JP2000180273A - Load sensor and wiring harness processing machine using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost load sensor capable of detecting brief change with good response and accuracy. SOLUTION: A load sensor 10 is formed whereby a sensor main body 12 utilizing a super magnetostrictive element 13 is embedded in buried hole 11 formed in a pressure receiving plate 4 for receiving a compressed load between two pressure surfaces. A change in a magnetic field that is produced when a load affects the super magnetostrictive element 13 is detected so that the load can be detected supersensitively with good response. Further, since the length of a load detecting part 14 disposed with the super magnetostrictive element 13 is selected so as to become longer than the depth of the buried hole 11 when a bias magnetic field is applied. Therefore the load can be detected accurately and precisely in which the load detecting part 14 is extended by operating the bias magnetic field and the both ends are surely brought into close contact with each pressure surface even if a slight clearance is produced between the pressure surface and the pressure receiving plate 4 due to dirt and dust that have been caught.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load sensor for detecting a compressive load generated between two pressing surfaces, and a wire harness processing machine using the same.

[0002]

2. Description of the Related Art Electronic devices, including computers occupying the center, various types of information processing, telecommunications, broadcasting, medical care, measurement, education, news reporting, transportation, navigation control, various types of automation, and home appliances, are used in society. It covers all aspects of life.

[0003] Wiring is an indispensable element for all of these electronic devices, and this wiring is roughly divided into general wiring for electrically connecting each component through a covered electric wire or the like,
There is a printed wiring for connecting a component lead wire to a component mounting seat of a copper foil circuit formed by etching or the like.

[0004] Of these, general wiring is often connected using a covered electric wire having a terminal attached to the end, and the terminal is made of copper, brass, phosphor bronze, and the surface thereof is nickel, tin, silver, or gold. It is formed by plating. As a technique for permanently connecting such a terminal to the end of a covered electric wire, soldering and crimping (crimping fitting) are known. Since permanent connection is possible, processing is simple, continuous production can be performed in a short time, and the production cost is low.

A wire harness processing machine is for automatically crimping such a crimp terminal to the tip of a covered electric wire, and automatically feeds the covered wire, automatically cuts the covered portion at the tip, and peels off the covered portion. -Automatic feeding of crimp terminals-A series of crimping operations up to plastic deformation of the crimp terminals by a press machine are continuously performed.

However, if the crimp terminal is not properly crimped to the end of the wire due to a malfunction of the wire harness processing machine or the like, conduction failure may occur over time after the start of use of the electronic device, or the cause is unknown. May cause a failure.

[0007] The cause of poor crimping is that the length of the wire exposed by peeling the coating is insufficient because the stop position of the coated wire automatically fed by the wire harness processing machine is shifted and the cut position of the coated portion is shifted. The crimping terminal of the crimping terminal is pressed by a press machine when the crimp terminal is pressed while the wire is still covered due to stripping failure or the wire is covered. May not be uniformly deformed.

In addition, since the crimping failure is fatal to the electronic device, the operator visually inspects the products one by one at the end of the production line. In addition to the need for skill, if the inspection work is performed continuously for a long period of time, even a skilled worker may be unable to reliably identify defective products and may overlook it.

[0009] Therefore, there has been proposed an apparatus which detects a change in load at the time of crimping by a press machine and automatically inspects the quality of the crimping state based on a load-time curve at that time. FIG. 4 shows such a wire harness processing machine 41.
The press machine 42 includes an applicator 45 that is exchangeably mounted on a bed 43 of the press machine 42 via a base plate 44. The applicator 45 includes a fixed die 47F and a movable die 47M pressed down by a ram 48 of the press machine 42. Each of the dies 47F and 47M is formed in a shape corresponding to the type of the crimp terminal 46.

A load sensor using a piezoelectric element has been proposed as a load sensor 50 for detecting a change in load when the press bonding is performed by the press machine 42. However, since the piezoelectric element has relatively low sensitivity, it is necessary to compensate for this. It is configured as follows.

That is, the base plate 44 includes a lower pressure receiving plate 44D fixed to the bed 43 side and an upper pressure receiving plate 44U to which the applicator 45 is detachably mounted. Protrusions 49 that are in contact with each other are formed along one side, and a gap 51 is formed on the opposite side, and one or two sensor bodies 52 are disposed in the gap 51.

As a result, an extremely large load of about 1/4 of the total load applied to each of the pressure receiving plates 44U and 44D acts on the sensor main body 52, so that even the load sensor 50 using a piezoelectric element having relatively low sensitivity. The load can be detected.

