DE102007033153A1 - Procedure for quality testing of a joint formed between plate or sheet metals and similar materials, comprises determining interlocking button thickness and comparing the determined button thickness with a measuring value - Google Patents

Abstract

The procedure for quality testing of a joint formed between plate or sheet metals and similar materials with the help of a machine tool by mechanical fastening methods such as clinching, punch riveting and clinch riveting that employ non-destructive reshaping techniques without use of additional components for joint formation, comprises determining interlocking button thickness that is specified according to the production of the joint spot by deep-drawing and roll-forming with the help of a punch and a button, and comparing the determined interlocking button thickness with a measuring value. The procedure for quality testing of a joint formed between plate or sheet metals and similar materials with the help of a machine tool by mechanical fastening methods such as clinching, punch riveting and clinch riveting that employ non-destructive reshaping techniques without use of additional components for joint formation, comprises determining interlocking button thickness that is specified according to the production of the joint spot by deep-drawing and roll-forming with the help of a punch and a button, and comparing the determined interlocking button thickness with a measuring value that is given as the specified value, with the help of an electrically-controlled program with a test sample, which is recorded by a measuring device (13) that is calibrated by the machine tool. The measuring device has a corresponding joint spot. The comparative value lies within a given interval of measurement results. The manufacture is interrupted or a warning signal is given, if the comparative value falls out from the specified interval of measurement results. The interlocking button thickness at the machine tool is calibrated by comparing the measured results from the measuring device of the specified value and the interlocking button thickness. For the comparison of the measurement results, errors are caused by the force-dependent changes of the distance between the punch and the button that remains after the reshaping mechanical fastening process and determines the interlocking button thickness, as in the case of machine tools with an open-sided housing or the like. A calibration nullifies or corrects the error, which is carried out by a computer that processes the measured values. The calibration or the correction during the production process takes place automatically with the help of the computer. The machine tool serves itself as a tool for quality testing by the calibrated measuring device. Independent claims are included for: (1) machine tool for clinching for connection of plates, sheet metals etc; and (2) measuring device for measuring interlocking button thickness of a joint spot produced in the clinching process.

Description

State of the art

The The invention is based on a method for checking the quality of a Clinching connection according to the preamble of the main claim and a machine tool or Measuring device for implementation The method according to claims 7 and 10.

at the connection of superimposed workpieces, in particular thin plates, sheets, Plate sections or the like by clinching, namely clinching, punching riveting, clinching The like, creates a so-called joint point, whose after the manufacturing process resulting so-called residual bottom dimension, namely the thickness in the area the bottom of the joining point, a feature for the quality represents the same. The joining point is by the machine tool during clinching by means of a punch and a die made, the quality of the joint point produced over a suitable measuring device, for example, the so-called X-scale, by Determining the soil thickness is determined randomly.

At the Clinching or clinching, this so-called residual bottom dimension is the actual remaining one Total thickness within the joining point and therefore has to be measured in the middle of the joint point bottom. For stamping or clinch riveting, on the other hand, for the residual bottom dimension, the Height of compressed rivet considered become. In any case, is for the residual soil measure desired target range within which the measured Actual value of the residual floor measure should lie.

It is known to check the quality of the joining point by measuring the pressing force at the end of the joining operation, by comparing this with an entered desired value ( EP 0 642 853 B1 ). In this method of pressing force measurement is closed by a computer and a corresponding program, but only indirectly, on the residual soil thickness, so that the quality statement on the joining point is only indirect.

In another known method for monitoring the joining process during clinching ( DE PS 102 08 304 C1 ) are repeatedly coupled during the joining process ultrasonic pulses in the components to be joined and it is the running times of the reflected at an interface between the components ultrasonic pulses measured. These transit times are then compared with target transit times which have been determined or predefined for each of the components in advance, taking into account a material-specific speed of sound for the desired joint thickness changed by plastic deformation of the components upon reaching a nominal joint thickness relative to an initial state , Also in this method is only indirectly, namely on maturities, or ultrasonic pulses, closed on the quality of the joint, so that here too the quality statement is made without direct examination of the residual soil thickness.

In another known method for testing the quality of a connection point produced during clinching by means of at least one eddy current sensor through which the entire form-fitting connection of the connection point produced by the clinching is penetrated by an eddy current field, wherein the measurement signals obtained by means of the eddy current sensor for determining the degree of compression of the positive connection be used ( EP 1 459 819 A2 ). It is therefore also only an indirect test of the quality of the joint point, which is then closed on the residual soil thickness.

