JPS6321802A - Trimmer of resistor - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a trimming device for a resistor for adjusting resistance value, and specifically has a cylindrical shape such as a carbon film resistor or a metal film resistor. The present invention relates to a trimming device for a fixed resistor using a film resistance element.

Conventional Technology A film resistor is constructed by press-fitting metal camps onto both ends of a cylindrical film resistance element. Generally, a resistance film is formed on the surface of a cylindrical insulator, and then a spiral-shaped film is formed on the resistance element. There is a trimming process that aims to increase the resistance value to a predetermined value by performing trimming to provide a portion where the film is removed. Conventionally, in this process, the devices for spirally trimming the resistive film as described above can be roughly divided into two types: devices that grind away the resistive film by rotating a thin disc-shaped grindstone at high speed, and devices that use a laser beam to trim the resistive film onto the resistive element. There was a device that condensed light to locally evaporate and remove the resistive film.

The former device using a disc-shaped grindstone was as shown in Fig. 7. In other words, a film resistor 1 with a resistance film coated on the surface of a cylindrical insulator was used like a vibrating parts feeder. The film resistor 1 is fed by a suitable aligning and feeding device (not shown), held between chucks 2 and 2a, and moved at a constant speed in the axial direction while rotating the film resistor 1, and a thin disc-shaped grindstone 3 is rotated at high speed. It has a structural function of trimming the resistive film in a spiral shape by applying the resistor while applying the resistor, and when a predetermined resistance value is measured, the disc-shaped grindstone 3 is separated and released from the resistor. Further, in FIG. 7, reference numeral 4 denotes a spindle consisting of a shaft 4a and a bearing 4b, which serves to rotate the grindstone 3. 5 is the spindle 4 mentioned above.
The spindle 4 is rotationally driven by a 6° motor, a large pulley 7, a small pulley 8, and a belt 9.

As a mechanism for applying the disk-shaped grindstone 3 to the film resistor 1, a mechanism as shown in FIG. 8 has generally been used.

That is, a cutter holder 5 containing a spindle 4 for rotating a disc-shaped grindstone 3 is supported by a fulcrum 10, and a weight 11 is supported by a fulcrum 10.
By adjusting the position of the disc-shaped grindstone 3, the force for pressing the disc-shaped grindstone 3 against the film resistor 1 is adjusted, and the cam 12 pushes the disc-shaped grindstone 3
The timing was taken to apply the voltage to film resistor 1. In addition, in FIG. 8, 13 is a cutter holder holder, and 14 is a cutter holder holder.
1 is a weight shaft, 15 is a cam lever, and 16 is a fulcrum.

In addition, in this adjustment device, in order to generally cut a good groove, the rotating surface of the disc-shaped grindstone 3 is set at an angle θ with respect to the film resistor 1, as shown in FIG. Groove 1
I adjusted it to match 7.

In addition, the latter device using laser light has a resistive element feeding mechanism and a spindle chuck mechanism similar to the device using the disc-shaped grindstone described above, as well as a laser oscillator and an optical system for focusing the laser beam. The grindstone mechanism of a device that uses a disk-shaped grindstone is replaced with a laser generating mechanism.

Problems to be Solved by the Invention Among such conventional trimming devices, devices using a disc-shaped grindstone and resistors trimmed with the same have the following problems.

(1) Trimming is performed by rotating a disc-shaped grindstone at high speed and applying it to the film resistor, which applies thermal and mechanical stress to the film resistor, leaving fine cracks on the edges of the groove.
These factors cause deterioration of electrical characteristics. Furthermore, as the temperature of the film resistor increases, the resistance value becomes different from that at room temperature due to the temperature characteristics of the resistance film, which tends to cause a resistance value measurement error when adjusting the resistance value.

(2) As shown in Fig. 8, since the contact between the cutting edge of the disc-shaped grinding wheel 3 and the film resistor 1 is made only by the weight of the cutter holder 5, etc., the blade edge is pre-empted, especially at the start of grooving. occurs and the groove depth and groove width fluctuate. Furthermore, when the disc-shaped grindstone bounces on the film resistor, it causes groove jumping, which causes deterioration of the electrical characteristics of the film resistor as a product.

(3) To prevent groove skipping and groove defects mentioned in item (2) above,
The disc-shaped grinding wheel must be pressed against the film resistor with a certain degree of force, which results in the formation of a deep groove of several tens of micrometers. This situation is shown in Figure 1O.
17 is the deep groove mentioned above. As shown in FIG. 10, the thickness of the portion of the resistance film 19 existing on the surface of the resistor insulator 18 constituting the skin ll* resistor, including the surface roughness of the resistor insulator 18, is several μm or less. be. therefore,
The mechanical bending strength of the resistor body is extremely reduced due to the deep groove 17 described above.

