JPH0347229Y2 - - Google Patents

Description

[Detailed Description of the Invention] <<Industrial Application Field>> This invention relates to a limit switch used as an object detection switch in, for example, a conveyor line.

《Summary of the idea》 When a limit switch is used near a welding machine, spatter from the welding machine can adhere to the switch's moving parts, mounting parts, display parts, etc., causing malfunctions or unclear display contents. I become familiar with it.
As one measure to prevent this, we placed a nameplate on the transparent back of the cover that covers the switch case body to prevent spatter from adhering to the nameplate.

<<Prior Art>> FIG. 10 shows an example of a conventional limit switch. A basic switch 2 is built into the case body 1, and a cover 3 is attached to the top of it.
covered by. Operator 2a of switch 2
is operated by the plunger 4, and the plunger 4
is operated by a rotating shaft 6 within a head 5 attached to the case body 1. The rotating shaft 6 has a flat portion 6a inside the head 5, and a plunger 8, which is biased by a compression coil spring 7, is in pressure contact with this portion 6a under normal conditions.
is held in a neutral position. The base end of the operating lever 9 is attached to the tip of the rotating shaft 6 with a hexagon socket head bolt 10.
The tip of the operating lever 9 has a
A roller 12 is rotatably attached via a roller shaft 11. Note that a nameplate 13 is attached to the cover 3.

This limit switch is placed, for example, on a conveyor line, and when a dog on the conveyor hits the roller 12 and rotates the lever 9, the flat portion 6a of the rotating shaft 6 rotates and presses the plunger 4.
As a result, the actuator 2a of the basic switch 2 is actuated to operate the basic switch 2. This switch 2
The operation is taken out to the outside through the terminal screws 2b and 2c. When the dog passes, lever 9
Since the rotation shaft 6 returns to its original neutral position by the compression coil spring 7 in the head 5, it similarly returns to the neutral position, and the plunger 4 also stops pressing against the actuator 2a.

<<Problems to be solved by the invention>> Such a limit switch has a robust structure and reliable operation under normal use environments. However, when used near arc welding machines, spot welding machines, etc., hot molten material called spatter that scatters from the welding machine adheres to the case body, etc., and this gradually accumulates and grows, causing malfunction. . In particular, adhesion to actuator parts such as operating levers causes premature malfunction. Also,
If spatter sticks to the nameplate, it becomes impossible to check the contents of the nameplate. If the limit switch has a window on the nameplate and you can check whether the operation indicator lamp is lit through the window, you will not be able to confirm whether the lamp is lit or not.

Therefore, the purpose of this invention is to prevent the adhesion and accumulation of spatter on the cover that covers the case body that houses the basic switch, and to prevent the adhesion and accumulation of spatter on the basic switch that is attached to the inside of the case body from the outside by passing through the cover. To provide a limit switch which is improved so that the operating state of the switch can be constantly monitored and the material of the cover can be selected from a material effective for preventing spatter.

<Means for Solving the Problems> The limit switch according to this invention includes a basic switch housed in a case body, a cover that covers the case body, and an actuator attached to the case body to operate the basic switch. In the limit switch, the cover has a transparent or semi-transparent part having a convex curved surface or a convex spherical surface, and is integrally formed with the transparent or semi-transparent part by outsert molding, and is attached to the case body. a rubber lamp hold cover equipped with a name plate, an operation indicator light, a contact spring, etc., is inserted and fitted in this order into a recess on the back side of the transparent or translucent part of the cover; The contact spring is characterized in that it is brought into contact with a normally open terminal of a basic switch.

<<Example>> FIG. 1 and FIG. 2 show an example of this invention. The reference numerals used in the description of the conventional example in FIG. 10 are used for similar members.
Inside the case body 1 formed in a rectangular box shape, there are 2
A circuit double-break basic switch 2 is screwed through an insulating cloth. The opening of the case body 1 is covered with a cover 3 via a gasket 14, and the cover 3 is fixed to the case body 1 with screws 15.

The cover 3 includes a transparent resin portion (including semi-transparent) 16
The nameplate 13 is inserted into the recess on the back side of the transparent resin part 16, and serves as an operation indicator lamp.
Neon lamp 19, resistor 20 and contact spring 21
A lamp hold cover 22 made of rubber is fitted. A transparent (including translucent) lamp display board 23 is inserted into the upper surface of the neon lamp 19. The contact spring 21 connects the cover 3 to the case body 1.
Normally open terminal 2 of basic switch 2 when attached to
contact b. Terminals of lead wires introduced into the conduit port 24 of the case body 1 via connectors are connected to two normally open terminals 2b and two normally closed terminals 2c of the basic switch 2, respectively.

