DE2141659A1 - Device for cutting electrical resistors - Google Patents

Description

"Device for cutting electrical resistance"

The present invention relates to abrasive cutting tools and, more particularly, to an abrasive cutting tool which that uses an extremely fine abrasive powder to precisely cut electrical To cause resistance.

In devices for ejecting abrasive powder according to the In the prior art, a mixture of the abrasion powder with compressed air is used, the compressed air being the abrasion powder brings to a nozzle from which the air charged with abrasive powder in the form of an abrasive cutting jet at high speed is expelled. Abrasion cutting tools this one

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Art are used for many precision work, such as » for surface treatment, for trimming, for removing surface coatings, for cutting electrical ones Resistances and other work.

In the manufacture of electrical equipments that are required to perform many functions, a great deal of complicated becomes Circuits and circuits used to effect the desired functions. Circuits under Using conventional conductive wires, resistors, conductors and capacitors are required for forming Manufacture of complex circuits takes up considerable space, in the case of electrical equipment intended to be used in a Carrying out a large number of functions, such as computers, has in recent years been aimed at developing Make circuits that can perform the same number of functions but are much smaller, to avoid such circuits being excessively large will.

In recent years, one type of space saving circuit arrangement is came on the market, commonly referred to as electronic microcircuit. The one on the Circuit parts and circuits formed in the field of electronic microcircuits are extremely small and are usually stamped on a thin circuit board. Within a single circuit board of about 50 χ 50 mm in size, it is not uncommon to have several a hundred different electrical conduction strips are formed thereon.

It is of the utmost importance to accurately measure the electrical resistance of each individual circuit on the circuit board determine. In the past, this has proven to be extraordinary

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proved to be difficult. The simplest method of achieving such a change in resistance has been to cut each of the conductive strips by reducing the width of the strip, which automatically reduces the conductive area. One possibility for this is to connect an ohmmeter to a circuit with the conductive strip and to reduce the width of the strip until the desired resistance value of the strip is measured by the measuring device. However, in order to perform such a procedure by hand, it is normally not possible for a human to cut a conductive strip precisely by the amount required to achieve the level of precision required. Furthermore, such a process becomes extremely tedious since a large number of circuit boards usually have to be cut.

In an attempt to produce a large number of panels, each of which contains the same circuits, and each having conductive strips within each circuit board accurately measured electrical resistance, it has been customary to provide an automatic cut to size M device to use. The heretofore known such automatic trimmers normally act to move the abrasive cutting nozzle into the circuit board and into the particular conductive strip whose electrical resistance is to be reduced. It is common practice to use an electrical bridge balancer which measures electrical resistance and then automatically turns off the trimmer when a desired resistance as measured by the electrical bridge has been achieved.

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Although such a device is completely independent of the manual skills of the operator for cutting it has been found to be inexpedient. For example, it was found that during the short Length of time that the bridge is balanced and indicates that the desired electrical resistance has been achieved and in which the device is switched off, the cutting effect is still reduced by a small amount which leads to a certain inaccuracy. Such automatic trimmers are also typically considerably complicated in their training and therefore very expensive to manufacture. Furthermore, it was not possible to do such to move automatic devices quickly into or out of a working position and at the same time extremely fine Allow partial movements of the conductive strip in direct alignment with the cutting nozzle. Normally such automatic cutting devices change the speed of the drive motor that drives the cutting nozzle or theirs Causes movement. With such a change in the speed of the drive motor, however, it is not possible, exceptionally make fine adjustments with regard to the partial movements.

In the cutting device according to the present invention the circuit board is in and out of alignment to achieve an extremely accurate trimming process moved to an immovably arranged cutting nozzle. An operator optically determines the extent of the cutting process and moves the circuit board out of the Alignment with the cutting nozzle. As a result of the use of one operator, the degree of accuracy becomes much greater achieved than was previously possible. The circuit board is moved in very fine increments as it moves

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close to the cutting nozzle. The circuit board is also moved in significantly larger partial movements when it is moved a short distance away from the cutting nozzle.

The trimmer according to the present invention is used a rigidly arranged head to which a nozzle is attached through which an abrasive cutting powder is passed will. An electronic microcircuit is built on a f

Intermediate pad rigidly attached, the opposite of a rigid pad towards the cutting nozzle and away from it is movable. The intermediate pad is opposite the rigid pad by hand via a linkage arrangement moveable. The linkage arrangement allows the circuit board to move at a variable speed with respect to one another the cutting nozzle, namely movement over longer distances when the circuit board is not in the immediate vicinity Near the cutting nozzle and extremely small partial movements when the circuit board is close located on the cutting nozzle. A probe assembly is positioned near the circuit board and is adjustable so as to j that an electrical connection with a special elec- ' trically conductive strip is made on the circuit board. The probe assembly can be moved away from the circuit board when the circuit board is moving is in the furthest position from the cutting nozzle. A balancing bridge measuring arrangement is electrical connected to the probe assembly.

