JP2022104764A - Projection-welding electrode with magnet - Google Patents

Abstract

To actively cool a permanent magnet and a magnet force transmission member by air, and to prevent the intrusion of scattered impurities from a welded part.SOLUTION: In an electrode 5 having a cylindrical main body 6 and an end lid 10 attached to an end part of the main body 6, and having a through-hole 19 of a component, a small-diameter hole 18 communicating with the through-hole 19 and a large-diameter hole 17 larger than the small-diameter part 18 in a diameter are formed at a part of the electrode 5, a vessel 14 accommodated with a permanent magnet 15 is inserted into the large-diameter hole 17, a magnetic force transmission member 16 extending from the vessel 14 is inserted into the small-diameter hole 18, a first air passage 42 formed at the vessel 14, a second air passage 43 formed at the magnetic force transmission member 16 and a communication air passage 44 for making the first air passage 42 and the second air passage 43 communicate with each other at a boundary part between the large-diameter hole 17 and the small-diameter hole 18 are arranged, and cooling air circulates to the second passage 43 from the first air passage 42 through the communication air passage 44.SELECTED DRAWING: Figure 1

Description

The present invention relates to projection welding electrodes incorporating permanent magnets.

In Japanese Patent No. 6736016, a container containing a permanent magnet and a magnetic force transmitting member extending from the container are supported in a slidable state in the electrode, and the permanent magnet is cooled by a water cooling method. It is also described that the component inserted into the through hole of the electrode is attracted by a permanent magnet.

Patent No. 6736016 Patent specification

In the technique described in the above patent document, the permanent magnet is cooled by the cooling water through the heat insulating guide cylinder made of the insulating material, so that it is necessary to carefully manage the flow of the cooling water so as not to cause insufficient cooling. There is. Further, in the invention described in the above patent document, there is a problem that scattered impurities such as spatter cannot be completely prevented from entering the electrode.

The present invention solves the above-mentioned problems, and actively cools a container containing a permanent magnet and a magnetic force transmitting member extending from the container by an air cooling method, and also disperses impurities from a molten portion. The purpose is to prevent the invasion of.

The invention according to claim 1 is
A cylindrical metal body and a metal end lid having a through hole attached to the end of the body and into which a component is inserted form a main component to form an electrode.
A small-diameter hole communicating with the through hole and a large-diameter hole having a larger diameter than the small-diameter hole are provided in a part of the electrode in a state of being coaxial with the central axis of the electrode.
A container containing a permanent magnet is inserted into the large-diameter hole in a slidable state.
A magnetic force transmitting member extending from the container is inserted into the small diameter hole in a slidable state.
The first air passage formed along the outer peripheral portion of the container, the second air passage formed along the outer peripheral portion of the magnetic force transmitting member, and the first at the boundary between the large-diameter hole and the small-diameter hole. A communication air passage that connects one air passage and the second air passage is provided.
The cooling air supplied to the large-diameter hole from the first air passage passes through the communicating air passage, depending on the temperature state of the permanent magnet due to the number of weldings and the state such as the scattering of impurities from the molten portion. It is a projection welding electrode with a magnet, which is configured to flow to a second air passage.

The first air passage formed along the outer peripheral portion of the container, the second air passage formed along the outer peripheral portion of the magnetic force transmitting member, and the first air passage and the first air passage at the boundary between the large-diameter hole and the small-diameter hole. 2 A communication air passage that communicates with the air passage is provided, and the cooling air sent to the large-diameter hole is described according to the temperature state of the permanent magnet due to the number of weldings and the state of impurities scattered from the molten part. It is circulated from the 1 air passage to the 2nd air passage via the communicating air passage.

When the number of weldings per unit time increases, the permanent magnet becomes overheated and the attractive magnetic force of the permanent magnet decreases. As described above, by circulating the cooling air from the first air passage to the second air passage through the communicating air passage, the overheated state of the permanent magnet is eliminated, and the permanent magnet is demagnetized to the temperature of the component. The problem that the suction power is reduced is solved. As one of the heat flows of the heat of fusion, heat is transferred from a component inserted in the through hole to a permanent magnet via a magnetic force transmitting member. When the cooling air passes through the second air passage, the magnetic force transmission member is cooled, so that the overheated state of the permanent magnet due to the heat flow can be eliminated. Since the cooling air flows through the first air passage, the communicating air passage, and the second air passage at once without interruption, it is effective in enhancing the cooling effect.

