JP2548966B2 - Movable yoke type lifting magnet - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a movable yoke type lifting magnet that lifts a plate-shaped work by an electromagnetic force, and in particular, a lifting magnet that can reliably lift the works one by one. Regarding

[Prior Art] A lifting magnet that lifts and conveys a plate-shaped work by electromagnetic force is known from Japanese Utility Model Publication No. 51-126570. This lifting magnet is used as a magnetic hand of an industrial robot, and is provided with a holder fixed to the tip of the robot arm. The holder is provided with a magnetic plate that is tiltably attached, and a large number of adsorption pieces arranged in a row at the lower end of the magnetic plate are held so as to be vertically movable.

In such a lifting magnet, since a large number of attraction pieces that come into contact with the work are movable up and down, even in the case of a large number of cylindrical works, for example, a large number of works can be attracted at the same time while preventing the work from rolling. can do.

FIG. 10 shows a movable yoke type lifting magnet that has been conventionally used by the applicant. In the figure, 1 indicates a main iron core, and a coil 2 is wound around the outer circumference of the main iron core 1. Both ends of the main iron core 1 extend in the vertical direction, and the main iron core 1
Movable yokes 3, 3'that are movable with respect to are located.
Workpieces 4 and 5 attracted by the lifting magnet are located directly below the movable yokes 3 and 3 '.
The distance L between the movable yoke 3 and the movable yoke 3'is set to be the same as the width of the main iron core 1, and is extremely large with respect to the plate thickness T of the work 4.

In such a movable yoke type lifting magnet, the magnetic flux φ generated by the coil 2 wound around the main iron core 1 passes through the main iron core 1, the movable yoke 3, the work 4, the movable yoke 3 ′, and the main iron core 1 in this order. To do. The attraction force due to the magnetic flux φ is generated on the contact surfaces 7, 7'of the movable yokes 3, 3'and the main iron core 1 and the contact surfaces 6, 6'of the movable yokes 3, 3'and the workpiece 4. , The movable yokes 3 and 3'are caused by the frictional force generated by the attraction between the movable yokes 3 and 3'and the main iron core 1.
The weight of 3'and the workpiece 4 is supported.

[Problems to be Solved by the Invention]

By the way, in a press processing line in an automobile manufacturing plant or the like, a thin steel plate (plate-shaped work) is automatically
It is required to take out the sheets one by one and supply them to the press machine. However, in the above-mentioned Japanese Utility Model Laid-Open No. 51-126570 and the lifting magnet shown in FIG. 10, if the attraction force is increased in order to ensure the attraction of the workpieces, two workpieces are stacked at the same time when a plurality of workpieces are stacked. There is a problem of adsorption. Therefore, in a press machine or the like, the plate thickness of the workpiece to be supplied is significantly increased with respect to the processing capacity, and the press machine may be damaged.

Generally, the distance between the work adsorbing parts (magnetic poles) of the movable yoke of the movable yoke type lifting magnet is shown in FIGS. 10 and 11.
As shown in the figure, since it is the same as the axial dimension of the main iron core 1, the distance L between the work adsorbing portions of both movable yokes 3 and 3'is 20 times or more the plate thickness T of the work 4, This causes a problem that two workpieces 4 and 5 are adsorbed at the same time. This is because when the magnetic flux φ passing through the movable yoke 3 passes between the contact surfaces 6 and 6 ', as shown in FIG.
Since the magnetic flux φ ′ passing through the upper workpiece 4 passes through the long distance L in contact with the lower workpiece 5, a part of the magnetic flux φ ′ (magnetic flux φ ″) easily enters the lower workpiece 5, and both workpieces 4, This is because a suction force is generated between the workpieces 5. When this suction force is large, the lower workpiece 5 is simultaneously lifted when the workpiece 4 is conveyed, and two workpieces are attracted.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a movable yoke type lifting magnet that can significantly reduce the attraction force generated between upper and lower works and can reliably lift the works one by one.

[Means for solving the problem]

A movable yoke-type lifting magnet according to the present invention which meets this object is provided with a plurality of vertically movable units arranged in opposition to each other so as to be attracted to a main iron core provided with a coil on the outer periphery. In a movable yoke type lifting magnet having a movable yoke, the distance between the workpiece adsorbing portions of the movable yokes facing each other is set to be approximately twice the plate thickness of the workpiece or less.

