Fall protection device for object to be adsorbed

Abstract

To provide a fall protection device for an object to be adsorbed in which connection of a link chain for mold fall protection with a magnetic plate is easily checked.SOLUTION: There is provided a fall protection device for an object to be adsorbed which is configured in that: a link chain (19) is attached to an object (4) to be absorbed; a connecting mechanism (C) attached to a top of a magnetic clamp (3) is detachably connected with the link chain (19) onto the magnetic clamp (3); an attachment link (20a) of the link chain (19) can be inserted into a mounting groove (22) provided in an upper part of a block (21) of the connecting mechanism (C); and a detector (28) fixed to a hole opened in a wall of the mounting groove (22) detects that the mounting link (20a) is mounted in the mounting groove (22).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for preventing an object to be attracted, such as a mold or a workpiece, magnetically attracted to a magnetic clamp from falling off the magnetic clamp. [Background technology]

[0002] A conventional device for preventing the fall of this type of object to be sucked (mold) is disclosed in Patent Document 1 (Japanese Utility Model Registration No. 3136001). This conventional technology is configured as follows. The mold drop prevention device is installed above the fixed platen and movable platen of the molding machine. Magnetic clamps are attached to the side walls of the fixed platen and movable platen of the molding machine. The mold is removably fixed to the magnetic plate of the magnetic clamp by magnetic force. Multiple coils and permanent magnets are installed in mounting holes formed in the magnetic plate.

[0003] The base end of the link chain is attached via a hook to an eyebolt attached to the top of the mold. The tip end of the link chain is detachably attached to the mold fall prevention device. The mold fall prevention device includes a rectangular parallelepiped block. The block is fixed with bolts to the top of the fixed platen and the top of the movable platen, respectively. A groove for inserting the link chain is formed in the center of the block. A horizontal link, which is a link of the link chain and has its inner hole oriented in the vertical direction, is inserted into a first groove portion of the groove. A second groove portion is formed on the mold side of the bottom wall of the first groove portion. A vertical link, which is a link adjacent to the horizontal link on the mold side and has its inner hole oriented horizontally, is inserted into the second groove portion. A cover member that prevents the horizontal link from slipping out of the first groove portion is detachably bolted to the block. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Utility Model Registration No. 3136001 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-described conventional technology, workers are sometimes required to make a final visual check to ensure that the link chain for preventing mold falls is connected to the mold fall prevention device and the mold. Such visual checks often require workers to work at heights to see the top of large molds, or in environments with poor footing or narrow spaces. This visual check is therefore time-consuming. Furthermore, even if a worker forgets to connect the link chain to the mold fall prevention device, peripheral equipment such as an injection molding machine can still be operated. In such cases, if the force of the magnetic clamp magnetically adsorbing the mold to the fixed platen or other device weakens for some reason, the mold may fall from the fixed platen and movable platen to the floor and be damaged. An object of the present invention is to make it possible to easily confirm whether a link chain for preventing a die from falling is connected to a fixed platen, a movable platen, or a magnet plate. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a magnet clamp system configured as follows, for example, as shown in FIGS. 1 to 5. An object to be attracted 4 is magnetically attracted to the attraction surface 5a of a magnetic clamp 3 by a magnetic clamp 3 provided on the side wall of the base 1, 2. A base end 19a of a link chain 19 is attached to the object to be attracted 4. The link chain 19 is composed of a plurality of links 20 connected together. A connecting mechanism C is attached to the top of the magnetic clamp 3 or the base 1, 2. The connecting mechanism C detachably connects a tip end 19b of the link chain 19 to the magnetic clamp 3 or the base 1, 2. An attachment groove 22 is provided on the top of a block 21 of the connecting mechanism C. An attachment link 20a, which is one of the plurality of links 20, can be inserted into the attachment groove 22. A detector 28 is fixed to a hole opened in a wall surface that constitutes the attachment groove 22. The detector 28 detects that the attachment link 20a has been attached to the attachment groove 22.

