JP4070705B2 - Terminal crimp failure detection device - Google Patents

Description

  The present invention relates to a terminal crimping defect detection device for automatically detecting a crimping failure by monitoring a crimping state of a terminal when crimping a terminal to a terminal of an insulation coated electric wire from which the coating has been peeled off by a terminal crimping device. Is.

  The terminal crimping apparatus automatically attaches a terminal by attaching a terminal having a predetermined shape to a terminal of a covered electric wire that has been cut to a predetermined length and the coating has been peeled off by a predetermined length. That is, a covered electric wire that has been cut to a predetermined length and the end covering is peeled by a fixed length and a terminal having a predetermined shape are fed into a terminal crimping device, and the terminal is mounted on the end of the electric wire on the base plate Place on the anvil. In this state, the terminal is compressed into a predetermined shape by pressing the crimper against the terminal on the anvil from above. Such an operation is continuously repeated to automatically manufacture a large amount of electric wires with terminals.

  In such a terminal crimping device, at the time of terminal crimping, a part of the wire conductor is crimped in a state of protruding from the terminal (the core wire protrudes), and the part to be crimped to the conductor includes a part of the wire coating. Crimping defects such as crimping (resin biting) may occur, and if such crimping defects occur, it is necessary to detect and eliminate them. Therefore, a technology has been developed in which abnormalities during crimping of terminals are detected by a pressure sensor, the crimping state is identified, and defective crimping is automatically detected.

  These terminal crimping failure detection devices capture temporal changes in the pressure sensor output during crimping as waveforms, and compare the peak value and total area of the waveform with those of the reference waveform to determine the quality of the crimped state. . In addition, there is a method in which the waveform is divided into a plurality of regions along the time axis, and the quality of the crimped state is determined by comparing the area of each region with the area of the corresponding region of the reference waveform. Furthermore, the range obtained by shifting the reference waveform by a certain value in the vertical direction is set as the tolerance, and whether the crimped state is good or not is determined by whether the measured waveform is within the tolerance range over the entire waveform. There are also things.

  In such a terminal crimping failure detection device, there is the following method for determining the start time of taking in the pressure waveform. (1) Based on the output signal of the rotary encoder provided on the rotary shaft of the motor that drives the applicator, the timing at which the applicator reaches the terminal crimping position is measured, and the acquisition of the pressure waveform from the pressure sensor is started at that timing. Method. (2) A method of measuring the timing at which the applicator reaches the terminal crimping position based on the ON / OFF signal of the proximity switch provided in the applicator, and starting the acquisition of the pressure waveform from the pressure sensor at that timing. (3) A method of starting taking in a pressure waveform from the pressure sensor when the pressure sensor output exceeds a certain value.

  One of these methods is used to start the acquisition of the pressure waveform from the pressure sensor, and the acquired waveform is compared with the reference waveform to identify the crimping state of the terminal. At this time, the acquisition start time is not always constant, and a time lag occurs in the acquired waveform. Therefore, the waveforms are compared after aligning the acquired waveform and the reference waveform.

For aligning the acquired waveform and the reference waveform, conventionally, as shown in FIG. 7, a reference point P the pressure of the captured pressure waveform from the pressure sensor is maximum, the pressure V _P of the point P The point Q where the line _VQ and the waveform below a certain percentage (for example, 40%) intersect before the point P is used as the reference point. Then, when compared with the reference waveform A, as shown in FIG. 8, the reference waveform detected waveform so that the time axis direction of the position of the reference point Q _B of the reference point Q _A and the detection waveform B matches the A B Adjust by shifting in the time axis direction. In this state, the reference waveform A is compared.

As shown in FIG. 8, the comparison of waveforms is divided into a plurality of regions T _{1 to} T ₃ by dividing lines S _{1 to} S ₄ , and the areas of the reference waveform A and the detected waveform B for each region T _{1 to} T _3. It is done by comparing. At that time, the positions where the partition lines S _{1 to} S ₄ are drawn are set for each type of electric wire and terminal by an engineer based on an empirical rule.