[Action]

In the movable yoke type lifting magnet configured as described above, when the distance between the workpiece attracting portions (magnetic poles) of the opposing movable yokes is set to about twice or less the plate thickness of the workpiece to be attracted, the magnetic flux is suddenly lowered. It becomes difficult to enter the work, and the suction force generated between the upper and lower works is significantly reduced as compared with the conventional structure. This is because when the magnetic flux passes through the magnetic body, it is distributed not as evenly distributed through the cross section of the magnetic path but as close as possible to the magnetic pole of the movable yoke. This is because the magnetic flux concentrates and passes through the work on the upper side in the state where the magnetic fluxes are arranged.

Therefore, the suction force generated between the upper and lower works does not cause the upper and lower works to be attracted to the movable yoke at the same time, and the works can be reliably lifted one by one.

〔Example〕

A preferred embodiment of a movable yoke type lifting magnet according to the present invention will be described below with reference to the drawings.

First Embodiment FIGS. 1 to 5 show a first embodiment of the present invention. In FIGS. 1 and 2, reference numeral 11 denotes a movable yoke type lifting magnet, and the lifting magnet 11 is connected to a conveyor (not shown). The lifting magnet 11 is composed of a main iron core 12, movable yokes 13 and 13 ', and a coil 14. Main iron core 12
Is composed of a soft magnetic material extending in the horizontal direction, and a coil 14 is wound around the outer peripheral surface of the main iron core 12. The movable yokes 13 and 13 'are located on both end surfaces of the main iron core 12, and can slide while contacting the main iron core 12. The movable yokes 13 and 13 'are made of a soft magnetic material that extends in the vertical direction. The lower portions of the movable yokes 13 and 13' extend once toward the center of the lifting magnet 11 and then downward from there. Is extended. The downwardly projecting portions are work adsorption portions (magnetic poles) 13a and 13'a that come into contact with the upper work 15.

A lead wire 20 is connected to the coil 14, and a predetermined voltage is applied to the coil 14 from a DC power supply 17 via a switch 18. The DC power supply 17 does not have to be a complete DC, and may be a pulsating voltage obtained by full-wave rectifying an AC.

Work 15 is a thin steel plate made of soft magnetic material.
A work 16 made of the same material as the work 15 is located below the 15 through a gap 19 formed by an oil film, foreign matter, and the like. Work suction parts 13a, 13'a of movable yokes 13, 13 '
The cross-sectional area of is smaller toward the tip. That is, each work suction portion 13a, the outer surface of 13a 'is an inclined surface, the width dimension D of the tip of each workpiece suction unit 13a, 13b is a 1.5 times the thickness T ₁ of the workpiece 15 There is. The inner side surfaces 13b and 13b 'of the respective work suction portions 13a and 13a' are vertical surfaces, and the distance L between the inner side surface 13b and the inner side surface 13b 'is L.
₁ is set in the vicinity of twice the plate thickness T ₁ of the workpiece 15 to be sucked.

 Next, the operation of the first embodiment will be described.

First, when a predetermined DC voltage is applied to the coil 14, a current flows through the coil 14 and a magnetic flux φ ₁ is generated. This magnetic flux φ
₁ passes through the main iron core 12, the movable yoke 13, the upper work 15, the movable yoke 13 ', and the main iron core 12 in this order. By the passage of the magnetic flux φ _1, an attraction force is generated on the contact surfaces 26, 26 ′, and the movable yokes 13, 13 ′ and the work 15 are attracted to each other. Similarly, a suction force is also generated on the contact surfaces 27 and 27 ', and the movable yoke
13, 13 'and the main iron core 12 are adsorbed. In this case, the lifting magnet 11 can lift the work 15 if an attractive force enough to support the weights of the movable yokes 13 and 13 'and the work 15 is generated on the contact surfaces 27 and 27'.

FIG. 3 schematically shows a magnetic flux passage path in the vicinity of the movable yoke in FIG. As shown in the figure,
When passing through the magnetic body, the magnetic flux φ ₁ is distributed not through the cross section of the magnetic body in a uniform distribution but through the shortest magnetic path having a small magnetic resistance. In this case, the movable yokes 13 and 13 '
The distance L ₁ between the work suction parts 13a, 13a ′ of is the thickness of the work 15
Since it is set to approximately twice or less than T ₁ , the magnetic flux φ ₁ will pass only through the work 15 side where the magnetic resistance becomes small. That is, by setting the distance L ₁ between the work adsorbing portions 13a and 13a ′ to a value close to the plate thickness of the work 15, the magnetic flux φ ₁ passing through the upper work 15 hardly enters the lower work 16, and Even if it gets in, it passes through without going deeply.

