JPS63212427A - Demagnetizing device and method - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] The best skin appearance! The present invention relates to the field of demagnetization of parts that have already been magnetized and will be used in the future. For the purpose of using
These must be demagnetized, whether they are intentionally or accidentally magnetized, the functionality of the device of the invention is equivalent, but most of the field of demagnetization technology is directed to intentionally magnetized workpieces. It has been developed to such a high level that it The most obvious example of such a situation is a grinding machine or grinder where the workpiece is held by a magnetic chuck. The workpiece held in this way is deliberately magnetized as described above,
After being ground, the magnetic force is cut off. Residual magnetism remains on both the workpiece and the chuck, and it is necessary to use a degaussing device to remove such residual magnetism.

This general field has been very highly developed, and developments to date include various states or modes of control of the magnetic holding force that holds the workpiece on the chuck, as well as Contains the later demagnetization state.

In such different states or modes, the complete (Ftl
LL), variable (VARIABL!ri), and residual (R
Various levels of retention force are used, including the level known as H3IDUAL). Each of these states has a specific purpose, but is of course used individually;
None of the conditions are used together, requiring good control of this holding force to its different levels during the entire grinding procedure. A fourth mode, R[!LEASE, is also used to demagnetize the workpiece and release it from the holding force.

Conventionally, in such demagnetization work, it has not been possible to control the holding force as described above well to various levels.

When applying the invention to a grinder, the device of the invention not only controls the demagnetization but also completely controls the chuck, so that the device can also be called a chuck control device. However, it can also be applied to other stages of demagnetization.

A general object of the present invention is to provide a novel apparatus and method for adjusting and establishing the control sequence of workpiece retention and degaussing in chuck control operations.

A more particular object of the invention is to provide such an apparatus and method that is particularly applicable to grinders in which various states of magnetic coercion are used.

Such devices and methods include the following features and advantages.

1. A new and effective safety feature is provided in the form of an ink lock to prevent accidental shifting of the chuck control from one state of holding force to another.

2. Such a device and method simplifies the control of the holding force, ie the operation of holding the workpiece in the grinder, and thus speeds up the grinding-related operations.

3. Such a device includes a novel indicator indicating the stage of the operation (grinding) being controlled and the function of its various stages.

4. Such a device is adapted to be integrated into the integrated electrical control unit normally provided in the machine in which it is used, for example a grinder.

Implementation ■ To facilitate consideration of the characteristics of the present invention, it will be stated that the demagnetization action always accompanies its own magnetization. As mentioned above, when the degaussing device is applied to a grinder where the workpiece is held on a table by a magnetic chuck, both the chuck and the workpiece are of course magnetized. When you want to remove the workpiece,
The holding magnetic force is turned off, but the residual magnetism in question is usually very large and must be removed in order to remove the workpiece from the chuck. This is done with a demagnetization step in which the workpiece is repeatedly magnetized. That is, the workpiece is magnetized in successive steps in opposite directions, i.e., with opposite polarities, and in each step the voltage is decreased, and in the last step and in the opposite direction, the magnetism is at or near zero. Become. This degaussing action thus includes these magnetization steps, and the entire magnetization step is controlled and implemented by such a demagnetization device or chuck control according to the invention.

In the industry, MAG and ? The term IAGGING is understood to mean "magnetize" and "magnetize," respectively, and similarly refers to DEMAG and [lEMAGG
The term ING means "demagnetize" and "demagnetize."

At various stages of the grinding operation, different levels of magnetic force are used to hold the workpiece in place on the grinder. These steps are highly developed in conjunction with the development of degaussing devices, and are in fact made possible by the advanced development of degaussing devices. Of course, in a grinding operation, the workpiece must be held securely in place, and the FULL setting provides the large holding force necessary for actual grinding. This perfect (PtlLL) level can have different values in different different grinding operations, but in any grinding operation it is set at a predetermined value and is never exceeded.

