JP2022144885A - Magnetic clamp device - Google Patents

Abstract

To provide a magnetic clamp device capable of detecting a position where a magnetic flux change has occurred on a magnetic plate.SOLUTION: A plurality of magnetic units (11) are provided in a magnetic plate (8) of a magnetic clamp. Each magnetic unit (11) has an Alnico magnet (14), and a search coil (20) through which an induced voltage is generated when a magnetic flux passing through the Alnico magnet (14) changes. The magnetic plate (8) is divided into a first area (22a) and a second area (22b). The search coils (20) of the magnetic units (11) arranged in the first area (22a) are serially connected. The search coils (20) of the magnetic units (11) arranged in the second area (22b) are serially connected.SELECTED DRAWING: Figure 2

Description

The present invention relates to a magnetic clamping device for magnetically attracting a mold, work, or tool to a substrate, and more particularly to measuring the induced voltage generated in the probe coil of the magnetic clamping device, and measuring the magnetic flux from the induced voltage. The present invention relates to a magnetic clamp device that calculates the amount of change.

A conventional magnetic clamping device of this type is described in Patent Document 1 (Japanese Patent Laid-Open No. 2011-206860). The prior art is configured as follows.
A magnetic plate has an attraction surface that magnetically attracts the mold. A plurality of mounting holes are opened in the attracting surface. A magnetic unit is provided for each mounting hole. The magnetic unit includes a reversing coil, an alnico magnet, and a searcher coil. The magnetic poles of the alnico magnet are reversed by a current flowing in one direction through the magnetic pole reversing coil. Also, the alnico magnet is returned to the state before the magnetic poles are reversed by the current flowing in the other direction opposite to the one direction. A search coil is wound around the outer wall of the alnico magnet. An induced voltage is generated in the search coil when the magnetic flux passing through the alnico magnet changes. The amount of change in magnetic flux is calculated from the induced voltage. All magnetic pole reversing coils in the magnetic unit are connected in series. All search coils in the magnetic unit are also connected in series.

JP 2011-206860 A

The above prior art has the following problems.
Since all the above probe coils were connected in series, the probe coils could not detect where on the magnetic plate the magnetic flux was changing.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic clamping device capable of detecting the position of magnetic flux change on a magnetic plate.

In order to achieve the above object, the present invention, for example, as shown in FIGS. 1 to 4, has constructed a magnetic clamping device as follows.
A magnetic plate 8 has an attraction surface 9 for magnetically attracting an object 7 to be magnetically attracted. A plurality of mounting holes 10 are formed in the attraction surface 9 . A magnetic unit 11 is provided for each mounting hole 10 . The magnetic unit 11 comprises a magnetic pole reversing coil 12 , a reversible magnet 14 and a search coil 20 . The magnetic poles of the reversible magnet 14 are reversed by a current flowing in one direction through the magnetic pole reversing coil 12, and are returned to the state before the magnetic poles were reversed by a current flowing in the other direction opposite to the one direction. be The change in magnetic flux passing through the reversible magnet 14 produces an induced voltage in the search coil 20 . The magnetic plate 8 is divided into a plurality of areas, and a plurality of magnetic units 11 are arranged in a first area 22a as one of the plurality of areas. The search coils 20 of the plurality of magnetic units 11 arranged in the first area 22a are connected in series, and the plurality of search coils 20 in the first area 22a constitute a first detection circuit 23a. be. The search coils 20 of the plurality of magnetic units 11 arranged in the second area 22b, which is an area different from the first area 22a, are connected in series to form a plurality of search coils in the second area 22b. The coil 20 constitutes a second detection circuit 23b.

ADVANTAGE OF THE INVENTION This invention has an effect as follows.
Since the magnetic plate is divided into a plurality of areas and the search coil is connected in series for each area, the induced voltage generated in the search coil can be detected for each area. This makes it possible to detect the state of the mold, for example, the presence or absence of the mold, the separation of the magnetically attracted mold when an external force is applied, and the deviation of the magnetic attraction position for each area.