FIG. 4 schematically shows the change of the passage of the magnetic flux in the vicinity of the movable yoke when the distance between the workpiece suction portions 13a and 13a 'is changed. FIG. 5 shows the workpiece suction of the movable yoke. The characteristics showing the relationship between the interval between the parts and the suction force between the works are shown. In FIG. 4, φ'is the work suction part 13
The magnetic flux passing state is shown when the distance L ₁ between a and 13a ′ is set to the same level as in the conventional device, and φ ₁ ′ indicates the magnetic flux passing state in the present invention. As shown in FIG. 5, when the distance L ₁ between the work suction parts is set to 20 times the plate thickness T ₁ of the work 15, the strength of the magnetic field generated by the coil 14 is 10
At 00AT, the suction force between the works becomes close to 3kgf, and if the ratio L ₁ / T ₁ between the space L ₁ between the work suction parts and the plate thickness T of the work 15 is gradually reduced, the suction force between the works will increase. It can be seen that the ratio L ₁ / T ₁ between the distance L ₁ and the plate thickness T ₁ decreases sharply near 2. Under the condition that the ratio of this interval L ₁ and plate thickness T ₁ is L ₁ / T ₁ = 2, the suction force generated between the workpieces is 1.8 kgf, which is about 60% of the conventional type.
Decrease to. As described above, the distance L ₁ between the workpiece suction portions 13a and 13a ′ of the movable yokes 13 and 13 ′ is set to approximately 2 of the plate thickness T ₁ of the workpiece 15.
By setting the number to be equal to or less than twice, the suction force generated between the works can be greatly reduced, and it is possible to prevent two works 15 and 16 from being sucked at the same time.

Second Embodiment FIG. 6 shows a second embodiment of the present invention. The second embodiment is different from the first embodiment in the presence or absence of an auxiliary iron core, and the other parts are the same as those in the first embodiment. Therefore, the same parts as those in the first embodiment are designated by the same reference numerals, and the description of the corresponding parts will be made. Will be omitted and only different parts will be described. The same applies to other embodiments described later.

In FIG. 6, 24 indicates an auxiliary core. The auxiliary core 24 is made of a soft magnetic material extending in the horizontal direction. The auxiliary iron core 24 is located above the main iron core 12, and the movable yokes 13 and 13 'are located at both ends thereof. In the present embodiment, the movable yokes 13 and 13 'can slide while contacting the main iron core 12 and the auxiliary iron core 24.

In the second embodiment having such a configuration, the lifting magnet is moved by the transporting machine to a position directly above the stacked work pieces, and the movable yokes 13 and 13 'are lowered by their own weight and abut on the work piece 15. Here, when the coil 14 is excited, the magnetic flux φ ₁ and the magnetic flux φ ₂ are generated. Magnetic flux φ
₁ is a main iron core 12, a movable yoke 13, a work piece 15, a movable yoke
13 'and the main iron core 12 are passed in this order, and the work 15 is adsorbed by the contact surfaces 26, 26'. The magnetic flux φ ₂ is generated by the main iron core 12 and the movable yoke 1
3, the auxiliary iron core 24, the movable yoke 13, and the main iron core 12 are passed in this order, and a large attraction force is generated on the contact surfaces 28, 28 '. Therefore, the contact surfaces 27, 27 'of the main iron core 12 have magnetic fluxes φ ₁ , φ ₂
As a result, the combined magnetic flux of (3) will pass, and similarly a large attraction force will be generated.

Also in the case of this embodiment, the distance L ₁ between the work suction portions 13a, 13a 'of the movable yokes 13, 13' is ₁ to 2 of the plate thickness T ₁ of the work 15.
There is a double relationship, and most of the magnetic flux φ ₁ ′ is the work on the upper side.
After passing 15, the suction force generated between the workpieces is small. Also in this case, the relationship between the distance L ₁ between the work suction parts 13a and 13a 'and the suction force generated between the works is the same as that of the first embodiment as shown in FIG.

When the suction of the work 15 is confirmed, the arm of the conveyor (not shown) rises and the movable yokes 13 and 13 'are securely held by the friction due to the suction force generated on the contact surfaces 27 and 27', and the work 15 is lifted. To be At this time, the suction force between the works that simultaneously lifts the lower work 16 is extremely small.

When the lifting magnet moves, the work 15 gives a large force to the contact surfaces 26, 26 'due to the acceleration, and the movable yokes 13, 13' receive a bending moment. In this case, depending on the direction of acceleration, the ends of the movable yokes 13 and 13 'may be open or closed. In any case, this force causes the movable yokes 13 and 13 'to move to the main iron core 12
Or, trying to move away from the auxiliary iron core 24, the movable yokes 13, 1
Since 3'is securely attracted to and supported by the main iron core 12 and the auxiliary iron core 24, the movable yoke can be moved even if it receives a bending moment.
There is no concern that 13 and 13 'will separate from each core.