In the drawings, in which a preferred embodiment of the invention is illustrated, are

1 is a front view of the cutting device according to the present invention;

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FIG. 2 is a view of the cutting device shown in FIG from the right;

3 shows a plan view, partially shown in section, of the cutting device according to the invention the line 3-3 in Figure 2;

4 shows a sectional view of the cutting device according to the invention along line 4-4 in Figure 3;

Fig. 5 is a bottom view partially shown in section along the line 5-5 in Fig. 2, in which the invention the linkage arrangement used is shown in more detail; and

6 shows a sectional view along the line 6-6 in FIG. 5 in the parts of the linkage arrangement according to FIG of the present invention in more detail are shown.

In the drawings, to which reference is now made, is in Fig. 1 the device 10 according to the present invention shown. It consists of a rigid lower part 12, an intermediate lower part 14, a head part 16 and a rear part Part 18. A nozzle 20 is rigidly mounted in the head part i6 and serves to generate abrasive particles in the form of fine particles along with compressed air from a source (not shown) submit. The head part 16 is rotatably attached to the rear part 18 by means of a pivot pin. The headboard 16 has a hollow central chamber 24, the function of which is described in more detail below. A sleeve is on the outside around the head part 16 in the area of the pivot pin rigidly attached. A first eyelet 28 and a second eyelet 30 are attached to the sleeve 26. The first eyelet 28 is opposite

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of the second eyelet 30 on the opposite side of the sleeve 26. A nut 32 is held rigidly in an opening in the first eyelet 28. The nut 32 cooperates with a threaded bolt Jk which extends from the rear part 18 through an opening 36 to the outside. A rounded head 38 formed on the threaded bolt 34 prevents the bolt 34 from being separated from the opening 36. A knurled knob 40 is attached to the rounded head 38 and allows the bolt 34 to be rotated by hand. A compression spring 42 is attached between the rear part 18 and the first eyelet 28. It should be noted that when the bolt 34 rotates, the head 16 rotates around the pivot 22 relative to the rear part 18.

The second eyelet 30 acts as a guide for a bolt 44 which is screwed into a third eyelet 46. The third eyelet 46 is rigidly attached to the head 16. A part of the bolt 44 extends from the rear part 18 to the outside through a slot 48. A knurled knob 50 is attached to the bolt 44, and prevents the separation of the μ bolt 44 from the slot 48 in the rear part 18. The puncture of the Bolts 44 and 34 are to allow angular adjustment of the head 16 relative to the rear portion 18, as will be described in more detail below.

A negative pressure from a source (not shown) is introduced into chamber 24 via line 52. The negative pressure serves to remove the particles of abrasive material that have been sent through the nozzle 20 in order to avoid that the particles get to the outside air and a Form a layer of dust on the device 10.

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The intermediate lower part 14 comprises a main support plate 54; to which a front plate 56 and a rear plate 58 are attached. Side panels 60 are also secured between the front panel 56 and the rear panel 58 on the sides of the main support panel 54, thereby defining a substantially closed chamber 62. Between the front plate 56 and the rear plate 58, two rods 64 and 66 located at a distance from one another are rigidly attached. The rod 6k cooperates with a guide device 68, while the rod 66 cooperates in a similar manner with a guide device 70. Each of the guide devices 68 and 70 is rigidly attached to the rigid lower part 12. Furthermore, the two guide devices 68 and 70 are of the same design and include bearings 72 in order to bring about an extremely precise longitudinal movement of the intermediate lower part Ik with respect to the rigid lower part 12.

A rod 76 is rigidly attached to the front plate 56 by a set screw Tk. The rod 76 extends through a slot 78 which is formed in the rigid lower part 12 and is attached to a block 80 which can be displaced to a limited extent in a groove 82 of a forked arm 84. The free end of the forked arm 84 is hinged to a plate 88 by a pivot 86. The plate 88 is hinged to the rigid base 12 by a pivot 90. A link arm 94 is rotatably mounted between the ends of the forked arm 84 by a pivot 92. An actuator arm 96 is hinged to the free end of the link arm 94 by a pivot 98 and is further hinged to the plate 88 by a pivot 100. The actuating arm 96 extends through a slot 102 which is formed in the rigid lower part 12. An extended rotary knob 104 is rigidly attached to the free end of the actuation

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_ 9 arms 96 attached.