The following documents are related to such a terminal crimping failure detection device.
Tetsuo Sato, “A New Method for Harness Quality Control Using Pressure Sensors”, Mechatronics, Technical Committee, September 1993, Vol. 18, No. 9, P50-53

  However, in the conventional terminal crimping failure detection device, as a method of determining the start time of taking in the pressure waveform, the method using the rotary encoder and proximity switch of (1) and (2) is expensive. Besides, there was a problem that adjustment was difficult. Also, in the method of starting the pressure waveform acquisition when the pressure sensor output of (3) exceeds a certain value, the pressure waveform acquisition is not started unless the pressure sensor output exceeds a certain value. The waveform that appears cannot be captured, and there is a problem that false detection is likely to occur.

  In addition, a line that is below a certain point from the pressure at the point where the pressure of the pressure waveform acquired from the pressure sensor becomes maximum and the waveform intersect before the point, and the waveform acquired using only one point as a reference point If the reference waveform is aligned, there has been a problem that optimum alignment cannot always be performed in various combinations of electric wires and terminals. In addition, when comparing waveforms by area for each area, it requires a high level of skill to properly divide the areas with different pressure waveforms for each item, which is not possible for field workers. was there.

  The present invention has been made in view of such a problem, and an object of the present invention is to make it possible to always perform optimum alignment in any combination of electric wires and terminals. It is another object of the present invention to reliably capture pressure waveforms in all periods from the start to completion of crimping, and to prevent erroneous detection. Furthermore, the object of the present invention is to make it possible to detect crimping defects with high accuracy while eliminating the need for waveform region segmentation that requires skilled techniques when comparing waveforms by area.

In order to solve the above-mentioned problem, the terminal crimping failure detecting device according to claim 1 has been successfully crimped by a pressure sensor that detects a pressure generated at a predetermined position of the terminal crimping device during terminal crimping and the terminal crimping device. A reference waveform generating means for generating and storing a reference waveform based on a temporal change in the output of the pressure sensor at the time, an output waveform of the pressure sensor by comparing the output waveform of the pressure sensor with the reference waveform at the time of inspection And a terminal crimping failure detection device that outputs a terminal crimping failure signal when a difference between the reference waveform and a reference waveform exceeds a predetermined value, and sets priority to a plurality of feature points in the output waveform The waveform is aligned at one point or a plurality of points selected according to the priority order from among the feature points successfully acquired in both the reference waveform and the output waveform .

  Further, the terminal crimping defect detection device according to claim 2 acquires and stores the output waveform of the pressure sensor from before the terminal crimping start by the terminal crimping device, and outputs the output waveform of the entire period from the terminal crimping start to the completion. It is a comparison object of the determination means.

  The terminal crimping defect detection device according to claim 3 selects a specific feature point of the reference waveform, automatically sets a plurality of partition lines based on the feature point, and outputs an output waveform. The terminal crimping failure signal is output by dividing into a plurality of regions and comparing the areas for each region.

  The terminal crimping failure detecting device of the present invention has the following effects.

The terminal crimping failure detecting device of the present invention has the following effects.
That is, the terminal crimping failure detection device according to claim 1 sets priorities to a plurality of feature points in the output waveform, and the priority is selected from among feature points that have been successfully acquired in both the reference waveform and the output waveform. Since the waveform is aligned at one or more points selected according to the order, it is not always clear which feature points will appear in the output waveform. Will be able to do.

  The terminal crimping failure detection device according to claim 2 acquires and stores the output waveform of the pressure sensor from before the terminal crimping start by the terminal crimping device, and determines the output waveform of the entire period from the start of the terminal crimping to the completion of the determination. To be compared. As a result, terminal crimping failure can be detected based on pressure waveforms in all periods from the start to completion of crimping, and erroneous detection is less likely to occur.

  The terminal crimping defect detection device according to claim 3 selects a specific feature point of the reference waveform, automatically sets a plurality of partition lines based on the feature point, and outputs a plurality of output waveforms. By dividing the area into areas and comparing the areas for each area, the terminal crimping failure signal is output, so it is possible to detect crimping failure with high accuracy while eliminating the need for skillful waveform area classification. become able to.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a view showing a state in which a pressure sensor is provided in a terminal crimping apparatus. In FIG. 1, 1 is a base plate, 2 and 2 are applicators, 3 and 3 are crimpers, 4 is an anvil, 5 is a covered wire, 6 is a wire conductor, 7 is a terminal, 8 is a wire barrel, and 9 is an insulation barrel. 10 is a pressure sensor and 11 is a lead wire.