In a variety of different grinding operations, variable (VARIA[1LE) stages are used to hold workpieces with different characteristics. Some workpieces often have to be held with less force due to their properties, such as their shape or low strength. These different types of workpieces are held according to their characteristics in each individual grinding operation, but may differ in successive grinding operations. For example, if a workpiece is hollow and placed on a grinder with its concave side down, large holding forces applied may distort or even puncture the workpiece. , In such cases, as in many other cases, small holding forces are used that do not distort the workpiece. In such cases, it is necessary to use a smaller grinding force,
This is acceptable due to the requirement that no distortion be introduced.

The device performs a
It has the characteristic that it can be selectively set to a different value (VARIABLE).

At another stage of the grinding operation, one workpiece is removed from the chuck for the purpose of inspecting the grinding before it is completely ground, and it is placed again to continue the grinding operation. It may be necessary to place the

At this stage, only this one workpiece is removed, no other workpieces are removed, and the holding force is reduced to residual (RI!S r[1UAL) to remove this workpiece. This residual (RESTDtlAL) force is sufficient to hold these workpieces in their original position without the application of external forces. Once this inspection step has been carried out, the workpiece is repositioned and the equipment is then placed again in its full or variable setting and the grinding operation continues.

Once this complete grinding operation is complete, the device is released (RE).
LEASE), and in response, a degaussing operation is performed. This step has been mentioned elsewhere and need not be discussed in detail here, but the net effect is to reduce the holding force to zero or near zero to release the workpiece from the chuck.

The present disclosure generally describes the apparatus according to the present invention as applied to Cross Reference II (U.S. Application No. 571,387, 1
(filed on January 17, 1984). For convenience, this cross-referenced application will be referred to as the prior publication and its degaussing device will be referred to as the base device. Due to the interaction of the control device of the present invention with specific details of the basic device, prior art devices are cited herein. Regarding the correlation of corresponding parts of such electrical circuits in these two applications,
FIG. 3 according to the present invention includes the contents of FIG. 3 in the basic application, but in the present invention an additional current sensing unit is placed at the bottom right of FIG.

4 and 5 of the present invention are collectively referred to as
It contains the contents of Fig. 5 and Fig. 5, respectively.

6 and 7 contain an apparatus according to the invention.

Wherever possible, the same reference numerals have been used in the invention as in the earlier application for identical elements and parts.

The drawings will be explained in detail. FIG. 1 shows a grinder 12 of the known type, which has a table 14 that reciprocates horizontally and vertically as indicated by the double-headed arrow 16, and which has the reference numeral 14. The unprocessed workpiece, indicated at 18, is placed on this platform and held thereon by a magnetic chuck 20 embedded within the platform. A grinding wheel 22 operates within the vertical slot 24 and is lowered into working engagement with the workpiece to perform the grinding operation as the workpiece is reciprocated thereunder by the platform.

The circuit diagram will be explained. FIG. 2 shows the arrangement of the chuck 20 and the workpiece 1 in the vicinity of FIGS. 3 to 7.
It will be noted that 8 is seen at the bottom of FIG.

For convenience in considering the different parts of this circuit in these different diagrams, reference will be made to the dashed lines cutting parts of the circuit, and the conductors of the circuit that are cut by these dashed lines are , are identified on opposite sides of these cutting lines, which makes their alignment easier. The parts of each conductor that are cut are given the same reference numerals on the opposite side of the cutting line, and these reference numerals are used throughout the subsequent description of the electrical circuit.

A vertical cutting line 7 separates FIGS. 3 and 6, and the conductors cut by this cutting line are designated by reference numerals 7a-
7c. A vertical line 8 separates FIGS. 4 and 5, and the conductors cut by this vertical line are individually identified by reference numerals 8a-8b. A vertical line 9 separates FIGS. 6 and 7, and the conductors cut by this vertical line are designated by the reference numeral 9a.
-9h. A horizontal line 10 separates FIGS. 4 and 6, and the conductors cut by this horizontal line are individually identified by reference numerals 10a-10d, and conductor 10e also separates FIGS. 5 and 6. is identified by A horizontal line 11 separates FIG. 5 and FIG. 7, and the state cut by this horizontal line is as follows:
Individually identified by reference numerals 11a-116.