The intermediate lower part 14 further comprises a lower housing 106 and an upper housing 108. The housing 106 is rigidly attached to the main support plate 5 ^. The upper case 108 is attached to the lower housing 106, and a platform 110 is attached to the upper housing 108. the Platform 110 is movable with respect to the upper housing 108 by means of a device (not shown). which causes this movement is known in the art and need not be described in detail here. A Adjustment knob 112 is provided through upper housing 108 to enable said adjustment to be made.

A circuit board 114 is supported by holding means (not shown) to be rigidly attached to the platform 110. The circuit board 114 is also of known design and has a plurality of electrically conductive strips (not shown) formed thereon.

A first and a second flange plate 118 and 120 are relative to the lower housing IO6 ^ by means of a shaft II6 rotatably attached. A weight I66 is over a rigid shaft ' 168 attached to the flange plate 118. A support plate 122 is attached to the upper surface of the flange plate 118 and Similarly, a support plate 124 is attached to the upper edge of the flange plate 120. On the support plate 122 A pivot 126 is rotatably mounted and a pivot 128 is rotatably mounted on the support plate 124. A Bolt 130 is screwed into pivot 126. Similarly, a bolt 132 is screwed into the pivot 128. A knurled knob 134 is attached to the bolt 130 and a knurled knob I36 is on attached to the bolt 132. A probe 138 is on the bolt

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130 attached at its free end and in a similar manner a probe 140 is connected to the bolt 132 at its free end. Each of the probes 138 and 140 is capable of after an electrically conductive element has been placed therebetween, an electrical circuit through the conductive strips (not shown) of the circuit board 114 to manufacture. The resistance of the conductive strips can be read from the meter 142. Between Probes 138 and 140 and meter 142 is a known one electrical bridge circuit, commonly referred to as a trim bridge, is provided. This bridge scarf device can be adjusted so that when a special electrical resistor is attached between the Probes 138 and 140, the meter 142 will display a numerical value of zero, indicating that there is an ab- equation of the circuit has been achieved.

On the shaft II6 is the interior of the lower housing 106 a stop 144 attached. A bumper 146 extends through an opening in the main support plate 5 ^ and in contact with the stop 144. A stop disk 148 is attached to the bumper 146 by the amount of downward movement the bumper 146 limit. A second washer 150 is attached to the bumper 146, and a spring 152 is between the disc 150 and the main support plate 5 ^ arranged. The spring 152 strives to the bumper 146 to hold in the lower position in which the stop disk 148 rests on the main support plate 54.

The free end of the bumper 146 can be in contact with the front end of a pivot arm 154 are brought. The arm 154 is attached to the rigid base by a pivot 156 12 rotatably attached. The rear end of the pivot arm is provided with a cam surface 158. A pestle

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is in constant contact with the curved surface 158. The The plunger 160 is attached to a piston I62, which in turn is rigidly connected to the lower part 12. The operation of the piston i62 is caused by a switching device (not shown), which can be selected from the Operator is operated.

The mode of operation of the device according to the invention is as follows: When the intermediate lower part 14 is displaced into the position furthest away from the rear part 18, the plunger 160 is moved up the cam surface 158, as a result of which the swivel arm 154 is swiveled against the push rod 146. The spring 142 is compressed and the shaft 116 is rotated due to the force exerted on the stop 144 by the push rod 146. The probes 138 and 140, which are connected to the shaft II6, are thereby caused to assume a position displaced from the platform IiO, as is shown in FIG. 6. This location allows a circuit board 114 to be attached to the platform 110 by an operator. The operator then grips the extended rotary knob 104 of the actuating arm 96 and bewijfcfc the movement of the arm 96. The M probes 138 and 140 then fall due to the force of gravity onto the circuit board 114. A positive electrical contact is ensured by the weight I66. During movement of arm 96 by distance A (FIG. 5), the particular conductive strip on circuit board 114 to be cut by the device is moved in close proximity to nozzle 20. The forked arm 84 has been pivoted so far that it abuts the plate 88. The position of the nozzle 20 has been previously determined by turning the knobs 40 and 50, which in turn cause the bolts 34 and 44 to rotate. By turning the bolt 34 in one direction, the head l6, which the nozzle 20 contains, is

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holds, rotated counterclockwise in the view of FIG. By rotating the bolt 34 in the opposite direction, the head 16 is rotated clockwise. Of the Bolt 44 enables the longitudinal adjustment of the head l6 compared to the rear part 18 of the device.