This is undesirable because it may cause the film resistor to break, for example, when the film resistor is inserted into a printed circuit board using an insert machine.

Also, by cutting the resistor insulator deeply, a large amount of insulator dust made of alumina etc. is generated, but this dust is not only harmful to the human body (but can also clog the precision parts of other machines). Interfere with normal function.

(4) When the disc-shaped grindstone wears and its diameter becomes smaller, the groove condition deteriorates, and the resistance value after trimming deviates from the target due to the timing difference between the start and end of cutting, which may affect the position of the cutter holder. Adjustments are necessary and this will lead to a decrease in productivity.

(5) As shown in Figure 10, the edges of the grooves are sharp, so it is easy to damage the resistance film of other film resistors and the plating of the terminal camps during product transportation, and the edges of the grooves themselves can also chip and resist resistance. The value may change, or the plating of the terminal cap of another film resistor may adhere to the resistor film, deteriorating the electrical characteristics.

(6) If the film resistor fails to be inserted into the chuck and is chucked eccentrically, causing the film resistor to rotate eccentrically, an impact will be applied to the cutting edge of the disc-shaped grindstone, causing part of the blade to It causes chipping. If a part of the blade is chipped in this way, the condition of the groove will deteriorate significantly, and if trimming is continued without noticing, a large number of defective products will be produced.

(7) If the disc-shaped grindstone wears beyond a certain level or becomes clogged, it needs to be dressed or replaced, and at that time, detailed adjustments are required, which limits the ability to increase productivity.

(8) Since only one film resistor gripped by a chuck can be trimmed using one disc-shaped grindstone, the number of products produced per unit time is small.

(9) In order to perform good trimming, set the rotating surface of the disc-shaped grindstone so that it forms an angle θ along the spiral groove with respect to the film resistor, as shown in Figure 9. The inclination of the film resistor with respect to the axial direction must be finely adjusted while trimming, which requires a skilled worker, and if the adjustment is insufficient, the condition of the trimmed groove may change. Not only will this deteriorate, but the life of the disc-shaped grinding wheel will also be shortened.

Further, the problems of a trimming device using a laser beam and a resistor trimmed with the same will be described below using a general Q-switching YAG laser trimming device as an example.

α [When trimming a resistive film with a laser beam, it is important for quality control that no resistive film remains in the spiral-shaped part where the film is removed, and current linearity is usually evaluated as a substitute characteristic. necessary and involves complicated preparation work.

Although the throughput per unit time of this device using αυ laser light is at most several times that of the device using the disk-shaped grindstone mentioned above, the device itself and repair parts are extremely expensive, so there is no added value. It is hardly profitable for products other than high-quality products.

Therefore, in order to solve the above-mentioned problems, the present invention uses a thread-like abrasive thread with little change over time as an abrasive material, and by scraping off only the resistance film, the stress on the film resistor and the generated dust are reduced. The aim is to provide a trimming device that is inexpensive, highly productive, and easy to maintain.

Means for Solving the Problem In order to solve this problem, the present invention uses abrasive grains and distributes the abrasive grains inside and/or on the surface of the fibers.

It uses the abrasive thread containing the cylindrical film resistor as an abrasive material, is equipped with multiple sets of chucks that clamp both ends of the cylindrical film resistor, and is equipped with a drive device that rotates a cylindrical drum arranged around the circumference of the resistor. a mechanism for rotating a chuck held by a film resistor held by a plurality of sets of chucks, and a mechanism for causing the abrasive thread to run while being in contact with at least one of the film resistors held by the plurality of chucks, and the abrasive thread or the film resistor. The method comprises a mechanism for relatively moving at least one of the chucks holding the film resistor in the axial direction of the film resistor, and performs trimming by spirally polishing and removing the resistance film on the surface of the film resistor using abrasive grains of the polishing thread; The structure is such that the resistance value of such a film resistor is adjusted.

Function: The trimming device of the present invention uses a filament-like abrasive material to partially scrape off the resistance film, so it is possible to scrape off only a shallow portion of the surface of the film resistor, and the running speed of the abrasive thread, which is the abrasive material, can be reduced. Since a circumferential speed of about 1/1O of the conventionally used disc-shaped grindstone is sufficient, there is almost no temperature rise in the grinding part, so no thermal stress is applied to the resistor.