In a generic known method for determining the residual bottom dimension ( DE 103 27 886 A1 ), the ground thickness is calculated by detecting the measurable process signals present during the clinching, such as force, pressure and displacement signals, as well as a measured position value, for example of the punch, and taking into account the bending factor of the clinch device, namely via a calculation algorithm. Thus, apart from the measurement of the position value, everything has already been known beforehand by the prior art (see EP 0 642 853 B1 ). Also in this method, therefore, the determination of the residual soil thickness is only indirectly, but with the help of a computer program.

For an immediate exam the quality of the Connection point over its residual soil thickness must also in other known methods repeatedly interrupted the production and by means of a so-called X-Maßtasters at a finished joining point checked be whether the actual value of the residual soil measure within a given Target range is. This review must at regular intervals. The measurement quality depends, however very strongly from the operator of the probe, since already a small eccentricity or skew of the probe in relation to the joining point can lead to a significant error in the measurement result. Because the joining points on the produced workpieces sometimes difficult or impossible to access, is this type high-quality assurance, costly and awkward. An adequate quality check will certainly not achieved in this way.

The invention is based task

Of the Invention is the object of a method for quality testing Enforce or To achieve penetration rivets, in which the residual soil measure after production of the joining point immediately determined and tested in order to thereby timely irregularities in production to recognize or less dependent from the examiner or to be operator.

The invention and its advantages

The inventive method for the quality control of a produced by clinching Connection with the characterizing features of the main claim and the characterizing features of the machine tool according to claim 7 or measuring device according to claim 10 has the other hand Advantage that a substantial independence from the examiner or Operator of the plant is there and thereby irregularities in the production the joining points be recognized in time. Due to the independence of machine tool and measuring device, but common processing the measurement data Calculator, lets the test result directly on the setting or calibration of the machine tool use. When crossing an approved nominal value range of the measurement result, the Production can be interrupted, but it can, especially in design of the invention, a calibration of the machine tool with respect to made the manufacturing error, for example, a too high pressing force or too short a stroke of the stamp or the like.

at the machine tool can be, in particular, a clinching tongs, Rivet pliers or the like for the preparation of the Durchsetzfügung of a residual Bodenmaß having joining point act. The measuring device can be used to measure the residual bottom dimension of a by means of the machine tool, in particular a clinching pliers, riveting pliers or the like, manufactured joining point a test pattern serve, which must be calibrated according to its size should, by using the means of production of a clinching or riveting device As a machine tool, the calibrated measuring device provides improved monitoring results.

By the creation of the test pattern directly through the machine tool and its punch and die this results in a joint point with a certain residual floor dimension that is sought. In the process monitoring with the help of the measuring device, which continuously detects this predetermined joining point and compared with what is actually produced in the machine tool, a corresponding process monitoring takes place. Because the measuring device extremely accurate the measurement measured on the test sample is also very accurate, so that when comparing with the produced joining points deviations immediately be recorded. Once a deviation of the two values from each other determined by the computer can, according to embodiment of the invention, also the machine tool be recalibrated.

To An advantageous embodiment of the invention are in the measurement comparison Considered errors by force-dependent changes of the between punch and die after the clinching existing and determines the Restbodenmaßenden Distance considered as they are in machine tools with unilaterally open housing, such as For example clinching pliers or rivet pliers, can arise and what about the automatically the measured values processing computer to the machine tool a correction or calibration can lead to the production. This is mainly about one of the operating force on the machine tool dependent change at the distance between the punch and die, the X-distance, which is as a result of the housing open on one side by its resilient Yielding during production results.

The Measuring device operates according to the invention with a transducer whose facing the joining point Centered centrically to the center of the joining point is to determine an accurate value, with the encoder axially slidable in a serving to avoid Aufbiegefehlern Frame is arranged.

To an additional one advantageous embodiment of the invention, the bending takes place or the change on the frame of the machine tool, resulting in an X-measure change leads and via a strain sensor can be measured. The special advantage of processing the individual measured values from housing bending of the machine tool, remaining ground measurement of the product as well the test pattern and with processing of these results in the computer, a expandable test at Clinching especially with automatic calibration while production possible is.

advantageously, is done by the use of a manufactured by the machine tool test specimen as well as continuous measurement of the same and its comparison to ongoing manufactured product at joining points An immediate quality inspection takes place an indirect determination of the residual soil measure. Of course it is possible, such measurement comparisons in adaptation to production at regular intervals make.