  In the terminal crimping apparatus, a covered electric wire 5 which is cut to a predetermined length, the end covering is peeled by a predetermined length and the electric wire conductor 6 is exposed, and a terminal 7 having a wire barrel 8 and an insulation barrel 9 are provided. The terminal is attached to the end of the electric wire and placed on the anvil 4. In this state, the upper applicator 2 is pushed down, and the crimpers 3 and 3 provided at the lower end of the applicator are pressed against the wire barrel 8 and the insulation barrel 9 of the terminal 7 to compress them into a predetermined shape. .

  As a result, the crimper 3, 3 and the anvil 4 compress the wire barrel 8 of the terminal 7 so as to wrap the wire conductor 6, and the insulation barrel 9 compresses so as to wrap the end of the insulation coating of the covered wire 5. Thus, the terminal 7 is firmly connected and fixed to the covered electric wire 5. The terminal crimping device continuously repeats such an operation to automatically manufacture a terminal-attached electric wire.

  The pressure sensor 10 is provided on the lower side of the base plate 1 of such a terminal crimping apparatus, and the lead wire 11 is drawn out therefrom. As the pressure sensor 10, for example, a piezo sensor having a shape as shown in FIG. 2 can be used. The piezo sensor outputs a voltage proportional to the pressure due to the piezoelectric effect. In the terminal crimping failure detection device of the present invention, pressure is applied to the pressure sensor 10 from the crimpers 3 and 3 via the covered electric wire 5, the terminal 7, the anvil 4, and the base plate 1 when the terminal is crimped. The output of the pressure sensor 10 generated by the pressure is digitally processed, and a normal reference waveform stored in advance is compared with a pressure waveform output at the time of inspection to determine whether the product is good or defective. , To reliably eliminate defective products. In addition, the installation place of the pressure sensor 10 is not necessarily limited to the lower side of the base plate 1, and may be another place as long as the pressure according to the crimping state is generated when the terminal is crimped.

  FIG. 3 is a block diagram of one embodiment of the present invention. The output of the pressure sensor 10 is converted into a digital signal by the A / D converter 12 and input to the CPU 13. The CPU 13 operates according to a program stored in the ROM 14 and executes processing while reading and writing necessary data in the RAM 15. Data received from the A-D converter 12 is processed after passing through a noise filter 18 configured in a software manner.

The data acquisition unit 19 samples the output of the pressure sensor 10 sent via the A / D converter 12 and the noise filter 18 at a predetermined time interval, and a single crimp is always applied to a predetermined area of the RAM 15. Data enough to be included are sequentially recorded in the form of a list of each pressure value. Then, the crimping by the terminal crimping apparatus is started, when the output of the pressure sensor 10 as shown in FIG. 4 exceeds a predetermined value V _S, period until bonding is completed, the output of the pressure sensor 10 in the area After recording, the waveform data for one press including the data before the output of the pressure sensor 10 exceeds the predetermined value V _S is captured from the recorded pressure data and stored in the captured data storage area of the RAM 15. .

As a method for sensing a start crimping, instead of detecting that the output of the pressure sensor 10 exceeds a predetermined value V _S, such as sensing based on the ON / OFF signal of the proximity switch provided on the applicator 2 Other means may be employed.

The waveform data stored in the RAM 15 in this manner is used to obtain the position of the waveform feature point for alignment. As characteristic points of the waveform, (1) the start point and end point of the waveform (points P ₁ and P ₉ in the pressure waveform shown in FIG. 5), (2) the peak point where the pressure value is maximum (same as the point) P ₆ ), (3) Front and rear end portions of the top flat portion (same, point P ₅ and point P ₇ ), (4) Maximum and minimum points in the waveform (same as point P ₂ and point P ₃ ), (5 ) The point where the pressure value becomes a certain value (same point P ₄ and point P ₈ ) can be considered.

  These feature points are determined as follows. That is, the position indicating the maximum pressure value in the data string of pressure values stored in the acquisition data storage area is set as the peak point. Further, in the data string, adjacent data before and after, or adjacent data are sequentially compared, and the first rising point is set as the waveform start point, and the last falling point is set as the waveform end point. Further, in the data string, data adjacent to or adjacent to the front from the peak point are sequentially compared, and the point where the pressure value falls abruptly more than a predetermined value is defined as the front end of the top flat portion, and the peak point The data that are adjacent or close to each other from the rear to the rear are sequentially compared, and the point where the pressure value falls abruptly more than a predetermined value is taken as the rear end of the top flat portion. Also, in the data string, adjacent data before and after the waveform starting point, or adjacent data are sequentially compared backward, and if there are peaks or valleys partially, the position is a maximum or minimum point. To do. Further, the point where the pressure value becomes a certain value may be searched for the position indicating the value from the data string of the pressure value.