Furthermore, no mechanical stress such as fine cracks is left on the edges of the grooves, which prevents the electrical characteristics from deteriorating. In addition, since the object to be ground can be easily moved without leaving the surface of the film resistor, groove jumping does not occur, and the tension, running speed, and amount of pushing applied to the object to be ground can be controlled at a constant level. Ba,
Conductive conditions such as groove depth and groove width remain unchanged over time, and electrical characteristics are maintained well. Furthermore, because the grooves cut out are shallow as described above, the mechanical bending strength of the resistor body does not deteriorate, and the product will not be damaged by impact when inserted into the board with an insert machine. Since only a shallow part of the surface of the resistor is scraped, the insulator is hardly scraped, and the amount of dust on the insulator is extremely reduced. Further, since a large number of film resistors held by a large number of chucks can be adjusted simultaneously using a single thread-like grinding object, productivity per unit time can be increased. Similarly, even if the polishing thread is applied to the rotating film resistor and the polishing thread, the resistor, or both are simultaneously moved in the axial direction of the film resistor, a spiral groove can be cut in the same way. This allows for a high degree of freedom in device design. Furthermore, since a large number of film resistors are constantly being trimmed, the power of the machine is high.

Embodiment Hereinafter, a film resistor trimming device according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6.

First, a description will be given from FIG. 3, which is a perspective view showing the main components and their functions in FIG. 1, which shows a trimming unit of a trimming device according to an embodiment of the present invention.

In FIG. 3, a cylindrical film resistor 20 is inserted into a valley 2 in which the film resistor 20 is received by means of a suitable feeding device (not shown).
1 at equal intervals on the circumference,
The left chuck 2 is sent in the axial direction of the resistor by the feed cam 23
4 and a right chuck 25 supported by a spring 26, both ends of the film resistor 20 housed in the valley 21 of the disk 22 are held and rotated together with the disk 22 (angular velocity w2
), and by rotating the large gear 27 a little slower than the disk 22 (angular velocity w r ), the small gear 28 rotates (angular velocity w3), and the left chuck 24 is moved in the axial direction of the resistor by the feeding cam 23. It rotates while being fed, and the film resistor 20 held between it and the right chuck 25 is rotated while being fed in its axial direction.

Here, a large number of chucks having the same mechanism as described above are provided to continuously supply the film resistors 20.

Next, FIG. 4 to be described is an enlarged perspective view of one film resistor 20 and its surrounding area, which is being trimmed.
A groove 31 for guiding an abrasive thread 30 is provided at the peak 29 of the disk 22 which has a valley 21 for housing the film resistor 20.
is provided along which a pulley 32a in FIG.
, 32b run an abrasive thread 30 guided at the entrance and exit. The abrasive thread 30 used as an abrasive by the trimming device according to the present invention is made of, for example, nylon (trade name of DuPont), which is a polyamide-based synthetic polymer. Silicon carbide abrasive grains are added to the molten state and dispersed uniformly inside and on the surface, which is then spun and drawn to form a thread. This polishing thread 30 is supplied from a polishing thread traveling unit shown in FIG.

FIG. 5 is a configuration diagram of an abrasive thread traveling unit for supplying the abrasive thread 30 to the trimming unit 33 shown in FIG. 1 at an arbitrary thread speed and tension. In FIG. 5, the polishing thread 30 is fed from a bobbin 37 to a bobbin 38 at an arbitrary speed by a feed roller 35 driven by a motor 34 at an arbitrary circumferential speed. Nip rollers 36a and 36b function to press the polishing thread 30 so that it does not slip on the feed roller 35. Further, 39 detects the angle of the arm 42 with respect to the horizontal with a potentiometer, and when the arm 42 is horizontal, the force of the tension run of the polishing thread 30 trying to pull up the dancer pulley 40 is balanced with the force of the spring 43 trying to pull it down. Therefore, feedback control of the rotation speed of the motor 44 is performed, and the polishing thread 3
0 is supplied to the trimming unit 33 with a predetermined tension determined by the strength of the spring 43. Similarly, potentiometer 45. Arm 46. The tension dancer pulley 41 and the spring 47 detect the tension when the bobbin 48 winds up the abrasive thread 30, and feedback control the rotation speed of the motor 48, so that the abrasive thread 30 can be wound around the bobbin 38 without being cut.
It is designed so that it can be wound up.

The configuration of a trimming device which is an embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

First, a left drum 50 and a right drum 5 each house a left chuck 24 and a right chuck 25 that hold a film resistor 20 therein.
1 is positioned with a pin 61 and holds the disk 22 therebetween, and the chuck is attached to a left chuck drum 63.1 which will be assembled later. Cylindrical drum 65 along with right chuck drum 64
form.