[0007] The present invention has the following advantages. Simply inserting a link chain into the mounting groove of the block of the connecting mechanism reliably prevents the object from falling out of the magnetic clamp. In addition, the fact that the link chain has been mounted in the mounting groove can be easily detected by a detector. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a magnet clamp system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a partial enlarged view showing part A in FIG. 1, and shows the magnet clamp of the magnet clamp system. [Figure 3] FIG. 3 is a partially enlarged view showing the device for preventing the object from falling off of the magnetic clamp system, showing a state in which a link chain is attached to the device for preventing the object from falling off. [Figure 4] FIG. 4 is a view similar to FIG. 3, showing a state in which the link chain has been released from the drop prevention device for the object to be sucked. [Figure 5] 5 is a perspective view showing the device for preventing the object from falling as shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] 1 to 5 show one embodiment of the present invention. In this embodiment, a magnetic clamp system is shown in which a magnetic clamp 3 and a device for preventing a mold (object to be attracted) from falling are applied to a horizontal injection molding machine equipped with a fixed platen (base) 1 and a movable platen (base) 2. First, the structure of the magnetic clamp system will be described with reference to FIG.

[0010] Magnetic clamps 3 are bolted to the side walls of the fixed platen 1 and the movable platen 2 (not shown), and a mold (object to be attracted) 4 is attracted to the magnetic clamps 3 by magnetic attraction. The magnetic clamps 3 on the fixed platen 1 side and the magnetic clamps 3 on the movable platen 2 side have almost the same configuration, and only the magnetic clamp 3 on the fixed platen 1 side is shown in Figure 1.

[0011] The magnetic clamp 3 is provided with a flat magnetic plate 5. The magnetic plate 5 is made of a magnetic material. An attraction surface 5a is formed on the left end wall of the magnetic plate 5, and the mold 4 is attracted and fixed to the attraction surface 5a.

[0012] As shown in Figure 2, which is a partially enlarged view of portion A in Figure 1, a mounting hole 6 is opened in the left end surface of magnet plate 5. A ring-shaped bobbin 7 is inserted into the mounting hole 6, and a coil 8 is wound around it multiple times. A cylindrical first magnet 10 is inserted into an inner peripheral hole 9 of bobbin 7, with its right end surface abutting against the bottom surface 6a of the mounting hole 6. In this embodiment, the first magnet 10 is made of an alnico magnet.

[0013] A plurality of second magnets 11 are mounted in the mounting hole 6 to the left of the left end face of the first magnet 10 (towards the attracting surface 5a of the magnet plate 5). The plurality of second magnets 11 form a substantially cylindrical shape, and are mounted with their outer circumferential surface abutting or close to the inner circumferential surface of the mounting hole 6. In this embodiment, the second magnets 11 are made of neodymium magnets.

[0014] The main body 12a of the cylindrical magnetic pole member 12 is inserted into the cylindrical hole of the second magnet 11 and fixed to the magnet plate 5 with bolts. The magnetic pole member 12 is made of a magnetic material. The right end face of the magnetic pole member 12 abuts against the first magnet 10, and the outer circumferential surface of the magnetic pole member 12 abuts against or is close to the second magnet 11. The flange portion 12b, which is the left end portion of the magnetic pole member 12, is formed with a larger diameter than the main body portion 12a of the magnetic pole member 12. The flange portion 12b abuts against or is close to the inner circumferential wall of the mounting hole 6. A sealing member 14 is attached to the annular space 13 formed between the flange portion 12b and the second magnet 11. The sealing member 14 prevents water, oil, and foreign matter from entering the mounting hole 6 from the outside.

[0015] 1 and 2, a communication hole (not shown) that straddles the mounting hole 6 and another adjacent mounting hole 6 is formed in the right wall of the magnet plate 5. The coil 8 is connected to another adjacent coil 8 through the communication hole by a wiring 15. The coil 8 is connected in series to a plurality of coils 8, and is ultimately connected to a control device 16 via the wiring 15.

[0016] The control device 16 is composed of a computer including a CPU, ROM, and RAM, a power supply unit (not shown), and other components that supply power to the coil 8. The control device 16 switches the magnetic clamp 3 between a state in which the mold 4 is attracted and a state in which the mold 4 is released from the attraction. More specifically, when the control device 16 energizes the coil 8 in a predetermined direction (forward direction) for several seconds, the magnetic flux direction of the first magnet 10 becomes the same as the magnetic flux direction of the second magnet 11. This generates magnetic flux between the mold 4 and the magnet plate 5, and the mold 4 is fixed to the attraction surface 5a of the magnet plate 5. On the other hand, when the control device 16 energizes the coil 8 in the opposite direction from the forward direction for several seconds, the polarity of the first magnet 10 is reversed, and the magnetic flux direction of the first magnet 10 becomes opposite to the magnetic flux direction of the second magnet 11. This generates magnetic flux only inside the magnet plate 5, and the magnetic flux is demagnetized between the mold 4 and the magnet plate 5. As a result, the mold 4 is separated from the attraction surface 5a of the magnet plate 5.