[0013]

However, each of the pressure receiving plates 44U and 44D constituting the base plate 44 is arranged such that the surface of the upper pressure receiving plate 44U is horizontal in a state where the two are combined, and the gaps 51 are parallel. Therefore, a hard metal block such as quenched steel must be cut and accurately formed, which increases the production cost.

Since the response speed of the piezoelectric element is low,
In order to improve production efficiency, when the processing speed is increased, a change in load within the deformation time cannot be accurately detected, and therefore, the quality of the crimped state when the crimp terminal 46 is deformed at a high speed cannot be detected. It was difficult to judge.
In particular, when the movable die 47M is pressed down by the ram 48 so as to be down, the two pressure receiving plates 44U, 4
The 4D bounces and vibrates, so that the load change may not be completely distinguished between a normal time and an abnormal time.

Accordingly, an object of the present invention is to provide an inexpensive load sensor capable of accurately detecting a short-time load change with good responsiveness, and to provide a wire harness processing machine using the load sensor. I have.

[0016]

In order to solve this problem, the present invention provides a pressure receiving plate which receives a compressive load between two pressing surfaces, and an embedding hole which is opened on at least one side of the pressure receiving plate. And a load detecting unit including a giant magnetostrictive element that expands and contracts in the axial direction by receiving a compressive load, and a magnetic field generated when the giant magnetostrictive element expands and contracts. A sensing coil for detecting a change and converting the signal into an electric signal; and a bias magnetic field generating means for applying a bias magnetic field in a direction in which the giant magnetostrictive element is extended. The length when the magnetic field is applied is selected to be equal to or greater than the depth of the buried hole.

The load sensor according to the present invention is formed by embedding a sensor body using a giant magnetostrictive element in an embedding hole formed in a pressure receiving plate that receives a compressive load between two pressing surfaces. The load detecting section provided with the giant magnetostrictive element is selected so that the length when a bias magnetic field is applied without applying a compressive load is equal to or greater than the depth of the embedding hole.

Therefore, when the embedding hole is formed, for example, by penetrating the pressure receiving plate, when the load sensor is disposed between the two pressing surfaces, dust or dust is caught between the pressing surface and the pressure receiving plate. Even if a slight gap is formed, the load detecting section is extended by applying a bias magnetic field to the giant magnetostrictive element, and both ends thereof can be securely brought into close contact with the respective pressing surfaces.

Here, when a compressive load is applied from the pressing surface, the load detecting unit is pressed and the giant magnetostrictive element contracts in the axial direction, and the magnetomotive force of the giant magnetostrictive element changes. Since an electromotive force is generated in the coil, a load change is detected as a voltage change. When a compressive load is applied with an impact or the like, noise is generated due to vibration. Therefore, a load change without noise can be detected by differentiating or integrating this signal waveform. Since the load sensor receives the compressive load acting on the two pressure surfaces over the entire area of the pressure receiving plate, the load on the sensor body is small and the amount of deformation is small, but the load is detected using a giant magnetostrictive element. As a result, it is possible not only to detect a small load change with high sensitivity, but also excellent in response to a high-speed load change.

In addition, the load detecting section can apply both ends of the load detecting section to the pressing surfaces by applying a bias magnetic field to the giant magnetostrictive element and extending the same. It is not necessary to strictly match the pressure (thickness of the pressure receiving plate), and no processing accuracy is required, so that the manufacturing cost is reduced.

If a load sensor is arranged between a bed of a press machine constituting the wire harness processing machine and a fixed die mounted on the bed, the movable die is lowered by the ram of the press machine and fixed. When the crimp portion of the crimp terminal is plastically deformed on the die, a load-time curve corresponding to the deformation behavior is detected, and the load-time curve when deformed normally has substantially the same pattern.

Therefore, the load-time curve pattern when deformed normally is stored in advance, and the detected load-time curve pattern is compared with the previously stored normal load-time curve pattern. This makes it possible to instantaneously determine whether or not the crimp terminal has been crimped normally.

[0023]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic explanatory view showing a wire harness processing machine according to the present invention, FIG. 2 is an explanatory view showing a main part thereof, and FIG. 3 is a graph showing an example of a load-time curve.

The wire harness processing machine 1 according to the present embodiment
It comprises a press machine 2 and an applicator 5 which is detachably mounted on the bed 3 via a base plate 4. The base plate 4 is formed of a hard metal such as hardened steel to a predetermined thickness.

