JP3075761B2 - Method and apparatus for controlling magnetic chuck - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling a magnetic chuck for moving a plurality of movable members into and out of a work surface for adsorbing a magnetic material by a fluid.

[0002]

2. Description of the Related Art A magnetic material such as a curved iron plate has a so-called irregular surface whose surface to be attracted is not aligned with the working surface of a magnetic chuck. When the magnetic chuck is released while being bent so as to be aligned with the work surface and is released from the magnetic chuck, it returns to the original curved state again by its own restoring force.

When a magnetic material having such properties is attracted to a magnetic chuck and machine processing such as grinding is performed to make the surface to be processed flat, the magnetic material is attracted to the chuck by the chucked surface. While the magnetic material is released from the chuck, the magnetic material is bent back to its original shape by the restoring force of the magnetic material itself, resulting in a curved surface.

In order to solve such a problem, a plurality of pins are made to protrude from a work surface by a fluid such as compressed air in accordance with the shape of a surface to be attracted of a magnetic material, that is, by following the surface to be attracted, There has been proposed a magnetic chuck that attracts a magnetic body while maintaining its original curved shape.

However, in this type of magnetic chuck, when the pins are projected from the work surface, the magnetic material is pushed up by the pins, and as a result, the magnetic material is pushed away from the work surface and the magnetic material is correctly attracted. Can not.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to enable a magnetic material having an irregular surface to be correctly attracted to a work surface by a movable member such as a pin without pushing the magnetic body away from the work surface.

[0007]

According to a method of controlling a magnetic chuck of the present invention, a work surface is placed in a weakly excited state in which an attracted surface maintains its original shape even if the attracted surface is irregular, and a predetermined movable Switching the work surface from the weakly excited state to the strongly excited state in a state where the member is protruded from the work surface by the fluid and the predetermined movable member is protruded from the work surface.

According to the magnetic chuck control device of the present invention, the first exciting current and the work surface are set such that the work surface is maintained in a weakly excited state in which the suction surface maintains its original shape even if the suction surface is irregular. An exciting current generating means for selectively generating a second exciting current for keeping a strong excitation state; a flow path controlling means for controlling a flow path of a fluid so that a predetermined movable member enters and exits the work surface; When the body is attracted to the work surface, a first instruction signal for generating the first excitation current is supplied to the excitation current generation unit, and then a predetermined movable member is caused to protrude from the work surface. Main control means for supplying a second instruction signal to the flow path control means and thereafter supplying a third instruction signal for generating the second excitation current to the excitation current generation means.

The magnetic material having an irregular surface is weakly attracted to the work surface when the work surface is in a weakly excited state. Since the attraction force at this time is weak, the magnetic body is not deformed so that the attracted surface of the magnetic body matches the work surface of the magnetic chuck.

Next, when a fluid force acts on the movable member, a predetermined movable member corresponding to the curved shape of the surface to be attracted of the magnetic body is projected from the work surface by a predetermined amount, and their leading ends contact the surface to be attracted. Touch At this time, since the magnetic body is weakly attracted to the work surface, the magnetic body is not pushed away from the work surface by the movable member.

Thereafter, when the work surface is switched to the strongly excited state, the magnetic material is strongly attracted to the work surface. At this time,
The deformation of the magnetic body so that the attracted surface of the magnetic body matches the work surface of the magnetic chuck is prevented by the protruding movable member, and the magnetic body is strongly contacted with the tip of the movable member.

As described above, according to the present invention, first, the work surface is set to the weakly excited state in which the attracted surface maintains its original shape even if the attracted surface is irregular, and then the predetermined movable member is moved. Since the work surface is made to protrude from the work surface, and then the work surface is switched to the strongly excited state, the magnetic member having the irregular surface can be correctly attracted by the movable member without being pushed away from the work surface.

