EP0365760A2 - Punching tool - Google Patents

Abstract

The invention relates to a tool which consists of a top and bottom tool for the punching, cutting and facultatively forming of workpieces. The semi-finished products for the workpieces are fed to the tool in the form of strip or flat material. The tool contains at least one device for recording measuring data specific to the workpiece as well as a device which serves to separate or mark those workpieces whose measuring data deviate from predetermined desired values. <IMAGE>

Description

The invention relates to a tool consisting of an upper and lower tool for punching, cutting and optionally forming workpieces, the semi-finished product of which is fed to the tool in the form of strip or flat material.

Workpieces that have to be punched, cut or formed during their manufacturing process are often machined in tools that are at least part of the press during the machining process. If the workpieces have a complicated shape, they have to do a lot of individual machining run through corridors. With such workpieces, a single special tool is required for each machining process. If the workpieces are small parts, the individual special tools are combined in a progressive tool. The special tools of the individual processing stages are arranged in chronological order of the processing operations in the progressive tool. Now the workpieces are divided by one feed length with each press stroke. A semi-finished product is thus fed to the first special tool of the progressive tool, while the finished special workpiece is ejected individually or hanging from the conveyor on the last special tool.

As a semi-finished product, mostly endless material (strip material) is used, from which the workpieces are worked out. During the process of working out, care is taken to ensure that the workpieces, depending on the degree of machining, are connected to a remaining, continuous ("endless") web via a more or less wide connection. In this way, the workpieces are lined up on an endless belt. This endless belt serves as a transport aid in and outside the tool.

Alignment on belts is particularly important for small parts that are to undergo surface finishing or other processing after mechanical processing. This applies, for example for small parts of the electrical industry (receptacles, cable lugs, flat plugs, solder pins, etc.) that have to be galvanically silvered or gold-plated. For this purpose, the endless belts are continuously passed through chemical baths.

In mechanical production, the semi-finished products in the form of a strip are thus formed into strips, which consist of continuous webs with workpieces attached to them. In order to check the manufacturing quality of the workpieces, workpieces were previously checked at the beginning and at the end of each band. The quality of the parts within the strip was deduced from the test result obtained. If it was later discovered during assembly that defective parts were between the measuring points, the entire batch, the workpieces of which had already been gold-plated or silver-plated, for example, had to be disposed of as rejects.

If obvious faults occurred during the mechanical processing, the tape was cut open and the rejects were removed. To do this, the press had to be shut down. Only after the band ends had been connected (welding, gluing, riveting, etc.) at the interface did the production process continue, although the connection point in the further automatic production process repeatedly led to faults.

Even if the quality check was carried out during the manufacturing process, the problem of cutting the tape to remove the rejects would remain. When measuring outside the tool, for example, there would also be the problem of synchronization between the press and the test device.

The invention is therefore based on the object of separating or marking the workpieces with measurement deviations in the tool without interrupting the production process, for which purpose the measurement data in the tool are first recorded as vibration-free as possible.

This object is achieved in that at least one device for recording workpiece-specific measurement data is arranged in the tool, that a unit for separating or marking the workpieces is connected downstream of this device in the feed direction and that this unit can be actuated if the measurement data deviate from a desired value . In particular, component measurements, material thicknesses, strength values (insertion and removal forces) and other measured variables are recorded during the manufacturing process. The measured variables can be tapped after individual processing steps or only on the finished part within the tool.

The measured values are compared with predefined tolerance values in an evaluation unit immediately after acquisition. If one or more measured values of a workpiece lie outside the manufacturing tolerance, then this workpiece is discarded or marked within the tool.

In order to create a good basis for the measurement, it is ensured that the measurement data acquisition can be carried out in the area of the movement reversal of the tool. This means that the release of the measured value acquisition takes place in the time range in which the direction of movement of the press slide, which carries the movable part of the tool, is reversed. This is the case at the bottom and top dead center of the press stroke. At these times, the slide or tool speed is zero.

The measurement data acquisition at the bottom dead center of the tool - that is, when the tool is closed - is particularly suitable for a low-interference measurement. The individual workpieces are clamped free of play between the upper and lower part of the tool. Even the aftershock of the press due to the inert masses of the moving parts has hardly any disturbing effects, since the sensors located in the upper and / or lower part of the tool cannot make any relative movements with respect to one another or against the workpieces at the time of the measured value acquisition. Precisely reproducible measurement results are the result of this inventive measure.