When a permanent magnet is heated to an abnormally high temperature, the decrease in magnetic force does not recover even when it returns to room temperature. Abnormal overheating of the permanent magnet is prevented, which is effective for improving the durability of the permanent magnet.

Since the magnetic force transmitting member extending from the container is inserted into the small diameter hole in a slidable state, the attractive force to the component decreases while the magnetic force lines of the permanent magnet pass through the magnetic force transmitting member. If the suction force is reduced by the temperature demagnetization phenomenon before such a decrease in the suction force, the suction holding force of the component is significantly reduced. In the present invention, since the permanent magnet is positively cooled by the cooling air, there is no concern that the suction holding force is lowered as described above.

Due to the cooling phenomenon as described above, the abnormally high temperature of the permanent magnet can be prevented. Usually, various permanent magnets such as a ferrite magnet, a neodymium magnet, a samakova magnet, and an alnico magnet are adopted, but a magnet having less thermal demagnetization is preferably used. Even with a permanent magnet that has 100% attractive force at an outside temperature of 20 degrees, the attractive force reduction varies depending on the type of magnet, but when it is heated by the heat of fusion and the permanent magnet reaches 50 degrees, the attractive force is reduced by 10%. Or, when it reaches 100 degrees, the suction force is reduced by 20%. When such temperature demagnetization occurs in the permanent magnet itself, the attractive force attenuation in the process of transmitting the attractive force in the magnetic force transmitting member is added, which greatly affects the attractive holding force of the component, and in an extreme case, the component. There is a concern that the magnet will fall, but in the present invention, the abnormal overheating of the permanent magnet is suppressed, so that the above problem is solved.

The first air passage is formed along the outer peripheral portion of the container, the second air passage is formed along the outer peripheral portion of the magnetic force transmission member, and the communication air passage is formed at the boundary between the large diameter hole and the small diameter hole. Therefore, the cooling action is performed at the location closest to the permanent magnet, so that a higher cooling effect can be obtained.

When actually flowing cooling air from the first air passage to the second air passage via the communicating air passage, the temperature state of the permanent magnet is detected, and the start time of the air flow, the air flow rate, the air flow time, etc. It can be easily carried out by adjusting the above. Further, in order to prevent spatter, which is a scattered impurity, and molten vaporization gas of galvanized steel sheet from entering the through holes and small diameter holes, it is desirable to allow cooling air to flow for each welding. These cooling air flow controls combine a sensor that detects the temperature of the permanent magnet and the energization of the electrodes and emits a signal, a control device that processes the signal from the sensor, and an air supply control valve that operates with the signal from the control device. This makes it easy to implement. At the same time, it becomes possible to control the supply of cooling air that appropriately adapts to the temperature state of the permanent magnet. The reason why the flow control of the cooling air can be controlled by the control signal from such a control device is that the cooling air is circulated without interruption from the first air passage to the second air passage via the communicating air passage. Has become an indispensable and important entity.

Since the magnetic force transmitting member extending from the container is inserted into the small diameter hole in a slidable state, the attractive force to the component decreases while the magnetic force lines of the permanent magnet pass through the magnetic force transmitting member. If the suction force is reduced by the temperature demagnetization phenomenon before such a decrease in the suction force, the suction holding force of the component is significantly reduced. In the present invention, the overheating of the permanent magnet is positively suppressed by the cooling air flowing from the first air passage to the second air passage through the communicating air passage, so that there is no concern about the decrease in suction holding force as described above. ..

The invention of the present application is the invention of the electrode as described above, but as is clear from the examples described below, it can exist as a method invention that specifies the flow behavior of the cooling air, the heat flow, and the like.

