1:

a schematic representation of a pressing or stamping machine and

FIG. 2:

a sectional view taken along the line 2-2 in Figure 1.

As an example of a pressing or punching machine according to the invention, a high-speed punching machine is shown schematically in the drawing, which is generally occupied by the reference numeral 10. It comprises a frame-like frame 12 with a frame base 14 and a Gestelloberteil 15, extending over a total of four, in the corners a rectangle arranged stand 16 on the frame base 15 is supported. The stand 16 thus have a supporting function and are designed accordingly solid.

The frame upper part 15 receives a drive unit 18 for driving a reciprocating in the vertical direction plunger 20. For this purpose, the drive unit comprises an eccentric shaft 22 which is rotatably supported by roller bearings 24 on the frame 12 and by means of a not shown in the drawing, in itself known drive motor can be driven to a rotary motion. On the eccentric shaft 22, two connecting rods 26, 27 are rotatably supported. Both connecting rods 26 and 27 are held with their free end via a provided for adjusting the reversing position of the plunger adjusting device 29 on the plunger 20.

The guide of the plunger in the vertical direction by means of a total of four arranged in the corners of a rectangle guide columns 31 to 34, which are each surrounded by a support arm 35, 36, 37 and 38 of the plunger 20, so that the guide columns 31 to 34 - respectively a stand 16 adjacent - are held immovably on the plunger 20.

The guide columns 31 to 34 are aligned vertically with their respective longitudinal axis 31a to 34a and delimit in the horizontal direction a tool installation space 40 whose vertical extension is limited by the underside of the plunger 20 and the upper side of a clamping plate 42 of the frame base 14. Within the tool installation space 40 can be on the plunger 20 and the platen 42 is a known per se and therefore not shown in the drawing lower tool or in the drawing also not shown, Mount a known upper tool for punching or pressing a workpiece.

Each guide column 31 to 34 is above and below the tool installation space 40 a play biased roller bearing 45 associated with a guide bush, so that the plunger 20 by means of the guide columns 31 to 34 and the rolling bearing 45 is guided in the vertical direction exactly.

In order to minimize the effects of temperature occurring in continuous operation of the high-speed stamping machine, an oil cooling circuit 47 is provided with an oil tank, not shown in the drawing, which is integrated in the frame base 14.

The plunger 20 is driven via the connecting rods 26 and 27 by means of the eccentric shaft 22 to a reciprocating motion. To compensate for the mass forces occurring in this case, the drive unit 18 comprises a arranged above the eccentric shaft 22 and coupled thereto via a connecting rod 49 balancing mass 51, which is guided on vertically oriented guide rods 53.

The installation of the high-speed stamping machine 10 on a bottom surface 55 via vibration damper 57, which allow the most environmentally friendly installation of the high-speed stamping machine 10 by occurring vibrations are very strongly damped.

During the start-up phase of the high-speed stamping machine 10, despite the use of the cooling circuit 47, a slight increase in temperature can not be avoided. This temperature increase leads as well as occurring inertial forces to the fact that the lower reversal point of the plunger 20 changes slightly. To counteract this change, the plunger reversing position of the plunger 20 can be adjusted during operation of the pressing or stamping machine 10 by means of the adjusting devices 29. To determine the plunger position, a measuring device 60 or 62 is respectively arranged in the region of the guide column 31 and in the region of the guide column 31 diagonally opposite guide column, each one first, outside of the tool installation space 40 in the region of the respective support arm 35 and 38 fixed first Measuring member 64 and a cooperating with the first measuring element 34, held on each adjacent stator 16 held second measuring element 66 include. The horizontal extent of the tool installation space 40 is, as explained above, determined by the guide columns 31 to 34. As is particularly clear from Figure 2, the two measuring devices 60 and 62 are arranged outside of the tool installation space 40, because the respective one guide column 31 to 34 embracing support arms 35 to 38 protrude beyond the tool installation space 40, and the first measuring members 64 are in the above fixed to the tool installation space 40 projecting area on the holding arms 35 and 38 respectively. The second measuring members 66 are, also outside the tool installation space 40, fixed to the respective adjacent stand 16.

The first measuring members 64 are each configured bar-shaped and have a plurality of longitudinally one behind the other arranged north and south poles. The second measuring elements 66 each comprise a receiving groove into which the first measuring elements 64 dive, and in each case an induction coil (not shown), in which during displacement of the plunger 20 and the associated relative movement of the first measuring elements 64 an induced current is induced. Such measuring devices 60 and 62 with first and second measuring members 64 and 66 are known per se and described for example in EP 0 732 194 B1. The two measuring devices 60 and 62 are connected via electrical lines, not shown, with a signal processing unit 71 in electrical connection, which in turn is coupled via not shown electrical lines with the adjusting devices 29. The signal processing unit 71 comprises an electronic display device 73 and a keypad 74 for inputting control data and is used to control the high-speed stamping machine 10 including the adjusting means 29. In addition, the signal processing unit 71 controls a known per se, not shown in the drawing feed apparatus, with the Tool installation space 40 to be machined workpieces can be supplied.

As can be seen in particular from FIG. 2, the two measuring devices 60 and 62 are arranged outside the tool installation space 40, specifically in a region between the respective guide column 31 and 34 and a lateral protective wall 68 fixed to the respectively assigned stand 16, so that the measuring devices 60 and 62 are protected on the one hand by the respective guide column 31 and 34 and on the other hand by the respectively associated stand 16 and the protective wall 68 against mechanical effects.