The magnetic pole reversing coils 12 of the plurality of magnetic units 11 arranged in the first area 22a are connected in series, and the magnetic pole reversing coils 12 of the first area 22a are used for the first magnetic pole reversing. A circuit 24a is constructed. A second magnetic pole reversing circuit 24b is configured by the magnetic pole reversing coils 12 of the plurality of magnetic units 11 arranged in the second area 22b.
In this case, the magnetic pole reversing coil for the first area and the magnetic pole reversing coil for the second area can be operated separately or simultaneously according to the induced voltage generated in the search coil for each area.

FIG. 1 shows a first embodiment of the present invention and is a schematic diagram showing a molding machine. FIG. 2 is a front view showing the magnetic clamp device attached to the molding machine. FIG. 3 is a view taken along line AA in FIG. 2, showing a demagnetization state of the magnetic clamping device. FIG. 4 is a cross-sectional view showing the magnetization state of the magnetic clamping device, similar to FIG. FIG. 5 shows a second embodiment of the invention and is a front view similar to FIG.

A first embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG.
A molding machine 1 shown in FIG. 1 includes a stationary platen 2 and a support wall 3 . Four guide rods 4 are provided in parallel across the fixed platen 2 and the support wall 3 , and a movable platen 5 is provided on the guide rods 4 so as to be movable along the guide rods 4 . Magnetic clamp devices 6 are attached to the side walls of the stationary platen 2 and the side walls of the movable platen 5, respectively. The mold (object to be magnetically attracted) 7 is magnetically attracted by the magnetic force of the magnetic clamp device 6 . The magnetic clamp device 6 is constructed as follows, as shown in FIGS.

The magnetic clamping device 6 has a magnetic plate 8, which is made of a ferromagnetic member, for example, an iron member. An attraction surface 9 is provided on the magnetic plate 8 , and the mold 7 is magnetically attracted to the attraction surface 9 . A plurality of circular mounting holes 10 are formed in the attracting surface 9 of the magnetic plate 8 . One magnetic unit 11 is provided in one mounting hole 10 . The magnetic unit 11 is constructed as follows, as shown in FIGS.

A ring-shaped bobbin 13 around which a magnetic pole reversing coil 12 is wound a plurality of times is inserted into the mounting hole 10 . A reversible magnet 14 is inserted into the inner peripheral hole of the bobbin 13 and is in contact with the bottom wall 10 a of the mounting hole 10 . The reversible magnet 14 is constituted by an alnico magnet, for example. A magnetic pole member 15 composed of a ferromagnetic member similar to the magnetic plate 8 is inserted on the right side (attraction surface 9 ) of the reversible magnet 14 so as to contact the reversible magnet 14 . A ring-shaped non-magnetic member 16 is attached to the end of the outer peripheral wall of the magnetic pole member 15 on the attracting surface side. The non-magnetic member 16 is made of brass or stainless steel, for example. An O-ring 17 as a sealing member is mounted in a housing groove formed in the outer peripheral wall of the non-magnetic member 16 in the circumferential direction. A permanent magnet 19 such as a neodymium magnet is mounted in an annular space 18 defined by the non-magnetic member 16, the outer wall of the magnetic pole member 15, the bobbin 13, the inner wall of the mounting hole 10, and the like.

In the present embodiment, as shown in FIGS. 3 and 4, in one magnetic unit (hereinafter referred to as first magnetic unit 11a) of the plurality of magnetic units 11, a reversible magnet (hereinafter referred to as a first alnico 14a) is magnetized so that one end on the right side (the side close to the attracting surface 9) is the S pole. Also, the other end, which is the end opposite to the one end, is magnetized so as to be the N pole.

Another magnetic unit (hereinafter referred to as the second magnetic unit 11b) adjacent to the above-mentioned first magnetic unit 11a is constructed in the same manner as the first magnetic unit 11a, but with a reversible magnet (hereinafter referred to as the second magnetic unit). The second alnico magnet 14b differs from the first magnetic unit 14a in that the second alnico magnet 14b is magnetized so that one end on the right side (the side near the attracting surface 9) of the alnico magnet 14b becomes the N pole. The other end of the second alnico magnet 14b is magnetized to have the S pole. The coil (second coil) 12b of the second magnetic unit 11b is wound around the second bobbin 13b in the opposite direction to the coil (first coil) 12a of the first magnetic unit 11a. The second coil 12b and the first coil 12a are connected in series. The magnetic poles of the first alnico magnet 14a and the second alnico magnet 14b are switched at once by passing a predetermined amount of current through the coils 12a and 12b in one direction for a predetermined period of time.