Third Embodiment FIG. 7 shows a third embodiment of the present invention. The present embodiment is a modification of the second embodiment and is an improvement of the structure of the work suction part. That is, as shown in FIG. 7, it is preferable that the distance L ₁ between the workpiece suction portions (magnetic poles) is as small as possible, but since the movable yokes should not be attracted and attracted by this, the workpiece suction portions 13a and 13a 'should not be attracted. Plate-like spacers 25, 25 'made of a non-magnetic material are attached to the inner surface. The spacers 25, 25 'are joined to the work suction portions 13a, 13a' by welding or brazing. The inner side surfaces of the work suction portions 13a, 13a 'to which the spacers 25, 25' are attached are formed as inclined surfaces. That is, the distance L ₁ between the work suction portions 13a and 13a ′ becomes larger as it goes upward. The reason why the inner surface is inclined (gradient) is to prevent one movable yoke from sliding on the stepped portion of the other movable yoke when the movable yoke slides up and down.

In the third embodiment configured as described above, the inner surfaces of the work suction portions 13a and 13a 'are inclined,
The average distance between the work adsorbing portions 13a, 13a '(magnetic poles) becomes long, and it is possible to reduce a part of the magnetic flux φ ₁ directly bypassing from one magnetic pole to the other magnetic pole. Can be increased. The smaller the width dimension D of the lower end surfaces of the workpiece suction portions 13a, 13a 'that come into contact with the workpiece 15 is to reduce the suction force generated between the workpieces as much as possible (the limit is D ≧ T), but too small. ,
The durability of the lower end surfaces of the movable yokes 13a and 13a 'is deteriorated. However, in this case, if the lower end surfaces of the spacers 25, 25 'are made flush with the lower end surfaces of the movable yokes 13a, 13a', the surface pressure acting on the lower end surfaces of the movable yokes 13a, 13a 'can be reduced. It is possible to prevent deterioration of durability.

Fourth Embodiment FIG. 8 shows a fourth embodiment of the present invention. This embodiment differs from the first embodiment in the shapes of the main iron core and the movable yoke. The length of the upper surface and the length of the lower surface of the main iron core 32 in the axial direction are different, and the length of the upper surface is shorter than that of the lower surface. Therefore, both end surfaces of the main iron core 32 are inclined surfaces. The movable yokes 33, 33 'have the same shape of the work suction portions 33a, 33a' at the lower end as those in the first and second embodiments, and the upper portion attracted to the main iron core 32 is the main iron core 32.
It is formed so as to be parallel to both end surfaces formed on the inclined surface. That is, the movable yokes 33, 33 'are connected to the main iron core 32.
They are arranged in a figure-of-eight shape across.

In the third embodiment constructed in this manner, since both end surfaces of the main iron core 32 to which the movable yokes 33, 33 'are attracted are formed as inclined surfaces, the weight of the work 15 is abutted on the contact surfaces 34, 34. ′
Effectively assists the attraction force by the magnetic flux φ ₁ . Therefore, even if, for example, the tips of the movable yokes 33, 33 ′ try to open (or close) due to a bending moment, the ability to suppress them is enhanced, and the movable yokes 33, 3 ′ are
The holding power of 3'can be further improved.

Fifth Embodiment FIG. 9 shows a fifth embodiment of the present invention. In the figure,
Reference numerals 42 and 42 'indicate main iron cores, and the main iron cores 42 and 42' are arranged at positions facing each other. Main iron core 42, 42
Are integrally formed via a C-shaped iron core portion 40, and the coils 14, 14 'are located on the outer circumferences of the respective main iron cores 42, 42'. Above the main cores 42, 42 ', auxiliary cores 44, 4'
4'is located. The auxiliary iron cores 44 and 44 'extend inward from the C-shaped iron core portion 40 along the main iron cores 42 and 42'.
A movable yoke 43 is located on the end faces of one of the main iron core 42 and the auxiliary iron core 44.