By means of the first and second measuring members 64 and 66 of the two measuring devices 60 and 62, the position of the bottom dead center of the plunger 20 can be detected during the ongoing operation of the high-speed stamping machine 10. The two measuring devices 60 and 62 provide the signal processing unit 71 each a measurement signal, the signal processing unit 71 forms an average, which is used to control the adjustment 29.

The second measuring members 66 of the two measuring devices 60 and 62 are held on the respective guide column 31 and 34 facing side wall 76 of the respectively adjacent stand 16. The respective side wall 76 additionally receives in each case a strain gauge 78 or 80, for example, a strain gauge, with the aid of a temperature-induced strain of the respective stator 16 can be detected. The strain gauges 78 and 80 are also electrically connected to the signal processing unit 71 via electrical leads not shown in the drawing. The measurement signals of the strain gauges 78 and 80 are used to correct the measurement signals provided by the measuring devices 60 and 62. For this purpose, the signal processing unit 71 comprises a correction unit 82, so that occurring due to a stator strain measuring inaccuracies of the measuring devices 60 and 62 can be compensated.

If, during operation of the high-speed stamping machine 10, a change in the bottom dead center of the plunger 20 occurs, this is registered by the measuring devices 60 and 62, which provide an ACTUAL signal which can be compared with a desired signal predeterminable by the signal processing unit 71. If the deviation determined in this case exceeds a tolerance range which can likewise be predetermined by the signal processing unit 71, the adjusting devices 29 are activated to correct the plunger reversing position by readjusting the effective length of the connecting rods 26 and 27.

Claims (11)

1. An automatic pressing or punching machine (10) with a frame (12) having a frame lower part (14) with a clamping plate (42) and a frame upper part (15) which receives a drive unit (18) and is supported on the frame lower part (14) by uprights (16), and with a ram (20) which is drivable by the drive unit (18) to produce a reciprocating movement and which is held on the frame (12) so as to be vertically displaceable via guide pillars (31, 32, 33, 34), and with an adjusting device (29) for adjusting the ram reversal position during operation of the automatic pressing or punching machine (10), wherein the adjusting device (29) is associated with a measuring device (60; 62) with a first measuring element (64) held on the movable ram (20), and a fixedly held second measuring element (66) co-operating with the first measuring element (64) for contactless detection of the ram reversal position, wherein the guide pillars (31, 32, 33, 34) together with the ram (20) and the clamping plate (42) define a tool installation space (40) for the accommodation of tools, and wherein the first and the second measuring element (64, 66) are arranged outside the tool installation space (40) in a region (35, 38) of the ram (20) engaging round a guide pillar (31, 34), characterised in that a respective upright (16) and/or lateral protective wall (68) are arranged with spacing from the guide pillars (31, 32, 33, 34), and in that the first and the second measuring element (64, 66) are positioned in the region between the guide pillar (31, 32, 33, 34) and the associated upright (16) or an associated protective wall (38).
2. An automatic pressing or punching machine according to claim 1, characterised in that the second measuring element (66) is held on an upright (16) so as to be adjacent to the first measuring element (64).
3. An automatic pressing or punching machine according to claim 2, characterised in that the second measuring element (66) is held on the side (76) of the upright (16) facing the adjacent guide pillar (31, 34).
4. An automatic pressing or punching machine according to claim 2 or 3, characterised in that the automatic pressing or punching machine (10) comprises a strain measuring element (78) for measuring the strain of the upright (16) on which the second measuring element (66) is held, and in that the automatic pressing or punching machine (10) has a correction unit (82) which is associated with the strain measuring element (78) and is provided for correcting the measured value provided by the measuring unit (60, 62) as a function of the measuring signal from the strain measuring element (78).
5. An automatic pressing or punching machine according to claim 4, characterised in that the automatic pressing or punching machine (10) comprises at least two strain measuring elements (78) arranged on two diagonally opposing uprights (16) of the frame (12).
6. An automatic pressing or punching machine according to any one of the preceding claims, characterised in that the automatic pressing or punching machine (10) comprises at least two measuring devices (60, 62) each having a first and a second measuring element (64, 66), wherein the measuring devices (60, 62) are arranged outside the tool installation space (40) in diagonally opposing regions (35, 38) of the ram (20), the regions (35, 38) engaging round a respective guide pillar (31, 34).
7. An automatic pressing or punching machine according to claim 6, characterised in that the automatic pressing or punching machine (10) comprises a signal processing unit (71) which is connected to the two measuring devices (60, 62) in order to calculate an average value of the measuring signals provided by the two measuring devices (60, 62).
8. An automatic pressing or punching machine according to any one of the preceding claims, characterised in that the first and the second measuring element (64, 66) co-operate with one another magnetically.
9. An automatic pressing or punching machine according to any one of the preceding claims, characterised in that the first and the second measuring element (64, 66) co-operate with one another inductively.
10. An automatic pressing or punching machine according to claim 8 or 9, characterised in that one of the two measuring elements (66) comprises a coil, and through the coil flows a current which is dependent upon the relative position of the two measuring elements (64, 66).
11. An automatic pressing or punching machine according to claim 10, characterised in that one of the two measuring elements (64) has a plurality of alternating magnetic north- and south-pole regions arranged in a row one behind the other.

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