The permanent magnet (hereinafter referred to as the first neodymium magnet 19a) of the first magnetic unit 11a is magnetized so that its inner peripheral side is N pole and its outer peripheral side is S pole. The permanent magnet (second neodymium magnet 19b) of the second magnetic unit 11b is magnetized so that its inner peripheral side is the S pole and the outer peripheral side is the N pole. Therefore, in the demagnetized state of the magnetic clamping device in which one end of the first alnico magnet 14a is the S pole and one end of the second alnico magnet 14b is the N pole, as indicated by the chain double-dashed line in FIG. , the magnetic flux moves from the first alnico magnet 14a to the magnetic pole member (first magnetic pole member 15a) of the first magnetic unit 11a, the first neodymium magnet 19a, the magnetic plate 8, the second neodymium magnet 19b, the second magnetic unit 11b through the magnetic pole member (second magnetic pole member 15b), the second alnico magnet 14b, and the magnetic plate 8 in order, and return to the first alnico magnet 14a. At this time, since a magnetic field is generated only inside the magnetic plate 8, even if the mold 7 is brought close to the magnetic plate 8, it will not be magnetically attracted.

In the magnetized state of the magnetic clamping device in which one end of the first alnico magnet 14a is switched from the S pole to the N pole and one end of the second alnico magnet 14b is switched from the N pole to the S pole, in FIG. , part of the magnetic flux starts from the first alnico magnet 14a and passes through the first magnetic pole member 15a, the mold 7, the second magnetic pole member 15b, the second alnico magnet 14b, and the magnetic plate 8. It returns in order to the first alnico magnet 14a. At this time, since a magnetic field is generated across the magnetic plate 8 and the die 7 in contact with the magnetic plate 8 , the die 7 is magnetically attracted to the magnetic plate 8 .

In the magnetic clamping device 6 of this embodiment, the search coil 20 is arranged in the annular space 18 formed between the neodymium magnet 19 and the non-magnetic member 16 so as to be wound along the outer peripheral surface of the non-magnetic member 16 . is set. The search coil 20 detects magnetic flux passing through the magnetic pole member 15 and alnico magnet 14 . The search coil (first search coil) 20a of the first magnetic unit 11a is connected in series to the search coil (second search coil) 20b of the second magnetic unit. The second search coil 20b is arranged so as to be wound along the outer peripheral surface of the non-magnetic member 16 of the first magnetic unit 11b in the opposite direction to the first search coil 20a. A communication hole 21 for communicating the mounting hole 10 of the first magnetic unit 11a and the mounting hole 10 of the second magnetic unit 11b is opened in the back surface of the magnetic plate 8, and one end of the first search coil 20a and the first search coil 20b are connected. is inserted into the communication hole 21 . The search coils 20 a and 20 b are connected within the communication hole 21 . Thus, the search coils 20a, 20b of adjacent magnetic units 11a, 11b are connected in series. The voltmeter of the control device measures the induced voltage generated in the search coils 20a and 20b at predetermined intervals (about 1 msec). The measurement results are sent to and recorded in the memory section of the control device. From the induced voltage e and the number of turns N of the coil recorded in the memory section, the amount of change dφ of the magnetic flux is calculated by the calculation section of the control device using the following equation.
e=-Ndφ/dt
In the above equation, the magnetic flux change amount φ is calculated by integrating the output voltage e over time and dividing it by the number of turns N of the coil.

In the magnetic clamping device 6 of the above embodiment, the magnetic flux changes when the magnetic clamping device 6 is switched from the demagnetized state to the magnetized state, and the amount of change in the magnetic flux is called initial magnetic flux. Further, when the mold 7 magnetically attracted to the magnetic plate 8 begins to peel off due to an external force or the weight of the mold itself, or when the magnetic attraction position shifts, the magnetic flux changes from the initial magnetic flux so as to decrease. The magnetic flux is called flux vanishing.

