JPH07195133A - Method and device for joining thin plates - Google Patents

Abstract

PURPOSE: To detect faults, which may happen in a large area, by measuring a pressing force, which is either given to a plate as a punching force by a punch or as a dieing force by a die, at least at one point where either dieing or punching is given which is prescribed in a working procedure. CONSTITUTION: A die accepter 4 for a die 5 is located at a press table 3, and a punch holder 7 for accepting punch 8 is located at an upper bracket 6 of a frame 2, facing to the die accepter 4. The punch 8 is vertically driven by an electric-powered press driver 11 mounted on an upper position of the frame 2 through a pressure cylinder 10. A piezoelectric power sensor is provided in the die accepter 4 with which a force applied to the die 5 is measured. A piezoelectric sideway dowel is provided in the holder 7 for measuring a punching force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold joining method for joining thin plates or plate parts arranged one above the other, wherein the plates or plate parts to be joined are located one above the other. The surface portion is deep-drawn together in a single working step by the co-operation of the punch and die, and then the surface portion is partially punched, or without this punching,
The present invention relates to an apparatus for carrying out a method performed by squeezing and spreading.

[0002]

2. Description of the Related Art A known cold joining method (D
E3532899), plate members stacked one above the other are stamped out along the contour lines of these plate parts and extruded from the plate plane in the same working step. The extruded plate member is then squeezed out by the opposing force. At this time, a punching protrusion is formed, and this protrusion engages with (hangs on) the plate portion to be joined. In another known method of this type (DE3532900), the plate members are commonly punched from the plate parts to be joined, at which time the plate parts are compressed based on the shape of the die. A rear extrusion process takes place in which the plate members engage from behind the plate parts arranged one above the other.

Such a method is used in industrial mass production, for example in automobile manufacturing. Therefore, monitoring the quality of such joints, or meeting certain quality requirements for such joints is
It is particularly important in such a method. If a defect occurs when carrying out such a method, this defect must be detected as early as possible and removed in order to reduce defective products as much as possible and machine stop time as short as possible. I won't. Such defects are caused by breakage of the material, especially the punch or die. In this case, it is important to detect the respective defective joints in order to be able to select the corresponding parts or to repeat the joining process. The criterion for the quality of the bond and the bond defect in this case is the thickness of the remaining material remaining in the area of the bond. In the known method, quality assurance is achieved by monitoring the punch force associated with the maximum value allowed and measuring the thickness of the remaining material after the joining operation. However, this makes it possible to detect only part of the defects as much as possible. Moreover, subsequent measurement of the remaining material thickness is tedious and time consuming.

[0004]

The object of the present invention is therefore to eliminate the drawbacks of the prior art.

[0005]

According to the method of the present invention which has solved this problem, the pressing force applied by the punch to the plate as a punch force or the pressing force applied by the die as a die force to the plate is determined by a predetermined working process. Given by the
The measurement was made at at least one point between the die and the punch.

According to the apparatus for carrying out the method of the present invention, a die arranged in a mechanical press and a punch reciprocating laterally with respect to the plates to be joined. And is provided with a position indicator and at least one force measuring device.

[0007]

The method and device according to the invention have the advantage that defects occurring in large areas can be detected and that the remaining material thickness does not have to be measured separately. The pressing force, i.e. the punch force or the die force, is in the form of a measuring curve representing the pressing force for the working stroke and does not have to be detected during the whole joining process. By measuring the pressing force during a given working stroke, the respective defective joint is detected. The monitoring is done by comparing against a predetermined maximum and minimum value. When the pressing force is below a predetermined maximum value, for example, punch breaks and die breaks are displayed, and when the pressing force exceeds a predetermined maximum value, this is because the plates are too thick or the plates to be joined are to be joined. Indicates that the material is too stiff.

According to another advantageous method of the invention, in addition to the plate force, the strip force required to remove (strip) the plates to be joined from the punch is measured. By measuring this strip force, the lining of the material is defined. This is especially important when the invention is used in robotic devices.

According to another method of the present invention, the pressing force is measured immediately after the end of the squeezing process. The actual joining process is completed because the plates joined by the joining process only have the remaining bottom thickness defined for the joining process at the joining location. Therefore, the pressing force corresponding to the working process concerned is particularly effective for the joining process.

According to another method of the present invention, the pressing force and / or the removing force are compared with a predetermined maximum value and a predetermined minimum value. If the measured value is within the interval defined by the maximum and minimum values, the formed bond corresponds to a given quality, whereas if the measured value is outside the interval, the bond is It has a defect. Therefore, comparing the measured values to the intervals is sufficient to characterize the bond.