[0013]

First, an embodiment of a magnetic chuck for a magnetic material having an irregular surface will be described. Referring to FIGS. 1-3,
The magnetic chuck 10 is an electromagnetic chuck that attracts a magnetic body 12 whose surface to be attracted is a so-called irregular surface by the action of an electromagnet.

The chuck 10 has a housing 1 which is open at one end.
4, an iron core 16 arranged in the housing 14, an exciting coil 18 between the iron core 16 and the housing 14 surrounding the iron core 16, and a face plate arranged at an open end of the housing 14 so as to close the open end. 20, a bottom plate 22 disposed at a non-open end of the housing 14, and a plurality of maintaining mechanisms 24 for maintaining the magnetic body 12 in its original shape.

The housing 14 is formed in the shape of a box having one open end. The housing 14 and the iron core 16 are integrally formed of a ferromagnetic material so that the surfaces on the side of the face plate 20 are at the same height level, and have a space for accommodating the maintenance mechanism 24. The housing 14 and the iron core 16 may be formed by separate members.

The face plate 20 comprises a plurality of elongated first and second pole pieces 26, 2 arranged alternately and in parallel with each other.
8 and a spacer 30 made of a non-magnetic material disposed between the adjacent first and second pole pieces 26 and 28, and the housing 1 is provided with a plurality of bolts (not shown).
4 attached.

Each first pole piece 26 is magnetically connected to the upper surfaces of a pair of opposite walls of the housing 14 at both ends thereof, but is magnetically separated from the iron core 16. In contrast, each second pole piece 28 is magnetically connected to the upper surface of the iron core 16 at the center thereof, but is magnetically separated from the housing 14. The work surface 32 for attracting the magnetic body 12 includes the first and second pole pieces 26,
28 and a spacer 30.

Each of the holding mechanisms 24 includes a cylinder 34 defining a cylinder chamber extending in parallel with the work surface 32 and a piston movably disposed in the cylinder chamber, as shown in FIG. 36, a cylindrical guide 38 extending upward from the cylinder 34, a pin 40 movably arranged in the guide in a vertical direction, and a coil spring 42 for constantly urging the pin 40 downward.

The cylinder 34 has holes 44 communicating with the respective ends of the cylinder chamber. Each hole 44 communicates with a fluid flow passage 46 formed in the bottom plate 22. Piston 36
Is moved in the longitudinal direction of the cylinder chamber by a pressure fluid such as air or oil supplied into the cylinder chamber through the hole 44.

A part of the upper surface of the piston 36 and the lower end surface of the pin 40 are inclined surfaces that come into contact with each other. Therefore, when the piston 36 is moved to the left in FIG. 4, the pin 40 is raised against the force of the spring 42 and protrudes from the work surface. On the other hand, when the piston 36 is moved rightward in FIG. 4, the pin 40 is pushed down by the force of the spring 42 and retreats from the work surface.

One hole 44 of the maintenance mechanism 24 is commonly connected to one flow path 46, and the other hole 44 is commonly connected to the other flow path 46. Therefore, the maintenance mechanism 2
The four pins 40 are moved simultaneously. Each flow path 46 is connected to the control device 50 shown in FIG. 5 by one flow path 46 or 48 shown in FIG. 2, and the exciting coil 18 is connected to the control device 50 shown in FIG. 5 by a cord 52 shown in FIG. You.

Cylinder 34, piston 36, guide 3
8, the pin 40 and the spring 42 may be made of any of a magnetic material and a non-magnetic material. However, in order to smooth the movement of the piston, it is preferable that the cylinder 34 and the piston 36 are made of a non-magnetic material.

Next, an embodiment of the control device 50 for controlling the magnetic chuck 10 will be described with reference to FIG.

The control device 50 is connected to the commercial AC power
Rectifies the alternating current supplied through the main switch 56,
It includes a rectifier circuit 58 for generating a DC exciting current having a predetermined voltage level. The rectifier circuit 58 includes a known bridge circuit using a pair of diodes and a pair of thyristors. The generation time and the value of the exciting current from the rectifier circuit 58 are controlled by the firing pulse supplied from the gate driver 60 to the gate of the thyristor.