The measurement data acquisition takes place by means of light barriers according to the principle of light quantity measurement. For this purpose, the light barrier transmitter sends parallel light (infrared red light) to the receiver. The light beam has a cross section defined by an aperture. The receiver now measures the amount of light arriving at it. If a part of the light beam is covered by the workpiece to be measured, a length measurement value is calculated from the detected amount of light from the residual beam.

In the case of workpieces which have a clamping part (spring part), the holding force of the clamping part is detected by means of a clamping slide coupled to a pressure cell. For this purpose, a clamping slide is pushed between the clamping elements of the clamping part. After reaching its insertion depth, it is withdrawn. Sensors in or on the clamping slide detect the amount of insertion and / or holding force that is required for pushing in and pulling back.

In a further development of the invention, adjusting drives for adjusting at least one individual component of the tool are integrated in the tool and can be readjusted in a controlled manner by the measurement data deviation. This creates an opportunity to influence individual manufacturing steps. So z. B. bent tabs, e.g. B. locking devices, the different bending angles due to variations in sheet thickness have to be bent by additional tools moved by an electric motor. As adjustment drives can z. B. stepper motors can be used. Hydraulic and pneumatic drives are also conceivable.

The tool according to the invention is suitable both for the machining of individual workpieces and for the machining of workpieces which are connected via a remaining continuous web of the semi-finished product. If the workpieces belong to the latter group, it is particularly expedient to separate the workpieces with measurement deviations from the web by the downstream unit in the workpiece. Workpieces that are subject to measurement deviations also include workpieces that are missing parts. There are several advantages to the above process. On the one hand, all parts are checked during the manufacturing process (one hundred percent inspection) and each part with measuring deviations is punched off the web of the belt. The tool thus leaves a processed belt to which only quality-checked workpieces are attached. Secondly, the scrap is removed from the processing line without interrupting the chain or disrupting or even stopping the manufacturing process. However, the number of committee parts exceeds a predetermined limit, for. B. in a ghost shift, if the machine produces unattended, the machine is switched off.

Furthermore, the separated workpieces can be removed separately via a deflection device. This is conceivable if different quality levels are to be sorted out after the measurement. To do this, you can use a mechanical switch, for example, which sorts the parts into individual collecting containers.

Instead of discarding the workpieces with measurement deviations, these workpieces or the web in the vicinity of the web / workpiece connection can be marked by the unit. The marking can be a notch, a coloring or a color marking. The reject workpiece remains in the band. This has the advantage that the finished strip comes to rest when it is rolled up onto the transport roller.

A notch in the web is helpful for further processing of the tape, because if the workpieces are, for example, cable lugs to which cables have to be clamped by machine, the cable lugs remain on the web until after they are clamped on. If the web is now provided with a marking notch or a color spot, this means for the clip-on machine, which then queries such markings, that the defective part in the vicinity of the notch is left out.

Of course, workpieces that are not connected to one another by a continuous belt can also be machined and tested with the above-mentioned tools.

In summary, it can be concluded that the cost-effective production of stamped and bent parts is considerably improved by the inventive measures. These parts are now continuously manufactured in one tool, subjected to one hundred percent inspection and the low-quality parts removed from further processing outside the tool.

• Figur 1 Seitenansicht eines Werk­zeuges zum Stanzen, Schneiden, Um­formen und Messen
• Figur 2 Draufsicht auf das Unter­werkzeug aus Figur 1
• Figur 3 Ausschnitt aus der Meßein­richtung des Werkzeuges
• Figur 4 Blockschaltbild zu dem Aus­sonderungswerkzeug.

Further features and details of the invention result from the following description of the drawings:

• Figure 1 side view of a tool for punching, cutting, forming and measuring
• FIG. 2 top view of the lower tool from FIG. 1
• Figure 3 detail from the measuring device of the tool
• Figure 4 block diagram of the screening tool.