This circuit includes a power circuit 26 in FIG. 3 and a control circuit 28 in FIGS. 4-7. The circuit includes an AC power source 30 leading to a power transformer 32 and conductors 34, 36, 38, 4 leading from the power transformer to chuck 20.
Contains 0.

This power circuit 26 includes the secondary of a particular magnetizing transformer, the entirety of which is included in FIG.

Each transformer includes one primary and two secondary sides, each referred to as a set, an ONN cellar 50 and a DEMAG set 52, respectively. Regarding the identification of these transformers, their secondary sides are identified by the same main reference numerals with a postscript P, and their secondary sides are also identified by
Identified by the same main reference numerals with the suffix S and additional suffixes 1 and 2. These transformers are power transformers 32
and is operatively associated with the SCRs 56, 58 (FIG. 3).

SCRs 56 are individually identified as 56^, 56B, and are each associated with secondary side 50S, as well as SCR 58, individually identified as 58A.

58B and are each operatively associated with secondary side 52S. Secondary side 50S, as explained below.

When the 52S is energized, these secondary sides are connected to the SCR56,5
8 to control the current flowing from the power transformer 32 to the chuck 20. Transformer set 50 is used to hold the workpiece on the chuck during the grinding operation, and both sets are used to perform the degaussing operation.

These SCRs, ) transistors, rectifiers, triacs, and gates may be collectively referred to as valves.

The control circuits shown in FIGS. 4 and 5 will be explained.

A main or control transformer 60 exits the AC power supply 30. The control circuit 28 (bottom of FIGS. 6-7) also includes switch means 62, which switch means 62 comprises four individual switches 62A RELEASE , 62
BRESIDUAL, 62CVAl? IABLE, and 621) FULL, and the power circuit also includes a potentiometer 64 (bottom right in FIG. 7) having an arm 65. These individual switches 628, 62B, 62C, 62D are indicated by the names associated with them in the function of the various stages in the grinding operation and the subsequent control operations associated therewith, including demagnetization and partial demagnetization. individually and manually according to the functions implemented as indicated and as indicated above.

A full-wave bridge rectifier 70,72 (FIG. 4) emerges from the secondary side 60S, the former leading to a trigger circuit 74 and the latter leading to a DC regulator 76. A dot bar driver 78 (FIG. 5) of known type is included in the control circuit, and this driver 78 has an input pin 80 in a reference position.
(15) and a series of pins 82 (+110-118) and pins 84 (11). Pin 11 is connected to resistor 86
and the other pin is connected to control a resistor 88 which is connected to a common conductor 90 which is
It reaches the conductor 8d.

Conductor 8a is a common conductor that appears in all of Figures 4 to 7, ie from Figure 4 (top right) it runs to the left and then to the bottom. From this position in FIG. 4, it goes to the right in FIG. 5, then to the bottom, then to the bottom in FIG. 7, and then to the left. And it reaches the left side of Figure 6.

Potentiometer 64 (bottom right of FIG. 7) is connected at its LO end, designated by reference numeral 91, to conductor 9j and to common conductor 8a, and its LO end, designated by reference numeral 93, It is connected to the conductor 91 at the HT end. When operating the grinder as well as the device according to the invention, the operator initially uses the AC power source 30
Close the switch (FIG. 3) and then actuate the switch means 62 (bottom of FIGS. 6-7) according to the desired mode. For FtlLL mode, the operator closes switch 62D (FIG. 7), which causes pin #12 of flip-flop chip 94 (middle left in FIG. 7) to go LO.
leading to. At this time, transistor 95 is turned on, and conductor 95', digital switch 96. Conductor 96', digital switch 97, which is closed at this point. It passes through the conductor 11b and reaches the conductor 97' (FIG. 5) and the driver 78,
Apply a positive voltage to pin I5 of this driver. This voltage is DC and has a value of approximately 12 volts DC determined by voltage regulator 76. This allows pins 4 and 7 at tips 96'' and 96° (middle in Figure 5) to
．． 13.14 as well as pin I4 of chip 97''. At the same time, the III signal is applied to complementary output pins 3.9, 12.14 of chips 962 and 96'°.
15 and appears at pin I3 of chip 97. This H1 signal is applied to the bases of chips 97a and 97b and to transistor 98'.