It is a cross-sectional view of the whole electrode and the cross-sectional view of each part. It is sectional drawing of each part which shows the other deformation example. It is sectional drawing which shows the other embodiment.

Next, a mode for carrying out the projection welding electrode with a magnet of the present invention will be described.

1 and 2 show Example 1 of the present invention.

First, the parts handled by the electrodes of the first embodiment will be described.

As the parts, there are various parts such as a shaft-shaped member with a flange and a rod-shaped part. Here, it is an iron projection bolt 1, a shaft portion 2 on which a male screw is formed, a circular flange 3 arranged coaxially with the shaft portion 2, and a conical welding projection provided at the center of the flange 3. It is composed of 4.

Hereinafter, in the present specification and claims, the projection bolt may be simply referred to as a bolt.

Next, the main body of the electrode will be described.

The entire electrode is indicated by reference numeral 5. The main body 6 of the electrode is made of a cylindrical metal, and a fixed side member 8 made of chrome copper is connected to the welding side member 7 made of chrome copper via a screw portion 9. A beryllium copper end lid 10 is attached to the tip of the weld side member 7 in a detachable state by a screw portion 11. Reference numeral 10a indicates an insulating cylinder fitted in the through hole 19 of the end lid 10. A cooling hole 13 is provided at the end of the fixed side member 8.

As described above, the electrode 5 is configured such that the main body 6 and the end lid 10 are the main constituent members. Further, in the first embodiment, the heat insulating guide cylinder 12 described later is also a main constituent member.

The electrode 5 may be either a movable electrode or a fixed electrode, but is referred to as a movable electrode here. Further, the illustration of the fixed electrode of the other party on which the steel plate component is placed is omitted.

Next, the heat insulating guide tube will be described.

A cylindrical heat insulating guide cylinder 12 is inserted inside the main body 6 having a circular cross section. The heat insulating guide cylinder 12 is made of an insulating material such as bakelite, polyamide resin, or PTFE. The heat insulating guide cylinder 12 is formed with a small-diameter hole 18 communicating with the through hole 19 of the end lid 10 and a large-diameter hole 17 having a larger diameter than the small-diameter hole 18 communicating with each other. The small-diameter hole 18 and the large-diameter hole 17 are arranged in a part of the electrode 5 in a coaxial state with the central axis OO of the electrode 5 in this way.

A container 14 accommodating a permanent magnet 15 is inserted into the large-diameter hole 17 in a slidable state. The container 14 is made of stainless steel, which is a cup-shaped non-magnetic material with a circular cross section. An iron magnetic force transmitting member 16 welded to the container 14 is inserted into the small diameter hole 18 in a slidable state. The magnetic force transmitting member 16 is a rod-shaped member having a circular cross section, is in close contact with the permanent magnet 15, and is attracted to the end portion of the shaft portion 2 inserted into the through hole 19. The inner diameter of the through hole 19 is the same as the inner diameter of the insulating cylinder 10a, and a slight gap is formed between the inner diameter and the shaft portion 2. As described above, the small-diameter hole 18 and the large-diameter hole 17 are arranged coaxially with the central axis OO of the electrode 5.

The small-diameter hole 18 and the large-diameter hole 17 in the present invention are provided in a part of the electrode 5. Therefore, in the first embodiment, both holes 17 and 18 are formed in the heat insulating guide cylinder 12 corresponding to a part of the electrode 5.

Next, the energization structure will be described.

A storage hole 20 communicating with the large diameter hole 17 of the heat insulating guide cylinder 12 is opened in the fixed side member 8, and a circular insulating sheet 22 made of an insulating material is sealed in the inner ceiling portion thereof, and the inside thereof is electrically connected. The washer 23 is fitted. A compression coil spring 24 is interposed between the conductive washer 23 and the container 14, and the tension thereof is received by the inner end surface 25 of the large-diameter hole 17 shown in FIG. 1 (E) via the container 14.

A conduction wire 26 is connected to the conduction washer 23 and is led to the outside through the inside of the insulating pipe 27. The other copper wire 28 is connected to the fixed side member 8 which is the main body 6. These copper wires 26 and 28 are connected to the detection device 29.