The applicator 5 includes a fixed die 7F which is replaced according to the type of the crimp terminal 6 and positions the crimp terminal 6, and a movable die 7M which is lowered by the ram 8 of the press machine 2. , Each die 7F, 7
M is formed in a shape corresponding to the type of the crimp terminal 6.

When the press machine 2 is started while the applicator 5 is mounted, the movable die 7 M is lowered by the ram 8, and the crimping portion of the crimp terminal 6 is wound so as to wind the tip 9 a of the electric wire 9. 6 a is plastically deformed, and the crimp terminal 6 is permanently connected to the electric wire 9.

A load sensor 10 detects a compression load acting on the fixed die 7 F. The load sensor 10 is a base plate (pressure receiving plate) that receives a compression load between the bed 3 and the applicator 5. 4 and a sensor main body 12 disposed in an embedding hole 11 penetrating the base plate 4.

The sensor main body 12 detects a magnetic field change caused by the expansion and contraction of the giant magnetostrictive element 13 around the load detecting unit 14 having the giant magnetostrictive element 13 which expands and contracts in the axial direction by receiving the compressive load. In this way, a sensing coil 15 for converting the electric signal into an electric signal is formed. Further, the sensing coil 15 also serves as a coil as a bias magnetic field generating means 16 for applying a bias magnetic field in a direction in which the giant magnetostrictive element 13 is extended, so that the size of the sensor main body 12 is reduced. The upper and lower ends of the giant magnetostrictive element 13 are provided with stainless steel caps 14a, 14a for protecting the giant magnetostrictive element 13 from an impact load.

The load detecting unit 14 determines that the length when the bias magnetic field is not applied in the state where no compressive load is applied is the depth of the embedding hole 11, that is, the base plate 4.
Is selected to be approximately the same or less than the thickness of
The length when a bias magnetic field is also applied in a state where no compressive load is applied is selected to be equal to or greater than the depth of the embedding hole 11, that is, the thickness of the base plate 4.

Thus, even if dust or dust is trapped between the base plate 4 and the applicator 5 or the bed 3 to form a slight gap, the load detection unit 14 can be configured by applying a bias magnetic field to the giant magnetostrictive element 13. It is extended and its upper end is tightly attached to the lower surface of the applicator 5 serving as the pressing surface, and its lower end is closely contacted to the surface of the bed 3 serving as the pressing surface, so that the load can be accurately detected.

Although not shown in the drawings, the wire harness processing machine 1 includes an automatic feeding mechanism for a covered electric wire, an automatic cutting mechanism for a coating portion at a tip, a stripping mechanism for a coating portion, and an automatic feeding mechanism for a crimp terminal. For these configurations,
It is the same as a conventional general wire harness processing machine.

The above is an example of the configuration of the present invention, and its operation will be described below. First, an applicator 5 having a fixed die 7F and a movable die 7M according to the type of the crimp terminal 6 is mounted on the bed 3 of the press machine 2 via the base plate 4.

This base plate 4 is a load sensor 10
Since the sensor main body 12 is provided in the embedding hole 11 formed so as to penetrate through the base plate 4,
When a bias magnetic field is applied by the coil 16, the giant magnetostrictive element 13 expands, the load detecting section 14 extends in the protruding direction from the embedding hole 11, and the upper and lower ends thereof are brought into close contact with the lower surfaces of the bed 3 and the applicator 5, respectively. Be abutted. Thus, a bias magnetic field is applied to the giant magnetostrictive element 13 and a prestress is applied, so that the load can be detected with extremely high sensitivity.

[0034] Then, the crimp terminal 6 is fixed on the fixed die 7F.
After the tip 9a of the wire 9 whose coating has been stripped is loosely mounted on the crimping portion 6a of the crimp terminal 6, the press machine 2 is started. As a result, the ram 8 pushes down the movable die 7M, and the crimp portion 6a of the crimp terminal 6 on the fixed die 7F.
Is instantaneously deformed in a short time of about 30 ms, and the distal end portion 9a of the electric wire 9 is wound around the right and left sides by the deformed crimp portion 6a, and the crimp terminal 6 is permanently connected to the electric wire 9.

During this time, the fixed die 7F is moved to the movable die 7
M, the load acts downward from the applicator 5 provided with the fixed dies 7F toward the bed 3, and as a reaction, the applicator 5
, An upward reaction force is generated.