These chips 96", 96'"°, 97", 97a
, 97b has four NPN) transistors built into each chip. As just mentioned, when the I11 signal is applied to these bases, 97a, 9
The transistors at 7b and 98° are turned on. This results in a resistance of 86°88. and 981 are applied to the circuit, and capacitor 103 (FIG. 4) charges at its maximum rate to provide maximum DC output to ON transformer set 50.

Conductor 97' includes a capacitor 98 (top of FIG. 5) that connects potentiometer 64 (seventh
(Fig. (right) and in parallel with transistor 100 (top of FIG. 5) in unit 99. Capacitor 98 and unit 99 provide linear damping during the demagnetization phase.

In operation of driver 78, resistors 86, 88 and 98 actually
” are placed in the circuit. This is due to an internal function according to its characteristics of the driver. When no voltage is applied to pin 115, none of these resistances are placed in the circuit and selectively increased When a level voltage is applied, the number of these resistors placed in the circuit becomes larger and therefore the output voltage also becomes larger.The circuit thus established through the driver 7 days has a DC output applied to the magnetic chuck. It has the function of controlling voltage.

A voltage of appropriate value, in this case 12 volts, is applied to the transformer 6.
0 (top of FIG. 4) through the rectifier 72 to the terminals 91.93 of the potentiometer 64 (bottom right of FIG. is transmitted to driver 78. Depending on the number of resistors 88 that are turned on according to the applied predetermined voltage, the corresponding output voltage will be applied to the capacitor 103 (upper middle of FIG. 4) at the output conductor 90 (8d) (upper middle of FIG. 5). is applied to A zero-crossing detector 104 (fourth top left) containing transistors 105, 106 turns on transistor 108 each time unit 104 crosses zero. This discharges capacitor 103 and begins a phase timing sequence or delay.

This phase delay is achieved by an RC time constant determined by the capacitor values and the number of resistors 86 and 88 turned on by unit 78. capacitor 10
3 is associated with a transistor unit 110,
The transistor unit 110 includes transistors 112 .
114, the voltage across capacitor 103 is monitored by transistor 114, and when the voltage on capacitor 103 exceeds a reference voltage set by transistor 112, transistor 114 is turned on. R1! In the LEASE cycle, capacitor 1
The DC output is determined by the attenuation of the voltage at 03;
On the other hand, the capacitor decay of 9 days determines the total time of the degaussing cycle. These transistors 1
12.114 is configured such that changes in voltage across transistor 114 caused by temperature changes are compensated for by similar changes in transistor 112.

Another transistor 116 buffers the output from unit 110, which is then differentiated by capacitor 118, by adjusting the value of capacitor 118.
The trigger pulse width appearing at the output of NAND gate 120 is increased or decreased. NAND gate 120 is connected between HAND gates 122.124, each associated with transformer 50.52, identified above.

HAND game) 122, 124 are alternately enabled or energized according to the function of the elements controlled by the CMOS oscillator chip 125 (bottom left of FIG. 4) and the output therefrom. The NAND gate 122 controls a transformer 50 which acts as a holding transformer in the holding action of the grinder, whereas both transformers alternately perform the function of the degaussing action, a further transistor unit 126, 127 , respectively associated with a transformer 50.52, the former unit having a transistor 128
．． 129, and the latter unit includes transistors 130, 131.