Figures 1 and 2 show a tool that is used to manufacture and simultaneously check the dimensions of small stamped and bent parts. The tool itself is part of a press. Continuous metal strips are fed into the tool as a semi-finished product. They are introduced into the workpiece from the left, to the left to the right to pass in strip guides. Each part in the tool passes through individual stations for cutting, punching, bending, measuring and sorting out individual scrap parts. Each of these stations, with the exception of the station for rejecting the committee parts, becomes active once with each working stroke. After each working stroke, the workpieces, which depend on a more or less wide web of the semi-finished product, depending on the degree of machining, are divided by one cycle.

The entire punching tool consists of an upper and lower tool 1 and 2.

Both tool parts have a base plate 5 and a head plate 4, on which the individual special tools 3 are built.

The base plate 5 and the top plate 4 are guided in parallel by precision ball guides, the guide columns 6 of which are shown in FIGS. 1 and 2. The tool shown in FIGS. 1 and 2 comprises four stations 10, 20, 30 and 40.

The station 10 is used for cutting or punching the semi-finished product. A cutting punch 11 and a hardened cutting bushing 12 form the core pieces of this assembly. For this purpose, the cutting plate 12 is inserted in a frame plate 13, which is mounted on a pressure plate 14. The three parts are rigid connected to the base plate 5. The cutting punch 11 is seated in a holding plate 15, which in turn is screwed to the top plate 4 via an upper pressure plate 16. In an intermediate plane between the frame plate 13 and the holding plate 15 there is a guide plate 17 which serves to hold down the workpiece during the punching process. It is guided via separate ball guides, the guide columns 9 of which are fastened in that of the guide plate 17.

The through hole 18 in the base plate 5, below the hardened cutting plate 12, serves to remove the cutout.

The assembly 20, which is connected downstream of the assembly 10 in the feed direction, is equipped with forming tools. With the bending punch 21 and 22 and their bending inserts 23 and 24, they accomplish two successive bending processes. For this purpose, the bending sets 23 and 24 sit in the frame plate 25, which is fastened to the base plate 5 via the pressure plate 26. The bending punches 21 and 22 are seated in the holding plate 27, which in turn are attached to the top plate 4 via the upper pressure plate 28. Here, too, a guide plate 29 helps to hold the formed workpieces down.

The assembly 30, which is arranged in the feed direction behind the assembly 20, is a measuring station. Two geometric dimensions can be detected in it with the help of light barriers. Thereby form the light barrier kenteile 31 and 32 the transmitter and the parts 33 and 34 the receiver of the light barrier. The transmitters sit in a carrier part 35 which is integrated in the receiving plate 36. The receiving plate 36 is fastened to the base plate 5 via the pressure plate 37. Compared to the transmitters, the receivers 33 and 34 are embedded in the carrier part 38, which is supported on the carrier part 35.

The measuring station 40 is followed by the measuring station and serves to separate out or separate the reject parts. The workpieces with measurement deviations are separated in this station from the continuous web that connects the individual workpieces with one another. A cutting device consisting of a cutting punch 41 and a cutting plate 42 is used for the separation process. The cutting plate 42 is screwed to the base plate 5 via the pressure plate 43. The cutting punch 41 is guided in the holding plate 44, which is fastened to the head plate 4 via the upper pressure plate 45. There is a recess in the holding plate 44, in which a wedge slide 48 is guided. This wedge carriage 48 is driven by a lifting magnet 47, specifically when a reject part is to be punched out. For this purpose, the wedge slide 48 (in FIGS. 1 and 4) is shifted to the left, as a result of which the cutting punch 41 is advanced in the direction of the cutting plate 42. The cutting punch 41 is now supported on the head plate 4 via the wedge slide 48 and the upper pressure plate 45 from. With this setting, the parts 41 and 42 come into engagement during a press stroke. The punched-out scrap parts leave the tool area via the bore 46 in the base plate 5. If a scrap part is followed by a good part, the lifting magnet 47 pulls the wedge carriage 48 back (for example by means of spring force), as a result of which a leaf spring 49 mounted in spring guides 49a pushes the cutting punch 41 upwards via a bolt 50 until the cutting punch 41 moves again supported on the alignment plate 45.

FIG. 2 shows a top view of the lower tool 2. In the rear part of the base plate 5 one can see the guide columns 6 of the precision ball guides. The lower parts of the assemblies 10, 20, 30 and 40 are located in front of these central guide elements. In the assemblies 10 and 20, the guide bores 7 with their ball cages 8 can be seen. In the assemblies 30 and 40, only the guide columns 9 are shown.