When the special conductive strip of the circuit board 114 has been brought into close proximity to the nozzle 20, the operator then moves the button 104 the distance B, (Fig. 5). The operator may or may not move button 104 the entire distance B. Be it notes that B is larger than A. However, since the forked arm 84 abuts the plate 88, the Plate 88 to rotate about pivot 90. Since the rod 76, which causes movement of the intermediate lower part 14, only a relatively short distance from pivot 90 is removed, the intermediate lower part 14 moves only a very short distance, although the distance B is quite large is. When the forked arm 84 comes into contact with the plate 88, a microswitch (not shown) is also activated actuated, by the switching action of the powdery abrasive material is sent through the nozzle 20 and the negative pressure is caused in the chamber 24. When the operator moves button 104 over distance B, it calls through Powdered abrasive sent to the nozzle 20 reduces the width of a particular conductive strip on the circuit board 114. Probes 138 and 140, each at one end of the particular conductive strip cause an electrical circuit to be established in the particular conductive strip. This electric Circuit is part of a leveling bridge that essentially determines the electrical resistance of the conductive strip compares and optically displays the measured comparison on the measuring device 142. When the particular guiding strip—

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sufficiently tailored to the desired resistance value is, the meter 142 displays a value of zero, which indicates to the operator that the desired resistance value has been achieved. The operator then pulls back button 104, thereby removing circuit board 114 from nozzle 20. Note that the spring 164 supports this movement in that it tends to move the plate 88 in the direction of the continuous in FIG. 5 Panning the position shown in the lines. When the f operator presses button 104 further along the route A moved back, when the forked arm 84 is moved out of contact with the plate 88, becomes a microswitch (not shown) switched off, in turn the powdery abrasive material passing through the nozzle 20 switches off and also switches off the negative pressure in the chamber 24. When the button 104 is the furthest back Position reached, the probes 138 and 140 by actuating a switch (not shown) by the operator upwards and from the circuit board 114 " swung away. The operator can then easily remove the cut circuit board 114 from platform j Remove 110 and replace it with a corresponding circuit board 114 that has not yet been cut to size. The one described above The process is then repeated for the uncut circuit board 114.

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Claims (8)

2H1659 - lh - PATENT CLAIMS: 1. / Device for cutting electrical resistors, characterized by a first device with the one Reduction of the cross-sectional area of an electrical resistor is caused, a second device, in the middle of which the electrical resistance is immovably arranged, a third device by means of which a constant measurement of the electrical resistance value of the electrical resistance is carried out, and a fourth Device that controls the movement of the electrical resistor to and from the first device effected away, wherein the fourth device comprises a structure acting at a variable speed. 2. Apparatus according to claim 1, characterized in that the structure acting at a variable speed comprises an operating arm which is movable by an operating force and which is so arranged and connected is that it causes actuation of a first link arm and a second link arm, the first link arm is movable against the second linkage arm and the electrical resistance by a first distance in Direction to the first device causes and the second link arm subsequent to the termination of the movement of the first rod arm is movable to see the £ lektrisehen Resistance to move a second distance toward the first device, the second distance being substantial is smaller than the first route. 209809/1206 -15- 2H1659 - 15 - 3. Apparatus according to claim 2, characterized in that the actuating arm during the movement of the first linkage arm is movable over the first distance over a third distance and during the movement of the second linkage arm over the second distance can be moved over a fourth distance, the fourth distance being greater than the third distance. k. Apparatus according to claim 1, characterized in that the third means comprises a probe arrangement in electrical "contact with the electrical resistance and effects the establishment of an electrical circuit for measuring the electrical resistance value of the resistance, and in that a device for optically displaying the electrical resistance is provided . 5. Apparatus according to claim k, characterized in that the probe arrangement is movable between a conductive position and a non-conductive position, the conductive position being in the immediate vicinity of the second device, while the non-conductive position is remote from the second device. λ 6. Apparatus according to claim 1, characterized in that the electrical resistance consists of an electrically conductive Strip on an electrical circuit board is. 7. Apparatus according to claim 1, characterized in that the first device is one on a stationary structure Attached head comprises which is pivotable relative to the fixed structure, and that attached to the head a nozzle through which a powdery abrasive substance can be sent and that a holding device is provided, by means of which the head in relation to the fixed structure can be arranged rigidly. 2 0 98097 120 6 - 16 - 8. Apparatus according to claim 7 »characterized in that the head has an inner chamber in which a negative pressure can be caused so that the negative pressure removes the spent powdery abrasive. 209809/1206