Oscillator chip 12 having the function of controlling the demagnetization effect
5 (FIG. 4) will be explained again. The following discussion relates to the actual degaussing or reversal step, which is independent of the value of the voltage used in the trigger circuit 74 (FIG. 4). As mentioned above, the switch 62D is used to turn on the device in the hold phase, and when this switch is closed, a negative electrical signal exits the common conductor 8a and connects the unit [34] (bottom of Figure 4). This unit includes NAND gates 135, 136 leading to the base of transistor 142. This signal turns on transistor 142 and NAN[
l gate! 22, NANO gate 122 turns on transistors 128, 129,
The transformer 50 is then energized and the control is set to VARIABLE.
Alternatively, it remains energized as long as it is in FULL mode. The transformer 50 functions to keep the secondary 5051.5O32 (see FIG. 3) energized so that power is applied to the chuck (20) as described again below.

The CMOS oscillator chip 125 and associated circuitry is connected to another transistor 144 (middle in FIG. 4) and three NA
146, 148, 150 (bottom of Figure 4), the first gate associated with transistor 142, the second gate associated with transistor 144, whereas Third gate 150 is associated with RC network 152 and includes RC network 15
2 controls the CMOS oscillator chip 125.

CMOS oscillator chip 125 and associated circuitry further includes capacitor 155 and resistors 156,157.

The RC network also includes a slide switch 153 that directly controls the oscillator chip 125 and allows adjustment for fast, medium, and slow speeds of reversal of the DC applied to the chuck through it. Make it. This slide switch has a resistor 157b configured for each connection in the network according to the position of the slide switch to produce a corresponding speed inversion.

157c.

When the potentiometer 64 (below the 7th [i! In fact, this causes capacitor 103
(Figure 4, top) changes the rate at which it charges, thereby directly controlling the output, causing the output to vary from a minimum to a maximum at the corresponding selected setting of the potentiometer. This gives the holding transformer 50 a corresponding maximum magnetic charge of a smaller value, and the transformer 50 has a corresponding maximum magnetic charge of a smaller value, the purpose of which is as stated above, in order to eliminate distortion of the workpiece that can result from large holding forces. The workpiece is held on the chuck with a small force.

To place the device into a degaussing operation, it is placed in RELEASE mode. That is, R11! LEASE switch 62A (
6) and close the chip 163 (bottom of Fig. 6).
Pin Ill (left of figure) goes OLD and pin 112 goes LO, which opens digital switch 96 (top of Figure 7), disconnects potentiometer 64 (bottom of Figure 7), and gates 165 (Top of Figure 5) pin +111 is II
I, which closes digital switch 167 (top of FIG. 5), which discharges capacitor 98. This causes the voltage at pin I5 of driver 7B to gradually decrease, which in turn causes the voltage at pin I5 of capacitor 98 to gradually decrease.
C output also decreases. At this stage, manual switch 1
Resistor 160 controlled by 58 (bottom right of Figure 7)
is placed in the circuit, and the switch is selectively movable into three positions for this purpose, one position shown in solid lines and each of the other positions shown in dashed lines. These resistors, individually identified as 160a and 160d, are placed in the circuit in parallel with the associated resistor 160c (top left in FIG. 5) to increase the rate of discharge of capacitor 98.

At low speed positions of discharge, only resistor 160c is in the circuit, at medium speeds resistors 160c and 160a are in the circuit, and at high speeds two resistors 160b and 160c are in the circuit. At the same time, the oscillator chip 12
5 (bottom left of FIG. 4) is enabled, which inverts the polarity of the DC output to chuck 20 (bottom left of FIG. 3). When resistor 86 (top of FIG. 5) is switched out of the circuit, conductor 11a from chip 96'' (center of FIG. 5) becomes ), which causes gate 170 to
The output of (top of FIG. 7), ie its pin 114, becomes obsolete. This places the potentiometer 64 (bottom of Figure 7) in the circuit, at which point the VARIABLE or FUL
The L mode can be selected and implemented.