To guide the semi-finished product or the workpieces, the guide strips 91, 92, 93 and 94 are attached to all four assemblies.

FIG. 3 shows a measuring arrangement integrated in the workpiece for detecting workpiece-specific sizes using the example of a cable clamp 51. The cable clamps finished in the tool are firmly connected to a remaining web 52. This web is in the Provide the height of the cable clamps with index holes 53. The light barrier, consisting of a transmitter 54 and a receiver 55, recognizes the exact position of the processed endless belt within the tool. Only when the receiver 55 receives the prescribed amount of light from the light emitted by the transmitter 54, the next control process is released. The individual measuring processes are initiated by a marking on the 360 ° coding disk of the press.

Overall, the measuring stations 60, 70 and 80 are shown for this purpose. Geometric sizes are recorded directly in stations 60 and 70, while the insertion and removal force of the cable clamp is determined in measuring station 80. The station 60 has an x-shaped light barrier combination 62, 63, 64, 65, with which the opening angle of the rear crimea area 61 is determined. The rear crimp area comprises the sheathing of the wire after the wire has been attached.

In the measuring station 70, the height of a bent flap 71 is measured with the aid of a light barrier 72. The receiver of the light barrier is not shown. The tab 71 forms the barb with which the cable clamp is held in its insulating jacket.

The measuring station 80 serves to record the insertion and removal forces of the spring legs 81 and 82. For this purpose, a plug-in knife 83 is inserted between the spring legs 81 and 82. After reaching the insert deep the plug knife is withdrawn again. During the plug-in and pull-off movement, the sizes plug-in and pull-out forces are determined, which represent a measure of the holding force of the spring legs of the cable clamp.

In the present exemplary embodiment according to FIG. 3, all functionally essential measured values of each workpiece are thus detected at the cable clamp 51.

FIG. 4 shows the connection of the light barrier parts 31 - 34 with the lifting magnet 47. The receiver parts 33 and 34 pass on their received signals to measuring electronics 56, in which measured values are generated from the signals, which represent actual values. The actual values are fed to a comparator 57, to which a target value is predefined. If an actual value lies outside the specified target value, the solenoid 48 is actuated.

Claims (11)

1.Tool consisting of an upper and lower tool for punching, cutting and possibly forming workpieces, the semi-finished product of which is fed to the tool in the form of strip or flat material,
characterized,
that at least one device for recording (30 - 37, 54 - 83) workpiece-specific measurement data is arranged in the tool (1, 2, 3), that a unit for separating or marking (40 - 50) the workpieces is connected in the tool of this device in the feed direction and that this unit can be operated in the event of deviations in the measurement data from a desired value. 2. Tool according to claim 1,
characterized,
that the measurement data acquisition can be carried out in the area of movement reversal of the tool. 3. Tool according to claim 1,
characterized,
that the measurement data acquisition can be carried out in the area of the reversal of movement of the tool at the bottom dead center. 4. Tool according to claim 1,
characterized,
that the measurement data can be detected by means of light barriers (31-34) according to the principle of light quantity measurement. 5. Tool according to claim 1,
characterized,
that in the case of workpieces which have a clamping part (81, 82), the holding force of the clamping part can be determined by means of a clamping slide (83) coupled to a pressure cell. 6. Tool according to claim 1,
characterized,
that adjustment drives are integrated in the tool for adjusting at least one individual component of the tool, which can be readjusted in a controlled manner by the measurement data deviation. 7. Tool according to claim 1, wherein the workpieces are connected via a remaining, continuous web of the semifinished product,
characterized,
that the workpieces with measurement deviations can be separated from the web (52) by the downstream unit (40-50). 8. Tool according to claim 7,
characterized,
that the separated workpieces can be removed separately via a deflection device. 9. Tool according to claim 7,
characterized,
that the workpieces with measuring deviations or the web in the vicinity of the web / workpiece connection can be marked by the unit. 10. workpiece according to claim 9,
characterized,
that the mark is a notch. 11. Tool according to claim 9,
characterized,
that the marking is a coloring or color marking.

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