This drum 65 is fixed to a shaft 49 with a key 62, and the shaft 49 is supported by a left base 55 and a right header 56, and is supported by a gear 52. It is rotationally driven (angular velocity W2) by a motor 54 via a gear 53.

The large gear 27 is attached to the mounting plate 58 together with the gear 57, and is further attached to the shaft 49 via bearings 59 and 59', and is rotationally driven by the motor 60 via the gear 66 that meshes with the gear 57. By making the rotational angular velocity W1 of the large gear 27, which has an angular velocity wt), slightly slower than the rotational angular velocity W2 of the drum 65, the small gear 2 attached to the left chuck 24 has a reverse rotation when viewed from the right chuck 25 side. Rotate clockwise (angular velocity W
a) Further, the steel ball 6 rolling along the feed cam 23
The left chuck 24 with numeral 7 attached to the left end is fed from left to right in the axial direction of the resistor, and the film resistor is sandwiched between the right chuck 25 supported by a spring 26 and the left chuck 24. The container 20 is fed from left to right in its axial direction while rotating as described above.

The left chuck 2 is attached to the cylindrical drum 65.
4. A total of 50 sets of chucks with the same mechanism as the right chuck 25- are stored, each with an appropriate feeding device (not shown).
The film resistors 20 supplied by the above are held one by one. Of these, 25 pairs of left chucks 24. The polishing thread 30 runs over the film resistor 20 held by the right chuck 25 while being in contact with the film resistor 20, thereby sequentially trimming the resistive film on the film resistor 30.

In the trimming device of the above embodiment, the left chuck 24 is rotated by making the rotational angular velocity W1 of the large gear 27 slightly slower than the rotational angular velocity W2 of the drum 65.
If the rotational angular velocity W1 of the drum 65 is made slightly faster than the rotational angular velocity W2 of the drum 65, the rotational direction of the left chuck 24 will be opposite to the above, but only the rotational direction of the helical groove to be trimmed will be reversed, and the rest will be the same as above. Trimming similar to the example can be performed.

Further, the trimming device of the above embodiment has a mechanism for moving the film resistor 20 held by the chuck in its axial direction, but this does not allow the polishing thread 30 or the polishing thread 30 and the film resistor 20 to be moved simultaneously relative to each other. It is also possible to configure it to be moved.

Furthermore, a resistance value measuring device is added to the trimming device of the above embodiment, and this is attached to the chuck 24 which holds the film resistor 20.
25, the film resistor 20
Trimming is performed using the abrasive thread 30 while measuring the resistance value of the abrasive thread 3.
0 may be opened from the surface of the film resistor 20.

FIG. 6 is an enlarged cross-sectional view showing the conductive state of the film resistor 20 trimmed by the trimming device of one embodiment of the present invention, in which the shallow groove 68 is trimmed and the resistor insulator 70 is trimmed.
The figure shows a state in which almost only the resistive film 69 on the surface has been scraped off.

Note that the abrasive thread 30 may have a structure in which abrasive grains are distributed and contained within the fibers and/or on the surface thereof.

Effects of the Invention The effects obtained by the film resistor trimming device according to the present invention configured as described above are as described below.

(1) It is only necessary to scrape off almost only the resistance film on the surface of the film resistor, that is, only the shallow part, using the polishing thread (thread-like grinding material), and the running speed of the polishing thread is the peripheral speed of the disc-shaped grindstone used conventionally. Since a speed of about 1/10 of that (approximately 300 m/min) is sufficient, there is almost no temperature rise in the grinding section. Therefore, no thermal stress is applied to the resistor, and no measurement error occurs when adjusting the resistance value. In addition, it does not leave mechanical stress such as fine cracks on the edge of the groove.
Due to these factors, the electrical characteristics will not deteriorate.

(2) Since the abrasive thread used in this device can be easily run without leaving the surface of the film resistor, groove jumping does not occur, and the tension, running speed, and push force applied to the abrasive thread by this device are If the amount is controlled to be constant, the conduction conditions such as groove depth and groove width will remain unchanged over time, and the electrical characteristics of the product will be maintained in good condition.

(3) In order to adjust the resistance value of a film resistor, it is only necessary to scrape away the portion of the resistor surface where the resistance film exists (several μm thick), but the polishing thread used in this device is capable of grinding shallow grooves. As mentioned above, it is easy.

Because the grooves cut out in this way are shallow, the mechanical bending strength of the resistor body does not deteriorate, and the product will not be damaged by impact when inserted into the board with an insert machine. Since only a shallow part of the resistor is ground, the resistor insulator is hardly ground, and as a result, the amount of dust generated on the insulator is extremely small.