Decrease the voltage for the entire time cycle! l! It is pointed out that the feature of one-nodeability and the feature of adjustability of the whole cycle in reverse are not dependent on each other. This gives higher precision, and this is very advantageous when the hardness and structure of the workpieces differ and when other factors influence the degaussing operation.

In this degaussing operation, the closed REL[! A.S.
In response to E switch 62^, capacitor 155 (fourth
(bottom left of the figure) and resistors 156, 157 determine the overall operating frequency, whereas switch 158 (bottom right of figure 7) controls the capacitor 98 which determines the cycle time. Gives fast, medium or slow discharge.

The output from the oscillator chip 125 in the bin 116 is one input of the NAN logger 148.146 and the clock power 172 of the flip-flop unit 162.
, i.e. applied to bin 113 (bottom right of FIG. 4).

The outputs of unit 162 are connected to NAND gate 148.1.
46, thus turning either transistors 142, 144 on or off, depending on the cycle. Transistor 142 is HA
ND gate 122 is enabled, whereas transistor 144 enables NAND gate 124.

Here, in FIILL mode as above, FUL
We refer to the VARIABLE mode in which the workpiece is held on the chuck with a force less than L holding force. This VA
In RIABLE mode, potentiometer 64 (
The arm 65 of FIG.
cent at the position of a predetermined value, which is 74.

To implement this mode, the operator must
When the ABLE switch 62c (bottom right of FIG. 6) is closed, the flip-flop chip 94 (middle left of FIG. 7), according to its internal characteristics, puts its bin #10 at Hl, which causes this chip to Bin 1112 becomes Hl,
Bin 112, which is HI, turns off transistor 95 and connects the FULL mode circuit to the old point 93 of the potentiometer.
Open from. At the same time, this old signal is transferred to digital switch 1
Close terminals 8 and 9 of 73. This enables potentiometer 64 (bottom of FIG. 7), which is connected to pin I5 of driver 78 (bottom of FIG. 5).
control the voltage applied to the

To further explain the operation of transformer 50.52, for example, while transformer 50 is energized as controlled by NAND gate 122, the ON set of secondary 5051.5082 (FIG. 3) is energized. 5CR56
is turned on, completing the circuit from power transformer 32 to the chuck. In this phase or mode, the chuck is energized whenever transformer 50 is energized, and this applies to both holding and degaussing.

At alternate intervals in which transformer 52 is energized in the degaussing phase or mode, the secondary 52 of the EMAG set is energized, which turns on 5CR 58, resulting in a loss of power from power transformer 32 to the chuck. The circuit is completed.

In the case of transformers 50, 52, it will be noted that in each case the secondary side performs a full-wave rectification of the current and is opposed to give a constant holding force to the chuck, corresponding to this construction: Each set, i.e. ON set and DI! in the demagnetization phase or demagnetization mode! The MAG set operates at corresponding intervals defined by the trigger and oscillator circuits mentioned above and again below.

RESIDtlAL-11--D is RESIDIIA
This is carried out by closing the L switch y Chiro 2B (bottom of Fig. 6), and at this time, the flip 7 flip chip 174 (
The bin 112 (in the middle of FIG. 6) becomes LO. The signal from this stage is in bin #2 of gate 120 (middle of Figure 4).
Applies to.

This stops the trigger pulse from appearing at the output in the bin 113 of this gate, i.e. through the transistor unit 126, 127 to the respective transformer 50.
There is no DC output up to 52.

The effect of this phase is to increase the retention force so that the workpiece can be removed, for example for testing purposes, and the remaining workpiece
The objective is to reduce these to a level such that they are held in place without any external input to remove them from that position. After such testing, the removed workpiece is repositioned and the holding force is re-established to the desired level, eg, FULL or VARIABLE.