[0017] One end 19a of a link chain 19 is connected to the top of the mold 4 via an eyebolt 17 and a coupling 18. The link chain 19 is composed of a plurality of links 20, each made of linear iron wire formed into an oval shape. One link 20a of the plurality of links 20 is connected to a link 20b on the mold side and another link 20c. Within the inner peripheral hole of link 20a, the link 20b on the mold side and the other link 20c are each rotatable and movable. The other end 19b of the link chain 19 is detachably attached to a connecting mechanism C provided on the top of the fixed platen 1 (movable platen 2).

[0018] The connecting mechanism C is installed at a position higher than the position where one end 19a of the link chain 19 is connected to the mold 4. As shown in FIGS. 1 and 3 to 5, the connecting mechanism C includes a block 21 serving as a base, which is bolted to the upper end surface of the magnet plate 5. A mounting groove 22 is formed in the block 21 in a direction from the attracting surface 5a side to the back surface side. The mounting groove 22 opens on the front surface of the block 21 on the attracting surface 5a side, the back surface of the front surface, and the top surface. As shown in FIGS. 4 and 5, the mounting groove 22 includes, in order from the attracting surface 5a side to the back surface side, a first large groove 23 having a large width, a small groove 24 having a width smaller than that of the first large groove 23, and a second large groove 25 having a shape symmetrical to the first large groove 23 across the small groove 24. The first large groove 23 and the second large groove 25 have the same depth. The small groove 24 is shallower than the first large groove 23. In this embodiment, the first large groove 23 and the second large groove 25 are formed in a substantially trapezoidal shape in a plan view.

[0019] An attachment link 20a, which is one of the multiple links 20 of the link chain 19, can be inserted into the small groove 24 of the attachment groove 22. The attachment link 20a is inserted into the small groove 24 so that its inner circumferential hole faces horizontally and the longitudinal direction of the oval-shaped attachment link 20a faces horizontally. As shown in FIG. 3, the base end (the side closer to the mold 4) of the attachment link 20a in the longitudinal direction protrudes into the first large groove 23, and the tip end (the side farther from the mold 4) protrudes into the second large groove 25. Furthermore, a link 20b connected to the base end of the attachment link 20a is inserted into the first large groove 23 so that its inner circumferential hole faces vertically. The tip end of the link 20b can abut against the front wall surface 26 formed between the inner wall surface of the first large groove 23 and the inner wall surface of the small groove 24. A retaining link 20c is connected to the tip end of the attachment link 20a. The base end of the retaining link 20c can come into contact with the back wall surface 27 formed between the inner wall surface of the second large groove 25 and the inner wall surface of the small groove 24. As a result, even if the link chain 19 attached to the attachment groove 22 is pushed or pulled horizontally, the tip end of the link 20b will be received by the front wall surface 26, or the base end of the retaining link 20c will be received by the back wall surface 27.

[0020] In this embodiment, the rear wall surface 27 is inclined relative to the vertical direction so that it moves away from the attraction surface 5a as it extends upward. In the connecting mechanism C of this embodiment, the inclination angle is set to 2°, but is not limited to this and may be set to 1° to 15°. Because the rear wall surface 27 is inclined, the magnetic attraction force of the magnetic clamp 3 may decrease for some reason, causing the mold 4 to come off the magnetic plate 5 and fall. In this case, the link chain 19 is pulled leftward, causing the retaining link 20c to push the inclined rear wall surface 27. The resulting reaction force acts from the rear wall surface 27 on the retaining link 20c toward the lower right, which in turn pushes the mounting link 20a toward the lower right. This pushes the mounting link 20a toward the bottom wall of the mounting groove 22, making it difficult for the link chain 20 to come off the mounting groove 22. As a result, the mold 4 is received by the magnetic plate 5 via the link chain 19 and the block 21, preventing it from falling to the floor.