As a result, a compressive load acts on the load sensor 10 disposed between the applicator 5 and the bed 3, and the thickness of the base plate 4 and the length of the load detecting unit 14 change according to the load. . As a result, the length of the giant magnetostrictive element 13 arranged in the load detecting section 14 changes, and a magnetic field change occurs in the giant magnetostrictive element 13, so that an electromotive force is generated in the sensing coil 15 due to the change in the magnetic field. Further, since a shock is generated when a compressive load is applied and noise is generated due to vibration, a load change without noise can be detected by differentiating or integrating the signal waveform of the electromotive force.

At this time, the sensor body 12 is disposed in the embedding hole 11 formed in the base plate 4, and its area is extremely small as compared with the entire base plate 4 on which the load acts, so that the load acts. Even if it is mounted directly below, the load received by the sensor body 12 varies depending on the sensor mounting position, but is generally 1/10 to 1/1 / of the total load.
It will be about 20.

Therefore, even if a large load acts on the load sensor 10 by rolling down the movable die 7M, the load acting on the sensor main body 12 becomes extremely small, so that the sensor main body 12 is not broken. Note that even if the load acting on the sensor body 12 is small, the load can be detected by the giant magnetostrictive element 13 arranged in the load detection unit 14, so that the detection can be performed with high accuracy. The time during which the fixed die 7F receives a load from the movable die 7M is extremely short, about 30 ms. However, since the giant magnetostrictive element 13 is excellent in high-speed response, a short-time load change can be detected very accurately. can do.

FIG. 3 shows an example of the load-time curve detected in this manner. As shown in FIG. 3A, the normal load-time curve has three downward peaks. Peak P ₁ of the first is caused by the impact when the movable die 7M hits the crimping portion 6a tip of the crimping terminal 6 is pressure peak P ₂ of the second is by further reduction of the movable die 7M crimp terminal occurs when the crimping portion 6a of 6 is buckled and deformed, the maximum of the peak P ₃ of third occurs when the ram 8 is crimped portion 6a reaches the lower end position is tightly wound bite the wire 9.

FIG. 3 (b) is a load-time curve when the crimp terminal 6 is crimped to the wire 9 having a thin end portion 9a by pulling out the conductor when the coating is peeled off. the value of P ₃ is smaller. FIG. 3 (c) load when brought into crimp the crimping terminal 6 to the wire 9 that coating does not peel off - a time curve disappears peak P ₂ of second,
The value of the _third peak P3 is large.

As described above, the load-time curve in the case of normal deformation is stored in advance and, for example, the presence or absence of each of the peaks P ₁ , P ₂ , P ₃ and the respective values are compared, so that the crimping is performed. It is possible to automatically determine online whether or not the terminal 6 has been deformed normally without visual observation.

In the above description, the embedding hole 11 is
The case where the base plate 4 is penetrated so as to open on both sides is described, but the present invention is not limited to this, and even if the embedding hole 11 is opened on one side of the base plate 4. Good.

In this case, if the length when a bias magnetic field is applied without applying a compressive load is selected so that the length when the bias magnetic field is applied is equal to or greater than the depth of the embedding hole 11, the load detector 14 detects the bias magnetic field. When the voltage is applied, one end of the load detector 14 is in close contact with the bed 3 or the applicator 5, and the other end is in close contact with the bottom of the embedding hole 11, so that the load generated between the bed 3 and the applicator 5 is as described above. It can be detected similarly.

Further, the case where the sensing coil 15 of the sensor main body 12 also serves as the coil 16 as the bias magnetic field generating means has been described, but it is needless to say that the respective coils may be formed separately. However,
There is a merit that the sensor body 12 itself can be reduced in size when used in combination.

Further, the case where one sensor main body 12 is arranged on the base plate (pressure receiving plate) 4 has been described. However, the number of sensor main bodies 12 to be installed is arbitrary. The total sum of the loads output from 12 may be detected as the total load.

Further, the wire harness processing machine 1
Are fixed dies 7F on an applicator 5 which is attached to and detached from a bed 3 of a press machine 2 via a base plate 4.
Although the description has been given of the case where the movable dies 7M are arranged, the present invention is not limited to this, and the case where the fixed dies 7F are directly mounted on the base plate 4 and the movable dies 7M are mounted on the ram 8 may be employed.

[0047]

As described above, according to the load sensor according to the present invention, since the sensor main body is simply housed in the sensor embedding hole formed in the pressure receiving plate, the pressure receiving plate is It is only necessary to perform processing for forming the sensor embedding hole, and no other complicated processing is required, so that the manufacturing cost can be reduced.