Next, the bolt supply means will be described.

In order to insert the shaft portion 2 of the bolt 1 into the through hole 19 to reach the magnetic force transmission member 16, the operator may manually insert the bolt 1, but here, the stainless steel supply rod 30 is used. Illustrated. The supply rod 30 is made to perform a square motion as shown by arrows 31, 32, 33. A recess 34 having an open tip side is formed at the tip of the supply rod 30, and a flange 3 is accepted therein, and a permanent magnet 35 is embedded in the tip to stabilize the upright holding of the bolt 1.

Next, the cooling water passage will be described.

A cooling water passage 38 is provided on the outer peripheral portion of the heat insulating guide cylinder 12 in a form in which an annular groove 37 is formed in the circumferential direction. It is illustrated in FIG. 1 (B) in an easy-to-understand manner. The annular groove 37 is brought closer to the heat source, that is, the side closer to the end lid 10 when viewed in the direction of the central axis OO. That is, the annular groove 37 is formed at a position close to the end lid 10 side from the center of the axial length of the heat insulating guide cylinder 12.

The portion of the heat insulating guide cylinder 12 on the OO side of the central axis of the cooling water passage 38 is the heat insulating portion 39. The above-mentioned container 14 is inserted inside the heat insulating portion 39 in a slidable state. Therefore, the permanent magnet 15, the heat insulating portion 39, and the cooling water passage 38 are arranged side by side in the radial direction of the main body 6.

The cooling water passage 38 is provided with an inlet 40 and an outlet 41 for supplying and discharging cooling water. As is clear from FIG. 1 (B), the metal water pipe 21 is coupled to the weld side member 7 to form the inlet 40 and the outlet 41, and both ports 40 and 41 are aligned on the diameter line. Further, it is open at the center position of the cooling water passage 38 as seen in the direction of the central axis OO. The water pipe 21 is welded to the weld side member 7 as shown in the figure, or is screwed in. Although not shown, a water pipe made of synthetic resin is connected to the water pipe 21.

Next, the heat insulating portion will be described.

The heat flow in which the heat of fusion during welding is transferred to the permanent magnet 15 is mainly transferred from the end lid 10 to the welding side member 7, transmitted to the heat insulating portion 39 via the high-temperature cooling water, and is transmitted from the container 14 to the permanent magnet. Up to 15. In such a heat flow path, it is advantageous to combine the cooling with the cooling water described above and the heat insulation in the heat insulating portion 39. Further, there is a heat flow transferred from the shaft portion 2 to the permanent magnet 15 via the magnetic force transmission member 16, and the present invention effectively works to suppress this heat flow.

Next, other detailed structures will be described.

In order to prevent leakage of cooling water, an O-ring 45 is arranged between the heat insulating guide cylinder 12 and the inner surface of the welding side member 7. As shown in FIG. 1A, the O-ring 45 is fitted into a groove in the circumferential direction formed in the heat insulating guide cylinder 12.

The shaft portion 2 of the bolt 1 is inserted into the through hole 19, and the electrode 5 advances in a state where the upper end of the shaft portion 2 is attracted to the magnetic force transmission member 16, and a steel plate component on the other fixed electrode (not shown). The welding projection 4 is pressurized. As a result, the compression coil spring 24 is compressed and the flange 3 comes into close contact with the end lid 10. Due to this close contact, the copper wire 26 and the conductive washer 23. A detection current circuit consisting of a compression coil spring 24, a container 14, a magnetic force transmission member 16, a bolt 1, and an end lid 10 is established, and it is confirmed by the detection device 29 that the bolt 1 is normally positioned, and then it is movable. The advance movement of the electrode is started.

If the bolt 1 is not inserted into the through hole 19 and the electrode 5 advances and the end lid 10 is pressed against the steel plate component, the detection current circuit as described above is not formed. Therefore, in the detection device 29, the bolt Absence is determined, an abnormality alarm is displayed, and electrode advancement is prohibited.

Next, the passage structure of the cooling air will be described.