According to another method of the invention, a signal is generated when a predetermined maximum value given for the monitored force is exceeded and when this predetermined minimum value is exceeded. . This signal is used to control an optical and / or acoustic display device to indicate the presence of a defect. This signal is also used to control the interruption of the bonding process, which reduces defectives and production downtime.

According to another method of the present invention, a signal is generated when the punch and the die do not perform a predetermined work process during the bonding process. This signal is preferably a control signal for controlling the optical and / or acoustic display device. This signal is also used to interrupt the bonding process.

According to another method of the invention, the maximum and minimum values are stored in an electronic memory in a callable manner. This allows the values to be adapted to each need. Multiple combinations of values can be stored in memory so that they can be quickly calculated for different requirements, for example tool changes or material changes.

According to another method of the present invention, a predetermined work process is stored in an electric memory in a callable manner. In addition to the possibility of carrying out the work process manually, for example by means of a switch, this also allows the work process to be adjusted via a computer with a memory.

According to yet another method of the invention, the value input is protected against retrieval or loss. This allows only authorized people to make changes.

According to another method of the present invention, the forces at a large number of cold joints are simultaneously measured and evaluated by a common evaluation device.

According to another method of the invention, the detected measurement value is optically displayed. The optical display is
This facilitates the distinction between different defect types so that suitable counter measures can be taken. For this reason, the detected measurements can be stored in memory in order to allow later evaluation. At the same time, storing the measured values by being able to re-examine later when the joining process is questioned
Useful for quality control.

An apparatus for carrying out the method of the invention is described in claim 19. According to this device of the invention, the force measurement is provided in a die receiving part or a punch holder or a stripper (for removing the press material from the punch), preferably an extension measuring strip or a piezoelectric sensor, for example a die receiving part. There is provided a piezoelectric power sensor provided on the section, a piezoelectric lateral measuring dowel provided on the punch holder, and a piezoelectric measuring ring provided on the stripper. The position indicator ensures that the measurements are accurate in the pre-adjusted work process. Advantageously, the position indicator is received in the punch stroke limiter.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The press 1 shown in FIG. 1 has a C-shaped frame 2, the lower part of which is used as a press table 3. A die receiving portion 4 for a die 5 is arranged on the press table 3. The upper bracket 6 of the frame 2 is provided with a punch holder 7 arranged to face the die receiving portion 4 and for receiving the punch 8. A stripper 9 is arranged around the punch holder 8 to remove the plate caught on the punch. The punch 8 is vertically moved by a press transmission device 11 provided on the upper side of the C-shaped frame 2 via a pressure cylinder 10.

A piezoelectric power sensor is provided in the die receiving portion 4, and the force applied to the die is measured by this power sensor. Within the punch holder 7 there is provided a piezoelectric lateral measuring dowel for detecting the applied punch force. Further, the stripper 9 is provided with a piezoelectric measuring ring 13 arranged so as to surround the pressure cylinder 10. Pressure cylinder 1
0 has a position indicator 14 and this position indicator 14
Activates a force measuring device in a given punch stroke to measure the force of the punch and possibly the force of the die. The position indicator is also received within the punch stroke limiter 15. The evaluation device and the electrical connection between the evaluation device and the measuring device are not shown.

The diagram shown in FIG. 2 is a graph showing an example of the relationship between the punch stroke and the punch force during the welding process. As shown in this diagram, the punch force does not always rise until the end of the welding process, but depends on the welding process. The different joining processes follow the sequence of joining operations, firstly descending, biting, compressing and rolling, then filling the upper contour of the die embossing, filling the annular passage of the die and then the plate to be joined. A blank rear cold extrusion is performed to assemble the parts together. The punch force is measured by the force-measuring device at the value of the adjustment stroke indicated by the symbol I in the diagram of FIG. This measured value is designated by the symbol II.
The interval V is defined by the minimum value III and the maximum value IV. If the measured value II is within the interval V, the filling process obtained corresponds to a predetermined quality. On the other hand, if the measured value VI exceeds the predetermined maximum value IV, the filling is defective. This may be because the sheet metal is too thick, has too many layers, is too strong, or has a wrong combination of tools. Also, another possibility of incorrect joining is indicated by point VIII. Here, the position indicator fails to activate the force measuring device. This is because the punch has not advanced the predetermined punch stroke. The reason may be that the adjusted plate force is too small, the plate stroke is not complete, or the bottom thickness of the unpressed portion at the joint is not reached.