As described above, when the mold 7 is about to peel off, the magnetic flux decreases from the initial magnetic flux by the amount of the magnetic flux disappearance. When the value obtained by subtracting the vanishing magnetic flux value from the initial magnetic flux falls below a preset threshold value, the determination unit of the control device determines that there is a possibility that the mold 7 will fall from the magnetic plate 8. At this time, the determination unit transmits a signal corresponding to the determination result to the warning device. The warning device displays a warning or the like that the mold 7 may fall from the magnetic plate 8 .

As described above, when the warning is displayed, the operator or the like finds that the mold 7 has hardly moved from the position on the magnetic plate 8 where it was initially magnetically fixed and that there is no problem in driving the molding machine 1. If it is confirmed, the following re-magnetization operation is performed. In the remagnetization operation, first, the movable platen 5 is moved toward the fixed platen 2 and the mold 7 is sandwiched between the movable platen 5 and the fixed platen 2 . Next, the magnetic clamp device 6 is switched from the magnetized state to the demagnetized state, and then switched from the demagnetized state to the magnetized state again. Thereby, the magnetic flux of the magnetic clamping device 6 can be returned to the initial state before disappearance.

In this embodiment, as shown in FIG. 2, 24 magnetic units 11 are arranged on the magnetic plate 8 . The magnetic plate 8 is divided vertically and horizontally into four areas. When viewing the magnetic plate 8 from the front, the upper right area is called a first area 22a, the lower right area is called a second area 22b, the lower left area is called a third area 22c, and the upper left area is called a fourth area 22d. shall be called. Six magnetic units 11 are arranged in the first area 22a. The search coils 20 of the six magnetic units 11 are connected in series as indicated by dotted lines in FIG. It is connected to a controller (not shown). The electric wiring for the detection circuit 23 (including not only the first detection circuit 23a but also the second detection circuit 23b to the fourth detection circuit 23d, which will be described later) is formed in grooves formed in the rear wall of the magnetic plate 8 or the like. Disposed within the bore. Similarly, electric wiring as the inverting circuit 24 (first inverting circuit 24a to fourth inverting circuit 24d), which will be described later, is also arranged in grooves or holes formed in the rear wall of the magnetic plate 8. be done. For this reason, the detection circuit 23 and the inversion circuit 24 are shown together by dotted lines in FIG. there is

Six magnetic units 11 are also arranged in each of the second area 22b to the fourth area 22d other than the first area 22a, and the six search coils 20 of the six magnetic units 11 are connected in series. (second detection circuit 23b to fourth detection circuit 23d). By measuring the induced voltage generated in the six search coils 20 for each area, the controller can calculate the amount of magnetic flux change for each area when the magnetic flux disappears. As a result, the control device can detect for each area that the mold 7 magnetically attracted to the magnetic plate 8 has moved relative to the magnetic plate 8 or has come off. Also, the control device determines that the mold 7 may fall from the magnetic plate 8 when the total amount of magnetic flux change in each area exceeds a predetermined value.

In the six magnetic units 11 arranged in each area 22, the coils 12 for reversing the magnetic poles of the alnico magnets 14 are connected in series to form a magnetic pole reversing circuit 25 (first magnetic pole reversing circuit 25a). The end of the magnetic pole reversing circuit 25a is connected to a power supply (not shown). The magnetic units 11 in other areas are also connected in series for each area (second magnetic pole reversing circuit 25b to fourth magnetic pole reversing circuit 25d). Therefore, when the control device determines that there is a risk that the mold 7 may fall off the magnetic plate 8, the magnetic clamping device 6 is turned on to return the magnetic force that magnetically attracts the mold to the initial state. is once demagnetized, and then switched to the magnetized state. The procedure is as follows. First, the magnetic flux at which the mold can be magnetically attracted without being dropped by the magnetic units in three of the four areas is measured or calculated in advance for each mold, and the measured value or calculated value (hereinafter referred to as measured value, etc.) is stored in the memory section of the control device as a reference value. When the sum of the magnetic fluxes in three of the four areas reaches the reference value, the operation of the molding machine 1 is stopped (if the operation of the molding machine 1 is not affected, the molding machine 1 is operated. The magnetic unit 11 in one of the four areas 22 is switched from the magnetized state to the demagnetized state and then switched back to the magnetized state (hereinafter referred to as re-magnetization operation). This re-magnetization operation is sequentially performed in the magnetic units of the other three areas. Therefore, unlike the aforementioned conventional magnetic clamping device in which the mold must be sandwiched between the stationary platen and the movable platen, the magnetic clamping device 6 of this embodiment does not need to sandwich the mold 7 . Therefore, the magnetic clamping device of this embodiment can simplify the re-magnetization operation.