Further, since the giant magnetostrictive element is used in the load detecting portion of the sensor body, it can be used as a load detecting sensor having high sensitivity and excellent high-speed response, and the giant magnetostrictive element is relatively inexpensive. And the structure is simple,
There is also an effect that the manufacturing cost can be reduced.

Further, even if a small gap is formed between the pressing surfaces and the pressure receiving plate due to dust or dirt, a load magnetic field is applied to the giant magnetostrictive element to extend the load detecting portion. Has a very excellent effect that it can be closely contacted with each pressing surface without any gap, and the load can be detected accurately.

Further, according to the wire harness processing machine of the present invention, the instantaneous load change when the movable die is pressed down by the ram of the press machine to plastically deform the crimp portion of the crimp terminal on the fixed die is reduced. Since it can be detected accurately, the load waveform when deformed normally is stored in advance, and by comparing this with the detected load waveform, it can be determined whether the crimp terminal has been crimped normally. It has an excellent effect that online and instantaneous and reliable judgment can be made.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a wire harness processing machine according to the present invention.

FIG. 2 is an explanatory view showing the main part.

FIG. 3 is a graph showing an example of a load-time curve.

FIG. 4 is a schematic explanatory view showing a conventional device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wire harness processing machine 2 ... Press machine 3 ... Bed 4 ... Base plate (pressure receiving plate) 5 ... Applicator 6 ... Crimp terminal 6a ... Crimp part 7F ... Fixed die 7M ··· movable die 8 ··· ram 9 ··· wire 9a ··· tip end 10 ··· load sensor 11 ··· embedded hole 12 ··· sensor body 13 ··· giant magnetostrictive element 14 ··· Load detector 15 ・ ・ ・ Sensing coil 16 ・ ・ ・ Bias magnetic field generating means

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroshi Abe 471 Onna, Atsugi-shi, Kanagawa F-term in Advanced Circuit Technologies Inc. (reference) 5E063 CB20 CC05 CD30

Claims (5)

[Claims] 1. A pressure receiving plate (4) receiving a compressive load between two pressure surfaces, and a sensor disposed in an embedding hole (11) opened on at least one side of the pressure receiving plate (4). Body (1
2), the sensor body (12) comprises a load detecting section (14) including a giant magnetostrictive element (13) that expands and contracts in the axial direction under a compressive load, and the giant magnetostrictive element (13) A sensing coil (15) for detecting a magnetic field change caused by expansion and contraction and converting it into an electric signal, and a bias magnetic field generating means (16) for applying a bias magnetic field in a direction in which the giant magnetostrictive element (13) is extended. Together with the load detector (14)
The load sensor according to claim 1, wherein a length when a bias magnetic field is applied without applying a compressive load is selected to be equal to or greater than a depth of said embedding hole (11). 2. The embedment hole (11) is formed to penetrate the pressure receiving plate (4), and the length of the load detecting portion (14) is set by applying a bias magnetic field without applying a compressive load. 2. The load sensor according to claim 1, wherein the load sensor is selected so as to be sometimes thicker than the thickness of the pressure receiving plate. 3. The load sensor according to claim 1, wherein said sensing coil (15) also serves as said bias magnetic field generating means. 4. A movable die (7M) for a fixed die (7F) mounted on the bed (3) side of the press machine (2).
In a wire harness processing machine for crimping the crimp terminal (6) to the tip (9a) of the electric wire (9) by plastically deforming the crimp portion (6a) of the crimp terminal (6) by lowering A pressure receiving plate (4) that receives a compressive load between (3) and the fixed die (7F), and is disposed in an embedding hole (11) opened on at least one side of the pressure receiving plate (4). A load sensor (10) including a sensor body (12), wherein the sensor body (12) includes a giant magnetostrictive element (13) that expands and contracts in the axial direction by receiving a compressive load;
A sensing coil (15) for detecting a magnetic field change caused by expansion and contraction of the giant magnetostrictive element (13) and converting the magnetic field into an electric signal; and applying a bias magnetic field in a direction to extend the giant magnetostrictive element (13). A bias magnetic field generating means (16), and the load detector (14) has a length when a bias magnetic field is applied without applying a compressive load,
A wire harness processing machine selected to have a depth equal to or greater than the depth of the embedding hole (11). 5. An applicator (5) to which different fixing dies (7F) are attached according to the types of the crimp terminals (6) is connected to the bed (3) via a pressure receiving plate (4) of the load sensor (10). 5. The wire harness processing machine according to claim 4, wherein the wire harness processing machine is detachably mounted on the wire harness processing machine.