The exciting current generated by the rectifier circuit 58 is supplied to a switching circuit 62 for switching the direction of the exciting current supplied to the exciting coil 18. The switching circuit 62 comprises a relay driven by a driver 64,
When the magnetic material is to be attracted to the work surface, the exciting current is supplied to the exciting coil 18 as a positive exciting current, and when the magnetic material is demagnetized, that is, demagnetized, the exciting current alternates between the positive exciting current and the reverse exciting current. Switch and output. Such a switching circuit 62
Are known, for example, from Japanese Patent Publication No. 62-11484, Japanese Patent Application Laid-Open No. 62-208844, and the detailed description thereof is omitted.

The control device 50 also includes a fluid control circuit 68 for controlling the flow path of the pressurized fluid supplied from the fluid source 66 to the maintenance mechanism 24. The fluid control circuit 68 includes a fluid source 66
A solenoid valve group for switching the fluid flow path between the fluid passage and the maintenance mechanism 24. This group of solenoid valves is driven by a driver 70.

The control device 50 further includes an input unit 72 for setting various data such as a current value and inputting various commands such as an excitation start command, and various data and inputs set for the input unit. A main control circuit 74 for controlling the drivers 60, 64, 70 based on various commands input through the unit.

The input unit 72 includes setting units 76, 78 and 80 for setting the values of the strong excitation current, the weak excitation current and the demagnetization current, respectively, and an excitation command switch for instructing that the work surface is in the excited state. 82, a weak excitation setting switch 8 for setting that the work surface is initially in a weak excitation state
4, a pin setting switch 86 for setting the pin 40 to protrude, and a demagnetization setting switch 88 for setting to demagnetize the magnetic material.

Next, the operation of the control device 50 will be described with reference to FIG. When the excitation command switch 82 is turned on (step 100), the main control circuit 74 checks whether the weak excitation setting switch 84 is off or on (step 102).

When the weak excitation setting switch 84 is off,
The main control circuit 74 checks whether the pin setting switch 82 is on or off (step 104).

When the weak excitation setting switch 84 is on,
The main control circuit 74 outputs a timing signal having a phase corresponding to the value set in the setter 78 to the driver 60 together with the weak excitation command (step 106), and after a predetermined time has elapsed, executes step 104.

In step 106, the driver 60
Receives the timing signal and the weak excitation command, starts supplying a firing pulse having a phase corresponding to the phase of the received timing signal to the thyristor of the rectifier circuit 58. Thus, the current for weak excitation is supplied from the rectifier circuit 58 to the switching circuit 62.
Is supplied to the exciting coil 18 through the
Is maintained in a weakly excited state. As a result, the magnetic body 12 is attracted to the working surface by a force that does not deform, that is, a force that maintains the original shape, even if the surface to be attracted is irregular. .

In step 104, when the pin setting switch 86 is turned on, the main control circuit 64 first outputs a pin projecting command for projecting a pin to the driver 70 (step 108). 76
Is output to the driver 60 together with the strong excitation command (step 1).
10).

At step 108, the fluid control circuit 68
A predetermined solenoid valve is driven, whereby the fluid in the fluid source 66 is supplied to each maintenance mechanism 24. As a result, the pins 40 protrude according to the shape of the attracted surface of the magnetic body 12. At this time, if step 106 is executed, the work surface 32 is in a weakly excited state, and the magnetic body 12 is weakly attracted.
There is no risk of being pushed away from.

If the pin setting switch 86 is turned off in step 104, the main control circuit 64 proceeds to step 1
Execute Step 10.