FIG. 5 shows a second embodiment of the invention. In this second embodiment, in principle, the same reference numerals are attached to the same members (or similar members) as the constituent members of the first embodiment. The difference of the second embodiment from the first embodiment is as follows.

The magnetic plate 8 shown in FIG. 5 is divided into five areas. The central area of the five areas is called a first area 22a, and the two areas arranged separately on the right side and the left side of the first area 22a are combined to form a second area. The area 22b is called the area 22b, and the two areas on the left and right sides of the second area 22b are collectively called the third area 22c. Sixteen magnetic units 11 are provided in the first area 22a, and the magnetic pole reversing coils 12 of the sixteen magnetic units 11 are connected in series, and the search coils 20 are also connected in series. In the eight magnetic units 11 in the second area 22b and the eight magnetic units in the third area 11, the coils 12 for reversing the magnetic poles and the search coils 20 are arranged in series for each area as in the first area 22a. connected to

In the magnetic clamping device 6 , molds 7 of different sizes may be magnetically attracted to the magnetic plate 8 . For example, a large mold 7A whose size is large enough to cover all areas, a medium mold 7B whose size is large enough to cover the first area 22a and the second area 22b, and only the first area 22a When the small mold 7C is large enough to cover, the magnetic clamp device 6 magnetically attracts each mold 7 to the magnetic plate 8 in the following procedure. First, when the large mold 7A sandwiched between the fixed platen 2 and the movable platen 3 is magnetically attracted, the magnetic units 11 in the first area 22a and the second area 22b are operated to change from the demagnetized state to the magnetized state. switch. At this time, the magnetic flux is calculated from the induced voltage generated in the search coil 20 in the second area 22b. When the calculated magnetic flux value is equal to or greater than a predetermined value, the magnetic unit 11 in the third area 22c is activated. As a result, the large mold 7A is attracted and fixed by the magnetic units 11 in the three areas.

The procedure for magnetically attracting the medium mold 7B to the magnetic plate 8 by the magnetic clamping device 6 is the same as that for the large mold 7A. At this time, since almost no induced voltage is generated in the search coil 20 in the third area 22c, the control device detects that the size of the mold 7 is medium.

When the magnetic clamping device 6 magnetically attracts the small mold 7C to the magnetic plate 8, first, the magnetic units 11 in the first area 22a and the second area 22b are operated to switch from the demagnetized state to the magnetized state. At this time, almost no induced voltage is generated in the probe coil 20 in the second area 22b, so the control device detects that the size of the mold 7 is small. Further, since the small mold 7 can be sufficiently magnetically attracted to the magnetic plate 8 by the magnetic units 11 in the first area 22a and the second area 22b, current is not supplied to the coils 12 of the magnetic units 11 in the third area 22c. . Therefore, since the magnetic unit 11 in the third area 22c is not operated, power consumption can be kept low.