In the case shown in FIG. 1, a first air passage 42, a second air passage 43, and a communication air passage 44 are formed at the boundary between the container 14, the magnetic force transmitting member 16, and the large diameter hole 17 and the small diameter hole 18. Has been done.

As shown in FIG. 1 (B), the first air passage 42 is formed by cutting the outer peripheral surface of a container 14 having a circular cross section to provide a flat surface 46, and is provided between the flat surface 46 and the large-diameter hole 17. The formed space is the first air passage 42. As shown in the figure, four first air passages 42 having such a structure are provided. In other words, the first air passage 42 is formed along the outer peripheral portion of the container 14. Looking at the cross section of the first air passage 42, the inner surface of the passage 42 is an arc surface of a flat surface 46 and a large-diameter hole 17, and is configured in the central axis OO direction.

On the other hand, a concave groove 47 is formed on the outer peripheral surface of the magnetic force transmitting member 16 having a circular cross section in the direction of the central axis OO, and four second air passages 43 are provided as shown in FIG. 1 (C). .. Here, the concave groove shape is adopted to increase the flow path area, but if necessary, the concave groove can be formed into a flat cut form like the first air passage 42. In other words, the second air passage 43 is formed along the outer peripheral portion of the magnetic force transmitting member 16. Looking at the cross section of the second air passage 43, the inner surface of the passage 43 is the inner surface of the concave groove 47 and the arc surface of the small diameter hole 18, and is configured in the central axis OO direction. It is configured.

At the boundary between the large-diameter hole 17 and the small-diameter hole 18, a communication air passage 49 that communicates the first air passage 42 and the second air passage 43 is provided. As shown in FIG. 1 (D), the communication air passage 49 is formed by forming the communication groove 50 between the flat surface 46 forming the first air passage 42 and the concave groove 47 forming the second air passage 43. It is formed. A flat stepped surface 51 is formed at the boundary between the small diameter magnetic force transmitting member 16 and the large diameter container 14, and the stepped surface 51 is pressed against the inner end surface 25 by the tension of the compression coil spring 24. .. The step surface 51 and the inner end surface 25 exist on a virtual plane perpendicular to the central axis OO.

A communication air passage 44 is formed at the boundary between the large-diameter hole 17 and the small-diameter hole 18, but in the case shown in FIG. 1, the container 14 and the magnetic force transmission member 16 are processed into a single component integrated. The first air passage 42, the second air passage 43, and the communication air passage 44 are all formed, and the large-diameter hole 17, the small-diameter hole 18 side, and the stepped structure portion between the both holes 17, 18 (inner end surface 25, (See FIG. 1 (E)) is not specially processed.

A cooling air supply hole 56 is opened in the fixed side member 8, and a supply pipe 57 is joined there by welding or the like. An air hose 59 extending from the air supply control valve 58 is joined to the supply pipe 57. The cooling air supplied from the supply hole 56 passes through the first air passage 42, the communication air passage 49, and the second air passage 43.

Next, a modification of the cooling air passage structure will be described.

FIG. 2 shows a modified example of the air passage structure. This modification is an example in which the heat insulating guide cylinder 12 side is processed and the container 14 and the magnetic force transmission member 16 side are not processed at all.

2 (A) is a cross-sectional view corresponding to the BB cross section of FIG. 1, and FIG. 2 (B) is a cross-sectional view corresponding to the CC cross section of FIG.

That is, the first air passage 42 is formed on the inner surface of the large-diameter hole 17 by the concave groove 53 formed in the central axis OO direction, and the concave groove 54 formed on the inner surface of the small-diameter hole 18 in the central axis OO direction. The second air passage 43 is formed, and the communication air passage 49 is formed by the communication groove 55 provided on the inner end surface 25. The first air passage 42, the second air passage 43, and the communication air passage 49 are provided by four each.

In other words, the first air passage 42 is formed along the outer peripheral portion of the container 14. Looking at the cross section of the first air passage 42, the inner surface of the passage 42 is composed of the inner surface of the concave groove 53 and the outer peripheral surface of the container 14. In other words, the second air passage 43 is formed along the outer peripheral portion of the magnetic force transmitting member 16. Looking at the cross section of the second air passage 43, the inner surface of the passage 43 is composed of the inner surface of the concave groove 54 and the outer peripheral surface of the magnetic force transmitting member 16.