The device includes means for visually indicating the individual stages in the demagnetization phase. For this purpose, a dot bar driver 176 is provided (bottom of FIG. 7). This dot driver is equivalent to unit 78 (bottom of FIG. 5), with bin #5 interconnected, i.e., conductor 9
K (lower left in Figure 7) passes through Figure 6 to the boss) 115 (
In driver 78 (FIG. 5), bin I5 is also connected to post 115 (bottom center in FIG. 5). As the voltage increases in bin #5, resistor 86.88 (top right of FIG. 5) is switched into circuit and at the same time LE017B (bottom of FIG. 7) lights up from bin Ill.

The dot bar driver 176 is connected to the LE11 shown in the diagram.
Contains 178. The -th LED, when illuminated, indicates the first power level and as the voltage increases further, the other resistors 86, 88.98' (top right of Figure 5) adjust to the respective power level indicated. They are switched into the circuit one by one along with the corresponding LED. Therefore, as the DC output increases from zero, each LED lights up to indicate the power level, when all LEDs are lit, FULL mode is established, and when some, but not all, of these LEDs are lit, the VA
RIABLE mode exists and the number of LEDs lit is
Indicates the level of holding power.

Means are provided for sensing the state of the chuck in grinding and chunk control operations and thereby determining and controlling the operation of the machine (grinder) to which the device is applied. For example, if the course of the operation occurs, e.g. interruption of the electrical current to the chuck, and thus the workpiece is not correctly held on the chuck, the continuation of the grinding phase will cause the held workpiece to move out of position. This can lead to damage to the workpiece. The device includes a current sensing component for stopping the grinder or otherwise performing a control action.

This component is shown in its entirety at reference numeral 180 (bottom right of FIG. 3) and includes a current sensing resistor 182, the voltage drop across which is determined by a comparator 184.
is applied to the inverted input bin.

A reference voltage is set at comparator inverting input bin #3 which is adjusted by potentiometer 186. When the voltage on bin W2 becomes higher than the voltage available on bin I3, the comparator output bin #6 goes LO. In either FULL mode or VARIABLE mode, the comparator output (bin +16) is applied through gate 188.190 to the base of transistor 192, which turns on transistor 192, which turns on obtocambler device 194. and this device triggers the triac 196.

Then, the triac connects contacts 198b and 198c.
energizes relay 198, which includes (bottom right of Figure 3). This relay 198, through these contacts, controls the operation of the grinder as indicated above, according to the chuck status. That is, as long as the chuck is in proper working condition and holds the workpiece in place, the grinder will continue to work, but if the current stops, the grinding wheel cannot be lifted from the workpiece, etc. Appropriate measures will be taken. Conveniently, these contacts 198b and 198c are normally open and closed, respectively. However, other devices may be used if desired.

The present invention includes a novel lockout feature to prevent the invention from being inadvertently placed in an inappropriate mode, thus allowing operators to continue operating these machines and equipment. You have to go through the steps of a specific pattern. This lockout mode allows the device to
Can only be performed after being set to either ULL or VARIABLE. This lockout feature can be applied by incorporating a switch or control means into the device for this purpose, or it can be integrated into the grinder to which the device is applied. However, in any case, the lockout control is
00, 202 (bottom right of FIG. 7), respectively. An ACN source 30 (top of FIG. 3), such as that used in the present invention, of 115 volts, is applied to these posts, thereby turning on transistor 204 (right of FIG. 7), thereby causing negative is applied to the inverter gate 206, thereby causing the pin ! of this gate to 1
10 becomes old. This turns off transistor 208, thus disabling all switches 62. The output of gate 206 is also applied through pin #10 to inverter gate 170 (top of FIG. 7), which opens digital switch 97, which turns potentiometer 64 (bottom of FIG. 7) on. removed from the circuit. Digital switch 167 (top left in FIG. 5) is also opened through inverter gate 165 (top left in FIG. 5). Opening this digital switch 167 prevents capacitor 98 from discharging, thereby keeping the voltage at pin 115 of driver 78 constant.