Each of the above embodiments can be modified as follows.
In the above embodiment, the search coil 20 is provided for all the magnetic units 11, but the search coil 20 is selectively provided for one of the magnetic units 11 arranged in the area 22. can be Also, instead of being inserted into the annular space 18 by one turn, the probe coil 20 may have more than one turn or less than one turn.
Although the magnetic plate 8 is divided into three or four areas in the above embodiment, the number of areas is not limited to two and may be five or more.
In the above embodiment, the search coil 20 and the magnetic pole reversing coil 12 are separate coils, but the magnetic pole reversing coil 12 may be switched and used as the search coil 20 . When the magnetic pole reversing coil 12 is used as the search coil 20, a switching circuit is provided. Since the magnetic pole reversing coil 12 has a plurality of turns on the bobbin 13, there is an advantage that the sensitivity is improved as compared with the case where the number of turns is small.
The search coil 20 may be arranged so as to be wound around the outer circumference of the magnetic pole member 15 or the outer circumference of the alnico magnet instead of being wound around the outer circumference of the non-magnetic member 16 .
The warning device is not limited to the exemplified LED display device, and may be a speaker, a warning lamp, etc., as long as the type of warning can be recognized.
In the above embodiment, one end of the first alnico magnet 14a of the first magnetic unit 11a is magnetized to the S pole and the other end is magnetized to the N pole, and the second alnico magnet 14b of the second magnetic unit 11b One end is magnetized to N pole and the other end is magnetized to S pole. Alternatively, one end of the alnico magnets 14 of all the magnetic units 11 may have the same magnetic pole. As a result, when both the end of the alnico magnet 14 facing the magnetic pole member and the end of the neodymium magnet 19 have the same magnetic pole, the magnetic flux will flow from the alnico magnet 14 as a starting point to the magnetic pole member 15, the mold 7, and the magnetic plate. 8. Return to alnico magnet 14; At this time, the mold 7 is magnetically attracted to the attraction surface 9 of the magnetic clamp device 6 . When both the end of the alnico magnet 14 facing the magnetic pole member 15 and the end of the neodymium magnet 19 have different magnetic polarities, the magnetic flux is generated from the alnico magnet 14 as a starting point through the magnetic pole member 15, the neodymium magnet 19, the magnetic plate 8, Back to alnico magnet 14 . At this time, even if the mold 7 is brought close to the magnetic clamping device 6 , it is not magnetically attracted to the magnetic clamping device 6 .
Instead of arranging a plurality of magnetic units 11 in each area 22, one magnetic unit 11 may be arranged in one area. In this case, the detection circuit consists of one search coil and wiring connecting the search coil and the controller.

7: mold (object to be magnetically attracted), 9: attraction surface, 8: magnetic plate, 10: mounting hole, 11: magnetic unit, 12: magnetic pole reversal coil, 14: alnico magnet (reversible magnet), 20: Searching coil 22: area 22a: first area 22b: second area 23a: first detection circuit 23b: second detection circuit 24a: first magnetic pole reversal circuit 24b: second magnetic pole reversal circuit.

Claims (2)

a magnetic plate (8) having an attraction surface (9) for magnetically attracting a magnetic attraction target (7);
a plurality of mounting holes (10) opened in the adsorption surface (9);
A magnetic unit (11) provided for each mounting hole (10),
The magnetic unit (11) comprises:
a magnetic pole reversal coil (12);
A reversible magnet whose magnetic poles are reversed by a current flowing in one direction in the magnetic pole reversing coil (12) and returned to the state before the magnetic poles were reversed by a current flowing in the other direction opposite to the one direction. (14) and
a search coil (20) in which an induced voltage is generated by changing the magnetic flux passing through the reversible magnet (14),
The magnetic plate (8) is divided into a plurality of areas (22), and the plurality of magnetic units (11) are arranged in a first area (22a) which is one of the plurality of areas (22). is set up,
The search coils (20) of the plurality of magnetic units (11) arranged in the first area (22a) are connected in series to form a plurality of search coils (20) in the first area (22a). A first detection circuit (23a) is configured by
The search coils (20) of the plurality of magnetic units (11) arranged in the second area (22b), which is an area different from the first area (22a), are connected in series to form the first area (22a). A magnetic clamping device, characterized in that a second detection circuit (23b) is constituted by a plurality of said search coils (20) in two areas (22b). The magnetic clamping device of claim 1, wherein
The magnetic pole reversing coils (12) of the plurality of magnetic units (11) arranged in the first area (22a) are connected in series to form the magnetic pole reversing coils (12) of the first area (22a). The coil (12) constitutes a first magnetic pole reversing circuit (24a),
A magnetic field characterized in that a second magnetic pole reversing circuit (24b) is configured by the magnetic pole reversing coils (12) of the plurality of magnetic units (11) arranged in the second area (22b). clamping device.

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