At step 110, the driver 60
Receives the timing signal and the strong excitation command, switches the firing pulse supplied to the thyristor to the rectifier circuit 58 to a firing pulse having a phase corresponding to the phase of the received timing signal. As a result, the current for strong excitation is supplied from the rectifier circuit 58 to the exciting coil 18 via the switching circuit 62, so that the work surface 32 is switched to the strong excitation state, and the magnetic body 12 is strongly attracted to the work surface 32. You.

When the work surface 32 is switched to the strongly excited state, if the step 108 is executed, the magnetic material 12
A predetermined pin 40 according to the shape of the surface to be sucked is
, The magnetic body 12 is attracted without changing its shape.

Next, after the excitation command switch 82 is turned off (step 112), the main control circuit 74 determines whether the demagnetization setting switch 88 is off or on (step 114).

In step 114, if the demagnetization setting switch 88 is off, the main control circuit 74 outputs an end command to the drivers 64 and 70 (step 11).
6) End the operation. As a result, the driver 60 terminates the supply of the ignition pulse to the rectifier circuit 58. As a result, the supply of the excitation current to the excitation coil 18 is stopped, and the work surface 32 is set in the excited state.

In step 116, the driver 70
If step 108 has not been executed, the operation ends. However, during execution of step 108, driver 70 ends the operation after driving the solenoid valve in fluid control circuit 68 to retract all pins 40 from work surface 32. Thereby, the pin 40
Is retracted from the work surface by the force of the spring 42.

If the pin 40 does not retreat from the work surface even after the solenoid valve in the fluid control circuit 68 is driven by the load of the magnetic body 12 being applied to the pin 40, the following operation may be performed. . Increase fluid pressure. Or
After the magnetic body 12 is removed from the work surface, the main control circuit 7
Then, an end command is output from the driver 4 to the driver 70, and the solenoid valve in the fluid control circuit 68 is driven so that all the pins 40 are retracted from the work surface 32. Further, the magnetic material 12
Until is removed from the work surface 32, the solenoid valves in the fluid control circuit 68 continue to be driven so that all the pins 40 are retracted from the work surface 32, and the operation is terminated after the magnetic material is removed.

When the demagnetization setting switch 88 is turned on in step 114, the main control circuit 74
Is output to the driver 60 together with the degaussing command, and a degaussing command is output to the driver 64 (step 1).
18).

Thus, the driver 60 switches the firing pulse supplied to the rectifier circuit 58 to a firing pulse having a phase corresponding to the phase of the received timing signal.
As a result, the demagnetizing exciting current is supplied from the rectifier circuit 58 to the switching circuit 62.

The driver 64 energizes the relay of the switching circuit 62 at predetermined time intervals. As a result, the switching circuit 62 is switched every predetermined time, so that the exciting coil 1
The direction of the exciting current supplied to 8 is alternately reversed, and the magnetic body 12 is demagnetized, that is, demagnetized. This degaussing may be performed by gradually attenuating the degaussing current or by gradually shortening the switching time in the switching circuit 62.

When the demagnetization is completed (step 120), the main control circuit 74 proceeds to step 116.

The control device 90 shown in FIG. 7 sets the value of the exciting current in a circuit other than the main control circuit 74. Therefore, the control device 90 includes a triac 92 connected between the AC power supply 54 and the rectifier circuit 58, a gate driver 94 for triggering the triac 92, setting devices 76, 78,
A selection circuit 96 comprising three relays each individually associated with a setting device to select one of the 80;
And a driver 98 controlled by the main control circuit 74 to drive the driver 98. The selection circuit 96 is connected to the setting device corresponding to the normally open contact of each relay and the gate driver 94.

In the control device 90, when the work surface is set in the strongly excited state, the driver 98 drives the relay corresponding to the setter 76 by the control signal from the main control circuit 74, so that the setter 76 is set. A trigger pulse having a phase corresponding to the value is output from the gate driver 94 to the triac 92. As a result, the rectifying circuit 58 outputs a strong excitation current corresponding to the value set in the setting device 76.