Next, the supply control of the cooling air will be described.

The supply control of the cooling air is performed according to the temperature state of the permanent magnet according to the number of weldings and the state such as the scattering of impurities from the molten portion. Various control methods can be adopted, but here, a general method in which a temperature sensor, a control device, or the like is combined is adopted.

In FIG. 1, a signal from a sensor 61 for measuring the temperature of a permanent magnet 15 is transmitted to a control device 60 composed of a sequence circuit and a simple computer device. The sensor 61 is attached to the outer peripheral surface of the main body 6 and detects whether or not the permanent magnet 15 has an abnormally high temperature. The temperature of the permanent magnet 15 and the temperature of the outer peripheral surface of the main body 6 are proportional to each other. Further, a sensor 62 that transmits each pressure stroke of the electrode 5 is arranged. The sensor 62 transmits a signal for each pressurization stroke to the control device 60 by attaching the advancing / retreating driving means of the electrode 5, for example, an air cylinder (not shown). It is also possible to substitute the detection device 29 with a part of the control device 60. The signals from the sensors 61 and 62 are processed by the control device 60, and the operation signal is transmitted to the air supply control valve 62.

When the number of weldings increases due to the production quantity or the like, the temperature of the permanent magnet 15 becomes overheated, so that the temperature state is detected by the sensor 61 and the signal is sent to the control device 60. As a result, even when the electrode 5 is retracted, cooling air is supplied to the large diameter hole 17, and a series of air flows through the first air passage 42, the communicating air passage 49, and the second air passage 43 for a long time. It is formed over and becomes a state where the cooling property is improved. Further, a series of air flows passing through the first air passage 42, the communicating air passage 49, and the second air passage 43 are formed by the signal transmitted from the sensor 62 for each pressurization stroke of the electrode 5. It prevents spatter scattered from the molten portion and the vaporized gas of zinc plating applied to the steel plate from entering the through hole 19.

In the example shown in FIG. 1, the first air passage 42 is formed of a flat surface 46, but it is also possible to form the first air passage 42 in a shape like a concave groove 47 to form an air passage. Further, although the second air passage is composed of the concave groove 47, it is also possible to form the air passage by making it into a shape like a flat surface 46. Further, it is also possible to communicate the first air passage 42 and the second air passage 43 shown in FIG. 1 by forming a communication groove 55 in the inner end surface 25 shown in FIG. 2. Further, it is also possible to make three passages 42, 43 and 44 according to the temperature state of the electrode 5.

The effects of Example 1 described above are as follows.

At the boundary between the large-diameter hole 17 and the small-diameter hole 18, the first air passage 42 formed along the outer peripheral portion of the container 14, the second air passage 43 formed along the outer peripheral portion of the magnetic force transmission member 16. A communication air passage 44 that connects the first air passage 42 and the second air passage 43 is provided, and a large-diameter hole is provided according to the temperature state of the permanent magnet 15 according to the number of weldings and the state of impurities scattered from the molten portion. The cooling air supplied to 17 is circulated from the first air passage 42 to the second air passage 43 via the communication air passage 44.

When the number of weldings per unit time increases, the permanent magnet 15 becomes overheated and the attractive magnetic force of the permanent magnet 15 decreases. As described above, by flowing the cooling air from the first air passage 42 to the second air passage 43 via the communicating air passage 44, the overheated state of the permanent magnet 15 is eliminated and the permanent magnet 15 is demagnetized. Therefore, the problem that the suction force to the bolt 1 is reduced is solved. As one of the heat flows of the heat of fusion, heat is transferred from the bolt 1 inserted in the through hole 19 to the permanent magnet 15 via the magnetic force transmission member 16. When the cooling air passes through the second air passage 43, the magnetic force transmission member 16 is cooled, so that the overheated state of the permanent magnet 15 due to the heat flow can be eliminated. Since the cooling air flows through the first air passage 42, the communication air passage 44, and the second air passage 43 at once without interruption, it is effective in enhancing the cooling effect.