The voltage from pin 110 of 206 (middle of FIG. 7) is also applied to the memory J inputs of chips 96', 96'' and 97#, pin 115.

As a result, no matter which of the resistors 86, 88, 98' are switched into the circuit during the period that the lockout signal is applied, they remain switched in until the lockout signal is removed. In fact, the DC output is kept at a certain preset level until the lockout signal is removed. When the lockout signal is removed, the DC output remains at the level it had when the lockout signal was applied because the voltage at pin #5 of driver 78 remains constant. The result is that the digital switch 97 (upper part of FIG. 7) and the
This occurs because 67 (top of Figure 5) is still open. Once the lockout is removed, the only mode in which the device can be reset is R1! IP! It is ASE.

[Brief explanation of the drawing]

FIG. 1 is a simplified diagram of a grinder in which a degaussing device according to the present invention is used. FIG. 2 shows the arrangement of FIGS. 3-7 combined to form a complete circuit diagram; FIG. FIG. 3 is a diagram showing a part of the electric circuit. FIG. 4 is a diagram showing another part of the electric circuit. FIG. 5 is a diagram showing still another part of the circuit. FIG. 6 is a diagram showing additional parts of the circuit. FIG. 7 is a diagram showing the last part of the circuit. 12... Grinder 14... Stand 18...
・Workpiece 20...Magnetic chuck 22・
... Grinding wheel 24 ... Engraving of vertical slot drawing (no change in content) Procedural amendment (March 1988) - Today 1, Display of case 1988 Patent Application No. 24871 2, Name of invention Degaussing device and Method 3, Relationship with the case of the person making the amendment Patent Applicant Address Name Electro-matic Products φ Company Shin-Otemachi Building Room 206 Room 5 Appropriate drawing to be amended °＼-゛:4″nee・,7 ′

Claims (1)

[Scope of Claims] 1) An apparatus for demagnetizing a chuck having an electromagnet in operative relationship, comprising: circuit means for circuitly connecting said chuck to a power source; and said circuit means for generating a voltage. transformer means in which said circuit means is operable to apply said voltage to said electromagnet; a first dot bar driver operable to be energized by said circuit means; a plurality of resistors operatively associated with the dot bar driver of the dot bar driver and adjustably controlling a voltage applied to the dot bar driver, thereby connecting a corresponding number of the resistors with the dot bar driver; and means for applying a corresponding voltage to said chuck, said apparatus comprising: means for visually displaying the value of said voltage applied to said chuck. 2) the visual display means includes a second dot bar driver operably connected in parallel with the first dot bar driver; the device includes a plurality of signal lights each corresponding to the resistor; a second dot bar driver is operable to illuminate the signal light in association with each of the resistors connected as described above; and the first dot bar driver is operable to selectively intermittent the resistors. and means for degaussing the chuck operable to apply a voltage to the chuck in a series of steps to progressively decreasing values, wherein the second dot bar has a corresponding one as described above. 2. The apparatus of claim 1, wherein said apparatus is operable to individually turn off said lights in conjunction with an intermittent display of resistance. 3) the device is capable of being set in each of a plurality of retention modes in which retention forces having different values are established and in a non-retention mode in which no retention force is present; switch means for selectively setting said modes; said circuit means includes lockout means operable to disable said switches; said circuit means includes lockout means operable to disable said switches; 2. The device of claim 1, further comprising means operable to reset the device only in a mode of less than full holding force following disabling of the means. 4) The chuck is used in a machine tool, such as a grinder, and the circuit is a control means for energizing the grinder in response to energizing the chuck. control means for disabling the grinder in response to a disturbance, the circuit being operable to selectively provide different levels of energization of the chuck, the control means comprising: said circuit means is operable to disable said grinder at any level of energization of said chuck, said circuit means selectively determining the value of the voltage being applied to said dot bar driver, thereby 2. The dot bar driver including a manual set switch means for controlling the number of output resistors placed in the circuit and thereby controlling the value of the voltage being applied to the chuck. equipment.