The movable yoke 43 is a bar-shaped member made of a soft magnetic material that extends in a straight line in the vertical direction, and has the same cross section over the entire length. The movable yoke 43 is slidable while being in contact with the main iron core 42 and the auxiliary iron core 44. A movable yoke 43 'is located on the end faces of the other main iron core 42' and the auxiliary iron core 44 '. The structure and the arrangement position of the movable yoke 43 'conform to those of the movable yoke 43 described above. The coils 14, 14 'located on the outer circumferences of the main iron cores 42, 42' are connected to a power source (not shown), and the magnetic fluxes φ ₃ , φ ₄ , generated by the coils 14, 14 ',
φ ₅ is generated in the same direction as shown in FIG.

Next, the operation will be described. This embodiment is basically the same as the second embodiment, but since the main iron cores 42, 42 'are arranged outside the movable yokes 43, 43', the work attraction members (magnetic poles) 43a, 43a '. Even though the distance L ₁ is set to be small, the movable yokes 43 and 43 ′ can be made linear. Therefore, the bending moment due to the acceleration when the work 15 is conveyed is hardly received, and it is only necessary to consider the force in the displacement direction. Further, by the action of the magnetic fluxes φ ₄ and φ ₅ passing through the auxiliary iron cores 44 and 44 ′ and the magnetic flux φ ₃ passing through the iron core portion 40, the attracting force of the contact surfaces 45 and 45 ′ is increased, and the movable yokes 43 and 43 ′. Since the holding force can be increased, the work 15 can be lifted and transported extremely stably in combination with the above action.

Also in this case, the distance between the workpiece suction portions 43a and 43a 'of the movable yokes 43 and 43' is the same as the condition of the first embodiment.
The suction force generated between the works is also extremely small.

〔The invention's effect〕

According to the movable yoke type lifting magnet according to the present invention, the distance between the workpiece attracting portions of the movable yokes facing each other is
Since the plate thickness of the workpiece to be attracted is set to approximately twice or less, almost all of the magnetic flux from one movable yoke to the other movable yoke can be passed through the workpiece only by contacting the movable yoke. Become. As a result, even when a plurality of works are stacked, the suction force generated between the works attracted to the movable yoke and the works located below the works can be significantly reduced.

Therefore, it is possible to automatically and reliably hoist a plurality of works stacked one by one, and prevent a harmful effect when, for example, two works are attracted by a press machine. As a result, it is possible to significantly reduce the occurrence of troubles on the automated sheet metal processing line.

[Brief description of drawings]

1 is a front view of a movable yoke type lifting magnet according to a first embodiment of the present invention, FIG. 2 is a side view of FIG. 1, and FIG. 3 is a magnetic flux passage in the vicinity of the movable yoke in the apparatus of FIG. FIG. 4 is a schematic diagram showing a system path, FIG. 4 is a schematic diagram showing a change state of a magnetic flux passage path when the distance between the workpiece suction portions is changed, and FIG. 5 is a distance between the workpiece suction portions of the movable yoke and the workpiece. 6 is a front view of a movable yoke type lifting magnet according to a second embodiment of the present invention, and FIG. 7 is a movable view according to a third embodiment of the present invention. 8 is a front view of a yoke type lifting magnet, FIG. 8 is a front view of a movable yoke type lifting magnet according to a fourth embodiment of the present invention, and FIG. 9 is a front view of a movable yoke type lifting magnet according to a fifth embodiment of the present invention. Figures and 10 are conventional Front view illustrating an example of a movable yoke lifting magnet, FIG. 11 is a schematic view, showing the passing path of the magnetic flux in the vicinity of the movable yoke of the apparatus of FIG. 10. 12, 32, 42, 42 '... Main iron core 13, 13', 33, 33 ', 43, 43' ... Movable yokes 13a, 13a ', 33a, 33b', 43a, 43a '... Work suction part ( Magnetic poles) 14,14 ′ …… Coil 15,16 …… Workpieces 24,44,44 ′ …… Auxiliary iron core L ₁ …… Spacing between workpiece suction parts T ₁ …… Workpiece plate thickness

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsunori Minamizawa 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Automobile Co., Ltd. (72) Inventor Hideo Niwa 6-10 Ushimaki Town, Mizuho-ku, Nagoya City, Aichi Prefecture Sanmei Within Denki Co., Ltd. (56) References Japanese Patent Publication No. Sho 57-20232 (JP, B2)

Claims (1)

(57) [Claims] 1. A movable yoke-type lifting magnet having a plurality of movable yokes which are arranged facing each other so as to be attracted to a main iron core provided with a coil on the outer periphery and are movable in the vertical direction according to the shape of a workpiece to be attracted. 2. The movable yoke type lifting magnet according to claim 1, wherein the interval between the workpiece adsorbing portions of the movable yokes facing each other is set to be approximately twice the plate thickness of the workpiece or less.