By creating the test pattern unmit Directly from the machine tool and the tools (punch and die), this results in a joint point with a desired residual bottom dimension which is continuously recorded during process monitoring. This measurement is measured on the test sample and compared with the values displayed in the process monitoring of the produced joining points via the measuring device with its extremely accurate measuring sensors. If the two values deviate from one another, the process control can be used to calibrate the machine tool for the production of the joining points to the measured value.

The has measuring device according to the invention also additional Advantages on, such as, due to the reproducible Measurement results, allow a calibration of the machine tool, as described below. Of course, the measuring device also has to even regularly with Calibration standards such as gauge blocks are calibrated.

comparing one the spread of the measurements of the residual soil strength of usual today manual Measurements with the spread of o.a. automated (in situ) Measurements, you can typically see a significant reduction. This has the following advantage: From the point of view of joining technology, it is possible for everyone joining point an area for the remaining floor thickness is set, within which the addition as good quality can be called. The effective usable range is the bigger, ever smaller is the spread of the measuring means. That the usable process width can through the use of o.a. the measuring procedures are increased.

Further Advantages and advantageous embodiments of the invention are the following description, the drawing and the claims.

drawing

In the drawing is an embodiment of Measuring device described in detail.

It demonstrate:

1 a measuring device in longitudinal section,

2 the measuring device off 1 on a slightly larger scale,

3 a step out 1 on a much larger scale,

4 a section of a machine tool concerning the pliers,

5 a diagram to explain the function and

6 one 5 corresponding diagram.

Description of the embodiment

In 1 is a specially developed for the inventive method, according to the invention measuring device shown. This measuring device has a frame 1 on with handles 2 and a centrally located measuring tool 3 , The measuring tool 3 indicates with the frame 1 connected support part 4 on, with a guide axis 5 on the contrary to the force of a spring 6 a clamping part 7 slidably arranged. On this clamping part 7 is a plate-shaped test pattern 8th applied, which has a second clamping part 9 held in a horizontal position perpendicular to the guide axis 5 stands. Also this clamping part is by a spring 10 loaded. Through this clamping part 9 also extends in the vertical direction a transducer 11 with a measuring tip 12 , the upper end of the clamping part 7 in the opening of the test sample 8th existing connection point emerges. Through the measuring tip 12 thus becomes the bottom of the test pattern 8th touched on the side facing away from the opening in the test pattern. The thus determined position of the encoder 11 is via a measuring device not described in detail 13 recorded for any further processing.

The 2 and 3 show the measuring device according to the invention 1 in slightly or greatly enlarged scale.

According to the invention, the measuring device according to the invention is also used for calibrating a production machine tool, here in FIG 4 in the form of a clinching forceps 15 shown used. The measuring device according to the invention provides precise and reproducible measurement results, in particular in that the measuring tip 12 centric attacks in the center of the dot, which is also ensured by the fact that the test pattern exactly at right angles to the encoder 11 are arranged during measurement.

For an interaction of the measuring device with the in 4 illustrated pliers 15 an adjustment of the machine tool takes place, namely as follows:
For the calibration of the pliers, blanks of defined geometrical dimensions can be held and joined in the pliers opening. The residual floor thickness value displayed in the associated process monitoring is recorded. Subsequently, the joined sheets are placed as a test pattern in the described measuring device and the residual soil thickness precisely measure up. The two values for the residual floor thickness are compared and the machine tool is recalibrated via process monitoring. The difference to the previous calibration as well as to the original calibration can be recorded and compared with a target value to detect an early detection of irregularities. Here, above all, it must also be taken into account that a bracket 14 the pliers 15 by the dimension X bends in the preparation of the joint point, as in 4 is shown. This bend is known to be due to a strain sensor 16 measurable. The working piston of the machine tool moves internally always to a fixed stop or an electrospindle drive to a specific position, so that the distance between a stamp 17 and flange of the working piston is constant, as long as this fixed stop is not changed. The bend, however, of the temple 14 is proportional to the force that the punch has over the workpiece on a die 18 exercises. Thus, the X-dimension is adjustable via the internal fixed stop.

As long as this stop or the tool is not changed, fluctuations in the X-dimension are basically caused by variations in the Bügelaufbiegung. These in turn are via the strain sensor 16 measured. The pliers must be calculated so that the X-dimension can be calculated from the determined bending 15 However, once basal calibrated.