[0021] A hole is opened in the bottom surface of the second large groove 25 of the mounting groove 22, and a proximity sensor (detector) 28 is attached to the hole. The proximity sensor 28 detects the attachment link 20a of the link chain 19 inserted into the mounting groove 22. The detection result is transmitted as an electrical signal to the control device 16 and stored in the memory unit of the control device 16. When the operator operates the control device 16 to start the molding operation of the molding machine, the determination unit of the control device 16 checks the detection result to determine whether the link chain 19 is inserted into the mounting groove 22. If the detection result indicates that the link chain 19 is inserted into the mounting groove 22, the determination unit of the control device 16 determines that the molding machine is ready to proceed to the next process, for example, a process of driving the mold to open and close. If the detection result indicates that the link chain 19 is not inserted into the mounting groove 22, the determination unit of the control device 16 determines that the molding machine is not ready to proceed to the next process, for example, a process of driving the mold to open and close. Furthermore, when the determining unit determines that the link chain 19 is not attached to the attachment groove 22 of the block 21, the control device 16 notifies the worker of an abnormal state, for example, an abnormal state in which the molding operation is about to start without the link chain 19 being attached, by sounding an alarm buzzer or alarm lamp (neither of which are shown), displaying an alarm on a display, etc. Furthermore, when the detection result indicates that the link chain 19 is not inserted into the attachment groove 22, the control device 16 may prohibit the process from proceeding to the next step.

[0022] The above embodiment has the following advantages. Simply by inserting the attachment link 20a of the link chain 19 into the attachment groove 22 of the block 21 of the connecting mechanism C, the mold 4 can be reliably prevented from falling off the magnet plate 5. Furthermore, the detector 28 can reliably detect that the link chain 19 has been attached to the attachment groove 22. The detection result of the detector 28 is transmitted to the control device 16, allowing the judgment section of the control device 16 to determine whether or not it is possible to proceed to the next process and detect an abnormality. This makes it possible to issue a warning or prevent the machine from proceeding to the next process if, for example, an operator forgets to attach the link chain 19 to the connecting mechanism C and attempts to operate a molding machine or the like. As a result, the mold can be prevented from falling to the floor and being damaged.

[0023] The above embodiments can be modified as follows. The above-mentioned magnetic clamp system may be applied to other devices, such as machine tools equipped with a workpiece fixing means, instead of being applied to an injection molding machine. In this case, the object to be attracted is not limited to the mold 4 shown as an example, but may also be a workpiece or the like. The above-mentioned magnetic clamp 3 may be an electromagnetic magnetic clamp instead of the exemplified permanent electromagnetic magnetic clamp. The above-mentioned connecting mechanism C may be attached to the upper part of the fixed platen 1 or the movable platen 2 instead of being attached to the upper part of the magnetic clamp 3 . The detector 28 may be a switch instead of a proximity sensor. A photosensor may be used instead of a proximity sensor. In this case, a light emitter of the photosensor is attached to a wall of the attachment groove 22, and a light receiver of the photosensor is attached to another wall opposite the wall of the attachment groove 22. Then, when the link 20a of the link chain 19 inserted into the attachment groove 22 blocks the light from the light emitter to the receiver, it is detected that the link chain 19 has been attached to the connecting mechanism. The transmission and reception of signals between the proximity sensor 28 and the control device 16 is not limited to the contact type using electrical contacts as exemplified above, but may be a contactless type using light, magnetism, radio waves, or the like. Of course, various other modifications can be made within the scope of what can be imagined by those skilled in the art. [Explanation of symbols]

[0024] C: Connection mechanism, 1: Base, 2: Base, 3: Magnetic clamp, 4: Object to be attracted, 5a: Attraction surface, 19: Link chain, 19a: Base end, 19b: Tip end, 20: Link, 20a: Mounting link, 20c: Anti-slip link, 21: Block, 22: Mounting groove, 26: Front wall, 27: Back wall, 28: Detector.

Claims

1. an object to be attracted (4) that is magnetically attracted to an attraction surface (5a) of a magnetic clamp (3) provided on a side wall of the base (1, 2); a link chain (19) having a base end (19a) attached to the object to be attracted (4), the link chain (19) being configured by a series of multiple links (20); a connecting mechanism (C) attached to an upper portion of the magnetic clamp (3) or the base (1, 2), the connecting mechanism (C) detachably connecting the tip end (19b) of the link chain (19) to the magnetic clamp (3) or the base (1, 2); an attachment groove (22) provided on an upper portion of the block (21) of the connecting mechanism (C) and into which an attachment link (20a), which is one of the plurality of links (20), can be inserted; a detector (28) fixed to a hole opened in a wall surface constituting the mounting groove (22), the detector (28) detecting that the mounting link (20a) has been mounted in the mounting groove (22).

2. 2. The device for preventing an object from falling according to claim 1, The wall surface of the block (21) is formed such that a back wall surface (27) opposite to a front wall surface (26) on the adsorption surface (5a) side is inclined with respect to the vertical direction so as to move away from the adsorption surface (5a) as it goes upward, A device for preventing objects from falling, characterized in that a stop link (20c) connected to the tip side of the attachment link (20a) is capable of abutting against the back wall surface (27).

Images