When the permanent magnet 15 is heated to an abnormally high temperature, the decrease in magnetic force does not recover even when it returns to room temperature. , Abnormal overheating of the permanent magnet is prevented, which is effective for improving the durability of the permanent magnet.

Since the magnetic force transmitting member 16 extending from the container 14 is inserted into the small diameter hole 18 in a slidable state, an attractive force is applied to the bolt 1 while the magnetic force lines of the permanent magnet 15 pass through the magnetic force transmitting member 16. descend. If the suction force is reduced due to the temperature demagnetization phenomenon before such a decrease in the suction force, the suction holding force of the bolt 1 is significantly reduced. In this embodiment, since the permanent magnet 15 is positively cooled by the cooling air, there is no concern that the suction holding force is lowered as described above.

Due to the cooling phenomenon as described above, the abnormally high temperature of the permanent magnet 15 can be prevented. Usually, various magnets such as a ferrite magnet, a neodymium magnet, a samakova magnet, and an alnico magnet are adopted as the permanent magnet 15, but a magnet having less thermal demagnetization is preferably used. Even with a permanent magnet that has 100% attractive force at an outside temperature of 20 degrees, the attractive force reduction varies depending on the type of magnet, but when it is heated by the heat of fusion and the permanent magnet reaches 50 degrees, the attractive force is reduced by 10%. Or, when it reaches 100 degrees, the suction force is reduced by 20%. When such temperature demagnetization occurs in the permanent magnet 15 itself, the attractive force attenuation in the process of transmitting the attractive force in the magnetic force transmitting member 16 is added, which greatly affects the attractive holding force of the bolt 1, and in an extreme case. There is a concern that the bolt 1 will fall, but in this embodiment, the abnormal overheating of the permanent magnet 15 is suppressed, so that the above problem is solved.

The first air passage 42 is formed along the outer peripheral portion of the container 14, the second air passage 43 is formed along the outer peripheral portion of the magnetic force transmission member 16, and the communication air passage 44 has a large diameter hole 17 and a small diameter. Since it is formed at the boundary portion of the hole 18, the cooling action is performed at the position closest to the permanent magnet 15, so that a higher cooling effect can be obtained.

When cooling air is actually circulated from the first air passage 42 to the second air passage 43 via the communicating air passage 44, the temperature bear of the permanent magnet 15 is detected, and the start time of the air flow and the air flow rate. , It can be easily carried out by adjusting the air circulation time and the like. Further, in order to prevent spatter, which is a scattered impurity, and molten vaporized gas of galvanized steel sheet from entering the through hole 19 and the small diameter hole 18, it is desirable to allow cooling air to flow for each welding. These cooling air flow controls are performed by a sensor (detection device 29) that detects the temperature of the permanent magnet 15 and electrode energization and emits a signal, a control device 60 that processes signals from the sensors 61 and 62, and a control device 60. It can be easily carried out by combining an air supply control valve 58 or the like that operates by a signal. It is possible to control the flow of the cooling air by the control signal from the control device 60, that the cooling air flows from the first air passage 42 to the second air passage 43 via the communicating air passage 44 without interruption. Being indispensable and important.

Since the magnetic force transmitting member 16 extending from the container 14 is inserted into the small diameter hole 18 in a slidable state, an attractive force is applied to the bolt 1 while the magnetic force lines of the permanent magnet 15 pass through the magnetic force transmitting member 16. descend. If the suction force is reduced due to the temperature demagnetization phenomenon before such a decrease in the suction force, the suction holding force of the bolt 1 is significantly reduced. In this embodiment, the overheating of the permanent magnet 15 is positively suppressed by the cooling air flowing from the first air passage 42 to the second air passage 43 via the communicating air passage 44, so that the suction holding force as described above is suppressed. There is no worry of deterioration.

Since the first air passage 42, the communicating air passage 44, and the second air passage 43 are always in a communicating state, the cooling air is interrupted by using the control device 60 or the air supply control valve 58 outside the electrode 5. Can be controlled. By performing such intermittent control, fine and precise cooling control can be performed according to the temperature state of the permanent magnet 15 and the state of spatter generation.