As in 5 and 6 Two clinching processes are shown for the basic calibration 19 and 20 performed with different laminated core thickness. It should be the first clinching process 19 be made with the original sheet pairing and the second clinching process 20 with only one sheet. Based on the force values and the measured X dimensions of these two clinch processes 19 and 20 Process monitoring calculates the straight line 21 "Bent-up / X-dimension". With this line 21 For each additional clinching process, the associated X-dimension can be determined via the measured bend.

Due to the basic calibration is thus the slope of the line 21 "Bend / X-measure" and the Y-axis section ie the theoretical X-measure calculated at bend 0. The slope reflects the bending of the system, while the Y-axis section reflects the distance between the stamp 17 and die 18 represents. If it is determined during the regular inspection of the joining tongs that the displayed X-dimension deviates from the measured X-dimension, the Y-axis offset must be corrected. To calibrate the Y-axis section (offset), a recalibration is performed in which a clinching process is performed with calibration plates of the original plate pairing.

Based on the measured bending and the X-measure determined by the measuring device, the straight line becomes 21 "Force / X measure" shifted in parallel until it passes through the current point.

All in the description, the following claims and the drawing Features can both individually and in any combination with each other invention essential be.

1

frame

2

Griffen

3

measuring device

4

supporting part

5

guide axis

6

feather

7

tensioning part

8th

samples

9

tensioning part

10

feather

11

Transducers

12

Probe

13

measuring device

14

hanger

15

tongs

16

strain sensor

17

stamp

18

die

19

clinch process

20

clinch process

21

Just

Claims (12)

Method for quality control of clinching, punch riveting, clinch riveting udgl. made by a machine tool connection between plates, sheets udgl. and determining the residual floor thickness given after the production of a connection point obtained by deep drawing and crimping by means of a punch and a die, characterized in that the determined residual floor dimension is recorded by means of an electrically controlled program with a measuring device calibrated independently of the machine tool, a corresponding connection point having, test pattern is compared with a predetermined as a target value measured value. Method according to claim 1, characterized in that that the benchmark is within an approved range of Result of the measurement is, and when the span is exceeded the Production interrupted or a warning signal is given. A method according to claim 1 or 2, characterized in that the latter can be calibrated by comparing the measurement results from the measuring device of the desired value and the residual bottom dimension of the machine tool. Method according to claim 3, characterized that in the measurement comparison errors are taken into account by force-dependent changes of the existing between punch and die after the clinching and determining the residual soil measure Distance arise, as in machine tools with unilaterally open Housing or the like, and being over the computer processing the measured values on the machine tool an error compensating or correcting calibration is feasible. Method according to claim 4, characterized in that that calibration or correction in the manufacturing process automatically with the help of the computer. Method according to one of the preceding claims, characterized characterized in that the machine tool by means of the calibrated Measuring device itself serves as a means of quality inspection. Machine tool for clinching for joining plates, sheets udgl. with the help of a deep drawing and squeezing of the workpiece causing stamp ( 17 ) and die ( 18 ) and with detection of the residual floor thickness on the workpiece after the clinching operation via a transducer device and transmission of the measured values to a computer processing the measured values, characterized in that - via a measuring device operating independently of the machine tool ( 3 ) a calibrated test pattern specifying a target value ( 8th ) is measured, the bottom thickness is detected and also transmitted to the computer and - that leads by comparing the measured values, a deviation from a predetermined target value range to a corresponding signal or shutdown or self-calibration of the machine tool. Machine tool according to claim 7, with a function of the actuating force during the insertion-changing gap between the punch ( 17 ) and die ( 18 ) as a result of a housing which is open on one side ( 14 . 15 ) - in particular clinching tongs, rivet tongs udgl. - which is due to the change in distance between stamp ( 17 ) and die ( 18 ) (X-distance) resulting change in the computer is taken into account. Machine tool according to claim 8, characterized that when enforcing resulting errors due to the bending of the housing over a Strain sensor is detected, the measured data are fed to the computer. Measuring device for measuring the residual bottom thickness of a joining point produced by clinching, in particular for carrying out the method according to one of claims 1 to 6, or in conjunction with the machine tool according to claim 7 to 9, characterized in that the measuring device ( 3 ) a transmitter ( 11 ), whose end facing the joining point is aligned centrally to the joining point center and that in the measuring device ( 3 ) a test sample ( 8th ) is measured, the residual soil thickness is processed with that of the joint point produced in the machine tool in the common computer. Measuring device according to claim 10, characterized in that the encoder ( 11 ) is arranged perpendicular to the superimposed workpieces. Measuring device according to claim 10 or 11, characterized in that the encoder ( 11 ) axially displaceable in a serving to avoid centering errors frame ( 1 ) is arranged.