  In the terminal crimping failure detection device of the present invention, alignment is performed using these feature points. However, the pressure waveform that appears changes depending on the types of the electric wires and terminals, and their characteristic points do not necessarily appear in all types. Therefore, one or a plurality of feature points are selected from the appearing feature points, and the waveforms are aligned so that their positions match.

  There are the following two methods for performing alignment using one feature point. The first is a method of performing alignment using a feature point having the highest priority. In other words, by setting the priority order for each feature point, select the feature point with the highest priority among the feature points that were successfully acquired in both of the two waveforms to be aligned, and the position of the feature point in the time axis direction Alignment is performed using a difference (hereinafter referred to as “X coordinate”) as an offset. At that time, the priority order may be appropriately set based on an empirical rule.

  The second method, which uses one feature point for registration, simulates the registration for all feature points that have been successfully acquired in both of the two waveforms, and the degree of coincidence of the remaining feature points. Adopt the highest point. That is, the difference between the pressure values of both waveforms at the remaining feature points other than the point used as the alignment reference is obtained, and the case where the average value of the absolute values of the differences is the smallest is employed.

  Next, in the method of performing alignment using a plurality of feature points, a priority order is set for each feature point, and among the feature points that have been successfully acquired in both of the two waveforms to be aligned, the priority order is high. A plurality of points are selected, and the difference between the X coordinates of each point is obtained. Alignment is performed using a value obtained by dividing the two differences by priority as an offset.

For example, in the waveform A and the waveform B shown in FIG. 5, description will be given of a case where alignment is performed using two feature points. A feature point with priority 1 is set as a point P ₁ and a feature point with priority 2 is set as a point P. _In the case of ₉ , when the difference at the point P ₁ is +5 and the difference at the point P ₉ is +8, (5 × 2 + 8 × 1) ÷ 3 = 6, and the alignment is performed with the offset value +6. In addition, when the feature point P ₁ with the priority level 1 cannot be acquired even in any one of the waveforms, the difference between the feature point P _{9 with} the priority level 2 is +8, and the difference with the feature point P _{6 with} the priority level 3 is +6. Then, (8 × 3 + 6 × 2) ÷ 5 = 7.2 is rounded off, and alignment is performed as an offset value +7.

  Before performing the crimping failure detection, first, in order to obtain a reference waveform, crimping is performed several times and waveform data corresponding to the required number is read. At that time, the data is processed while aligning the waveform by the above method. That is, after aligning the waveform data obtained by reading the output of the pressure sensor 10 when it is normally crimped, the reference waveform generation unit 20 samples the waveform data for the read number of the waveform data by sampling at predetermined time intervals. A reference waveform as shown by a waveform A in FIG. 6 is obtained by averaging every time interval, and stored in a predetermined area of the RAM 15. The reference waveform is displayed on the display device 16 by the display control unit 24.

  At the same time, the tolerance generator 21 calculates the standard deviation σ at the predetermined time intervals from the sampled data, and sets -3σ to + 3σ as tolerances with the reference waveform interposed therebetween. Note that the range of -3σ to + 3σ is a range in which about 99.7% of data having a normal distribution is included, and is a value often used for setting a tolerance when performing an error check. Is not necessarily limited thereto, and values calculated by other mathematical expressions can also be used.

  When entering the inspection stage, the data acquisition unit 19 acquires pressure data from the pressure sensor 10 via the A-D converter 12 and the noise filter 18 for each crimping by the terminal crimping device, and detects it. The waveform is stored in a predetermined area of the RAM 15. At that time, as described above, the data sufficient for one crimping operation is always recorded in a predetermined area of the RAM 15 sequentially in a form in which each pressure value is listed, and the crimping by the terminal crimping device is performed. After starting, after the output of the pressure sensor 10 is recorded in the area until the completion of the crimping, the crimping 1 including the data before the start of the crimping is detected from the recorded pressure data. The waveform data for the number of times is fetched and stored in the fetched data storage area of the RAM 15.