FIG. 3 shows Example 2 of the present invention.

In the present invention, a small-diameter hole 18 and a large-diameter hole 17 are provided in a part of the electrode 5 in a state coaxial with the central axis OO of the electrode, and the first air passage 42 is along the outer peripheral portion of the container 14. The second air passage 43 is formed along the outer peripheral portion of the magnetic force transmission member 16, and is provided with a communication air passage 44 that communicates the first air passage 42 and the second air passage 43. Against such a background, in the first embodiment, the cooling air circulates in contact with the container 14, the magnetic force transmitting member 16, and the heat insulating guide cylinder 12.

In the present invention, a small-diameter hole 18 and a large-diameter hole 17 are provided in a part of the electrode 5 in a state coaxial with the central axis OO of the electrode, and the first air passage 42 is along the outer peripheral portion of the container 14. The second air passage 43 is formed along the outer peripheral portion of the magnetic force transmission member 16, and is provided with a communication air passage 44 that communicates the first air passage 42 and the second air passage 43. Against such a background, in the second embodiment, the cooling air circulates in contact with the container 14, the magnetic force transmitting member 16, and the main body 6. That is, in the second embodiment, the above-mentioned heat insulating guide cylinder 12 is not adopted, and the large diameter hole 17 and the small diameter hole 18 are directly formed in the main body 6.

In this way, in the first embodiment, the large-diameter hole 17 and the small-diameter hole 18 are formed in the heat insulating guide cylinder 12, which is a member constituting a part of the electrode 5. Further, in the second embodiment, the large-diameter hole 17 and the small-diameter hole 18 are formed in the main body 6 which is a member constituting a part of the electrode 5.

Other than that, the configuration is the same as that of the first embodiment including the portion (not shown), and the same reference numerals are given to the members having the same function. The action and effect of Example 2 are the same as those of Example 1.

As described above, according to the electrode of the present invention, the container containing the permanent magnet and the magnetic force transmitting member extending from the container are positively cooled by an air cooling method, and the impurities scattered from the molten portion are removed. Prevent intrusion. Therefore, it can be used in a wide range of industrial fields such as a body welding process for automobiles and a sheet metal welding process for home electric appliances.

1 Projection bolt 2 Shaft 3 Flange 4 Welding protrusion 5 Electrode 6 Main body 7 Welding side member 8 Fixed side member 10 End lid 12 Insulation guide cylinder 14 Container 15 Permanent magnet 16 Magnetic force transmission member 17 Large diameter hole 18 Small diameter hole 19 Through hole 25 Inner end surface 38 Cooling water passage 40 Inlet 41 Exit 42 First air passage 43 Second air passage 44 Communication air passage 46 Flat surface 47 Concave groove 49 Communication air passage 50 Communication groove 51 Step surface 53 Concave groove 54 Concave groove 55 Communication groove 56 Supply hole 58 Air supply control valve 60 Control device 61 Sensor 62 Sensor OO Center axis

Claims (1)

A cylindrical metal body and a metal end lid having a through hole attached to the end of the body and into which a component is inserted form a main component to form an electrode.
A small-diameter hole communicating with the through hole and a large-diameter hole having a larger diameter than the small-diameter hole are provided in a part of the electrode in a state of being coaxial with the central axis of the electrode.
A container containing a permanent magnet is inserted into the large-diameter hole in a slidable state.
A magnetic force transmitting member extending from the container is inserted into the small diameter hole in a slidable state.
The first air passage formed along the outer peripheral portion of the container, the second air passage formed along the outer peripheral portion of the magnetic force transmitting member, and the first at the boundary between the large-diameter hole and the small-diameter hole. A communication air passage that connects one air passage and the second air passage is provided.
The cooling air supplied to the large-diameter hole from the first air passage passes through the communicating air passage according to the temperature state of the permanent magnet according to the number of welding times and the state such as the scattering of impurities from the molten portion. A projection welding electrode with a magnet, which is configured to flow to the second air passage.

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