On the other hand, when the work surface is to be set in the weakly excited state, the driver 98 drives the relay corresponding to the setter 78 by the control signal from the main control circuit 74, thereby setting the setter 78. A trigger pulse having a phase corresponding to the value is output from the gate driver 94 to the triac 92. As a result, the weak excitation current corresponding to the value set in the setting device 78 is output from the rectifier circuit 58.

When the magnetic material is demagnetized, the driver 98 controls the setting device 8 by the control signal from the main control circuit 74.
By driving the relay corresponding to 0, the setting device 8
A trigger pulse having a phase corresponding to the value set to 0 is output from the gate driver 94 to the triac 92. Thus, the rectifying circuit 58 outputs a demagnetizing current corresponding to the value set in the setting device 80.

In the rectifier circuit 58 of the control device 90, a diode is used instead of the thyristor of the rectifier circuit 58 in the control device 50. However, instead of using the triac 92, a pair of thyristors may be used for the rectifier circuit, such as the rectifier circuit in the control device 50, and the firing pulse may be output from the gate driver 96 to the thyristor.

The present invention is not limited to a magnetic chuck using only electromagnets as in the above embodiment, but also a magnetic chuck using at least one polarity reversible permanent magnet and an electromagnet.
The present invention can also be applied to a magnetic chuck using only a permanent magnet.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a magnetic chuck.

FIG. 2 is a plan view of the magnetic chuck of FIG. 1;

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is a sectional view showing an embodiment of a maintenance mechanism for maintaining a magnetic body.

FIG. 5 is a block diagram of an electric circuit showing one embodiment of the control device of the present invention.

FIG. 6 is a diagram for explaining the operation of the control device in FIG. 5;

FIG. 7 is a block diagram of an electric circuit showing another embodiment of the control device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Magnetic chuck 12 Magnetic body 14 Housing 16 Iron core 18 Exciting coil 20 Face plate 24 Maintenance mechanism 34 Cylinder 36 Piston 38 Guide 40 Pin (auxiliary member) 50, 90 Control device

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-34408 (JP, A) JP-A-54-152158 (JP, A) JP-A-64-11744 (JP, A) JP-A-1- 109042 (JP, A) Japanese Utility Model Unexamined Publication No. 2-126734 (JP, U) Japanese Utility Model Application Unexamined Publication No. 3-22840 (JP, U) Japanese Utility Model Application Showa 59-32330 (JP, U) ⁷ , DB name) B23Q 3/154

Claims (2)

(57) [Claims] 1. A method for controlling a magnetic chuck comprising a plurality of movable members that enter and exit from a work surface according to the shape of a surface to be attracted of a magnetic body by a fluid, wherein the work surface has an irregular surface. Even if there is, the surface to be attracted is placed in a weakly excited state in which the original shape is maintained, the predetermined movable member is projected from the work surface by the fluid, and the predetermined movable member is projected from the work surface. A method for controlling a magnetic chuck, comprising switching the work surface from the weakly excited state to the strongly excited state. 2. A control device for a magnetic chuck, comprising: an excitation coil for selectively setting a work surface for adsorbing a magnetic material to an excited state and a non-excited state; and a plurality of movable members that enter and exit the work surface with a fluid. A first excitation current for setting the work surface to a weakly excited state in which the attracted surface maintains an original shape even when the attracted surface is irregular, and a second excitation current for setting the work surface to a strongly excited state. An exciting current generating means for selectively generating an electric current; a flow path controlling means for controlling a flow path of the fluid so that the movable member moves in and out of the work surface; and when the magnetic body is attracted to the work surface. A first instruction signal for generating the first excitation current is supplied to the excitation current generation means, and then a second instruction signal is supplied to the flow path control so as to cause a predetermined movable member to protrude from the work surface. Means, and then said second A main control means for supplying a third instruction signal for generating an exciting current to the exciting current generating means.