  Then, as shown in FIG. 6, the detected waveform B is aligned with the reference waveform by the method described above, and then displayed on the display device 16 in a form superimposed on the reference waveform A by the display control unit 24. The The comparison unit 22 compares the detection waveform stored in the RAM 15 with the reference waveform at each time interval, and outputs a signal outside the tolerance range when the difference between the detection waveform of the pressure sensor and the reference waveform exceeds the tolerance. Output. The determination unit 23 outputs a terminal crimping failure signal via the output unit 17 when the output ratio of the signal outside the tolerance range with respect to the total number of samplings exceeds the set value. In this way, since complete waveform data for one crimping including data before the start of crimping is detected is compared, subtle changes in the waveform immediately after the beginning of crimping, which was apt to be overlooked in the conventional method, are captured. Therefore, it becomes possible to detect inward and outward breaks of the insulating barrel, defective carrier feed of the applicator, defective carrier cutter, and the like.

As a waveform comparison method, as shown in FIG. 8, the waveform may be divided into a plurality of regions by dividing lines, and the areas of the reference waveform A and the detection waveform B may be compared for each region. In that case, highly skilled skill is required to appropriately divide the pressure waveforms that are different for each item by the dividing lines S _{1 to} S ₄ , which is impossible for a worker on site. Therefore, in this terminal crimping failure detection device, the partition line can be automatically drawn.

FIG. 6 is an explanatory diagram of the pressure waveform divided into regions. In the reference waveform A, a specific feature point, for example, a rising point of the waveform and a point at which the pressure value becomes maximum is selected. Then, first searches the rising point P _S wave toward the P ₀ first point of acquired data backwards. That is, the values of adjacent data are sequentially compared, and a point P ₀ is defined as the first point at which a predetermined value or more has continued for a predetermined number of times. Then, among the acquired data, searches the P _P point pressure value is maximized. Then, the pressure waveform is divided into regions based on these two points.

For example, from point P _P rearward, to find the falling point P _A of the pressure waveform. Next, from point P _P forward, looking for the falling point P _B of the pressure waveform. Furthermore, from the point P _P forward, looking for rising point P _C of the pressure waveform. Then, the point _{P S,} the point _{P A,} the point _{P B,} perpendicular _S S passing through the point _{P C, S A, S B} , pull the _{S C,} performs area division of the pressure waveform them as partition lines. In this way, an appropriate partition line can be automatically drawn based on the feature points of the waveform.

It is a figure which shows the state which provided the pressure sensor in the terminal crimping apparatus. It is an external view of a pressure sensor. It is a block diagram of one Example of this invention. It is an explanatory view of taking in a pressure waveform. It is position explanatory drawing of a pressure waveform. It is area | region explanatory drawing of a pressure waveform. It is a figure for demonstrating how to determine the conventional alignment reference point. It is a figure for demonstrating the method of the comparison of the conventional pressure waveform.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base plate 2 ... Applicator 3 ... Crimper 4 ... Anvil 5 ... Covered electric wire 6 ... Electric wire conductor 7 ... Terminal 8 ... Wire barrel 9 ... Insulation barrel 10 ... Pressure sensor 11 ... Lead wire

Claims (3)

A pressure sensor that detects pressure generated at a predetermined location of the terminal crimping device when crimping the terminal;
A reference waveform generating means for generating and storing a reference waveform based on a temporal change in the output of the pressure sensor when the terminal crimping apparatus has successfully crimped;
A terminal comprising: a determination means for comparing an output waveform of the pressure sensor at the time of inspection with the reference waveform and outputting a terminal crimping failure signal when a difference between the output waveform of the pressure sensor and the reference waveform exceeds a predetermined value A crimping failure detection device,
Priorities are set for a plurality of feature points in the output waveform of the pressure sensor, and waveforms are selected at one point or a plurality of points selected according to the priority order from among the feature points successfully acquired in both the reference waveform and the output waveform. The terminal crimping defect detecting device characterized by performing the positioning of. The output waveform of the pressure sensor is acquired and stored before the start of terminal crimping by the terminal crimping apparatus, and the output waveform of the entire period from the start of terminal crimping to completion is used as a comparison target of the determination means. The terminal crimping defect detection device according to 1. A specific feature point of the reference waveform is selected, a plurality of dividing lines are automatically set based on the feature point, the output waveform is divided into a plurality of regions, and the areas are compared for each region. The terminal crimping failure detection device according to claim 1, wherein the terminal crimping failure signal is output.

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