(4) This device can apply new parts to the resistor surface one after another by running the abrasive thread, so the grinding force of the abrasive thread remains unchanged over time and the conduction state does not deteriorate.

(5) As shown in Figure 6, the edges of the grooves do not become sharp, so they are less likely to damage other resistors and the edges of the grooves themselves are less likely to chip, resulting in deterioration of the resistor's electrical characteristics. can be prevented.

(6) With this device, even if the film resistor fails to be inserted into the chuck and the film resistor rotates eccentrically, the polishing thread can move freely according to the movement of the film resistor, so the polishing thread will not be damaged. There's nothing to do.

(7) This device is capable of scraping only the shallow part of the surface of the insulator, so there is little wear on the polishing thread, and when replacing it, you only need to replace the polishing thread, and there is no need for detailed adjustments. (5).

In combination with point (6), productivity can be increased.

(8) The resistance values of a large number of film resistors held by a large number of chucks can be adjusted simultaneously with one polishing thread, resulting in high productivity.

(9) Even if one or both of the polishing thread and the film resistor are simultaneously moved in the axial direction of the film resistor while applying the polishing thread to the rotating film resistor, the same spiral groove will be formed. This allows for a high degree of freedom in equipment design, and the adjustment required to set the abrasive thread at an angle θ along the spiral groove with respect to the film resistor is different from that of conventional cutting wheels. It is much easier than other methods, and even non-skilled workers can easily cut a good groove.

Compared to a trimming device that uses OQ laser light, the equipment cost is low, maintenance work is easy and no skill is required, and the operating cost is low along with high productivity.

Ql) In the conventional trimming device, the disc-shaped grinding wheel mechanism stands by while the film resistors are being fed to the chuck, and no trimming is performed. However, in the trimming device according to the present invention, a large number of film resistors are always fed into the chuck. Since the machine is trimming, the work rate of the machine is high.

Since the film resistors to be trimmed at the same time are arranged around the circumference of the drum and the polishing thread is wound around them, by controlling the tension of the supplied polishing thread at a constant level, each film resistor can be polished. Since the force that presses the thread can be kept constant, conditions such as the depth of the grooves in the many trimmed film resistors can also be kept constant.

[Brief explanation of drawings]

FIG. 1 is a front sectional view showing the configuration of a trimming unit of a trimming device according to an embodiment of the present invention, and FIG.
FIG. 3 is a plan sectional view showing the drive mechanism of the large gear that drives the chuck in the device shown in the figure; FIG. 3 is a perspective view showing the main components of the trimming unit of the trimming device according to an embodiment of the present invention and their functions; The figure is an enlarged perspective view of the film resistor and its surrounding area being trimmed by the trimming device shown in FIG. 1, and FIG. FIG. 6 is an enlarged sectional view showing the conduction state of a film resistor trimmed by a trimming device according to an embodiment of the present invention, and FIG. 7 is a diagram showing a disc-shaped grinding wheel according to a conventional technique. FIG. 8 is a perspective view of the trimming device used. FIG. 8 is a diagram showing an example of a mechanism for applying a disk-shaped grindstone to a film resistor in the trimming device shown in FIG. 7. FIG. 9 is a perspective view of the trimming device shown in FIG. FIG. 10 is an enlarged sectional view showing the conductive state of the film resistor trimmed by the apparatus of FIG. 7. FIG. 20... Cylindrical film resistor, 22...
Disc, 23... Feed cam, 24...
・Left chuck, 25...Right chuck, 26...
...Spring, 27...Large gear, 28...
... Small gear, 30 ... Polishing thread, 32a, 32b
... Pulley, 33 ... Trimming unit, 65 ... Cylindrical drum. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 2 Figure 4 Figure 5 Figure 8 Figure 9

Claims (1)

[Claims] A cylindrical cylinder in which an abrasive thread containing abrasive grains distributed and contained inside and/or on the fiber is used as an abrasive material, and is equipped with a large number of chucks for holding both ends of a cylindrical film resistor, and these are arranged on the circumference. The polishing thread is provided with a drive device that rotationally drives the shaped drum, and further includes a mechanism that rotates a chuck holding each film resistor, and brings the polishing thread into contact with at least one of the film resistors held between the multiple sets of chucks. and a mechanism that moves at least one of the abrasive thread or a chuck holding the film resistor in relative motion in the axial direction of the film resistor. A resistor trimming device configured to perform trimming by removing a resistive film in a spiral pattern to adjust the resistance value of such a film resistor.