The method according to the invention can be used in presses involving reciprocating punch movements, as well as methods involving rotary movements of the punches. In this case, instead of reciprocating movement, rotational movement is detected by a rotation angle sensor. In order to maintain the target value within the tolerance range, in addition to measuring the force, the acceleration is also measured, for example by measuring the vibration noise produced during the stroke movement. If the acceleration is too high, there is a strong material friction and thus the risk of breaking the tool.

[Brief description of drawings]

FIG. 1 is a partially cutaway schematic side view of an apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between punch force (vertical axis) and punch stroke (horizontal axis).

[Explanation of symbols]

1 press, 2 frame, 3 press table,
4 die receiving part, 5 die, 6 bracket, 7
Punch holder, 8 punch, 9 stripper,
10 pressure cylinder, 11 press transmission device, 12 lateral pressure measuring dowel, 13 piezoelectric measuring ring, 14 position indicator, 15 punch stroke limiter, I predetermined punch path, II, VI, VII possible measured values, III minimum value, IV maximum value, V interval

Claims (26)

[Claims] 1. A method for joining thin plates or plate portions arranged above and below each other by a cold joining method, wherein the surface portions of the plates or plate portions to be joined which are located above and below each other are provided once. In the working process,
Deep drawing together by the cooperating work of the punch (8) and the die (5) and then partially punching out said surface part, or squeezing and spreading without this punching Measuring the pressing force that the punch applies to the plate as a punch force or the pressing force that the die applies to the plate as a die force at at least one point between the die and the punch, which is given by a predetermined work process. For joining thin plates. 2. The method according to claim 1, wherein, in addition to the plate force, the removal force required to remove the plate or plate parts to be joined from the punch is also measured. 3. The method according to claim 1, wherein the pressing force is measured immediately after the end of the squeezing step. 4. The method according to claim 1, wherein the pressing force and / or the removing force is compared with a predetermined maximum value and a predetermined minimum value. 5. The method according to claim 4, wherein a signal is generated above a predetermined maximum value given for the monitored force and below this predetermined minimum value. . 6. A signal is generated when the punch and the die do not perform a predetermined work process during the joining process.
Method according to any one of claims 1 to 5. 7. The method according to claim 1, wherein the signal is a control signal for controlling an optical and / or acoustic display device. 8. The method according to claim 5, wherein the signal is used to control the interruption of the corresponding joining process. 9. The method according to claim 8, wherein the method can be continued after the interruption after the cancellation. 10. The method according to claim 1, wherein the maximum value and the minimum value are stored in an electronic memory in a callable manner. 11. The method according to claim 10, wherein the maximum and minimum values in the force measuring device are adjustable manually or via a computer stored in memory. 12. The method according to claim 10, wherein the memory stores a large number of combinations of maximum and minimum values. 13. A method according to claim 1, wherein the predetermined work steps are stored in an electronic memory in a callable manner. 14. The method according to claim 13, wherein the predetermined working process is adjustable manually with a position indicator or via a computer with a memory. 15. Protecting maximum and minimum values and / or work process inputs against removal or loss,
The method according to any one of claims 10 to 14. 16. The force at a large number of cold joints is simultaneously measured and evaluated by a common evaluation device.
16. The method according to any one of 1 to 15. 17. The method according to claim 1, wherein the detected measured values are displayed optically. 18. The method according to claim 1, wherein the detected measurement values are stored electrically. 19. Plates or plate parts to be joined which are located above and below one another are deep-drawn together in a single working step by the combined work of the punch (8) and the die (5). , And then partially punching the surface portion, or without punching,
Device for carrying out the method according to any one of claims 1 to 18, for joining thin plates or plate parts arranged one above the other by squeezing and spreading by cold joining. And a die (5) arranged in a mechanical press (1)
And a punch (8) which can be reciprocally moved laterally with respect to the plates to be joined, the position indicator (14) and at least one force measuring device being provided. A device for joining thin plates, characterized in that 20. Device according to claim 19, wherein the signal transmitter is movably (linearly or rotationally) joined to the punch (8). 21. The device according to claim 19, wherein one or more piezoelectric elements are used as the force measuring device. 22. The device as claimed in claim 19, wherein one or more extension measuring strips are used as the force measuring device. 23. A force measuring device (13) is provided in the receiving part of the die (4) or in the press table (3),
Device according to any one of claims 19 to 22. 24. The device as claimed in claim 19, wherein the force measuring device (14) is arranged between the punch (8) and the drive device (10). 25. Device according to claim 24, wherein the force measuring device (15) is provided on the stripper (9). 26. The device according to claim 19, wherein the position indicator (14) is received in the punch stroke limiter (15).