The tip 25a of the auxiliary plunger 25 is in contact with the actuator 2a of the basic switch 2, and the auxiliary plunger 25 is protected within the actuation plunger 4 which is slidably attached to the case body 1 via a bearing 26. It is slidably inserted via a compression spring 27 for use. The auxiliary plunger 25 is prevented from coming off by a stop ring 28 fitted into the inlet of the operating plunger 4. A seal cap 29 made of rubber is fitted into the tip of the operating plunger 4, and a stopper 30 is press-fitted therein.

A head 5 is attached to the case body 1 by four screws 31 in relation to the tip of the actuating plunger 4. A return plunger 8 is slidably inserted into the head 5 coaxially with the operating plunger 4 via a compression coil spring 7 for return. A rotary shaft 6 is also mounted in the head 5 in a direction perpendicular to the return plunger 8 via a bearing 32. Both surfaces of the rotating shaft 6 facing the return plunger 8 and the actuating plunger 4 are cut off to form a flat cam portion 6a. The pads 30 at the tips of the return plunger 8 and the operating plunger 4 are pressed against both surfaces of the cam portion 6a by the pressing force of the springs 7 and 27, respectively, and hold the rotating shaft 6 in a neutral position.

The rotating shaft 6 protrudes from the boss portion 5a of the head 5, and an O-ring 33 is interposed between the rotating shaft 6 and the bearing 32. The tip of the boss portion 5a is covered with a bottomed cylindrical resin cap 34 having a hole through which the rotating shaft 6 passes. A mounting hole 9a at the base end of the operating lever 9 is fitted into a portion of the rotating shaft 6 that protrudes from the resin cap 34. This mounting hole 9
a has a slot 9b extending in the longitudinal direction through its center, and by tightening this slot 9b with a hexagon socket head bolt 10 perpendicular to this slot, the operating lever 9 is fixed to the rotating shaft 6. . A roller 12 is attached to the tip of the operating lever 9 by caulking the tip 11a of the roller shaft 11.
Rotatably mounted.

Each of these parts from the head 5 to the roller 12 constitutes the actuator of this limit switch. The four screws 31 for attaching the head 5 to the case body 1 are arranged in the same direction and at equal distances from the axis of the actuating plunger 4, so the head 5 is attached to the case body 1 at 90 degree intervals. It can be mounted in either direction.

Next, the operation of the limit switch will be explained. When the roller 12 at the tip of the lever 9 hits a dog or the like and the lever 9 rotates, the rotating shaft 6 fixed to the lever 9 also rotates. Since a flat plate-shaped cam portion 6a is formed at the lower part of the rotating shaft 6, the rotating shaft 6
The rotation of the cam portion 6a causes the cam portion 6a to press the stopper 30 at the tip of the operating plunger 4. Actuation plunger 4
This movement is transmitted to the auxiliary plunger 25 via the spring 27, and its tip 25a presses the actuator 2a of the basic switch 2 to turn on the basic switch 2. When the auxiliary plunger 25 advances a certain amount and the actuator 2a reaches its limit of movement, further rotation of the lever 9 is absorbed by the actuating plunger 4 moving forward while compressing the spring 27 inside.

When the roller 12 at the tip of the lever comes off the dog, the lever 9 returns to its original neutral position by the restoring force of the return spring 7 pressing the cam portion 6a of the rotating shaft 6 via the return plunger 8. As a result, the lever 9 also returns to its original neutral position. Then, the operating plunger 4 is returned to its original state by the restoring force of the spring 27 therein, and the operation of the basic switch 2 is turned off.

Two windows 13a and 13b of the same shape are formed on the nameplate 13, and lighting of the neon lamp 19 can be confirmed through either one of the windows. neon lamp 19
is attached to the lamp hold cover 22 that is fitted on the back side of the cover 3, and the neon lamp 1
When the lamp holder cover 22 is fitted to the back side of the cover 3 so that 9 is visible from the name plate 13b as shown in the figure, the contact spring 21 is connected to the normally open terminal 2b of the basic switch 42, and the neon lamp 19 is connected to the basic switch 42. Lights up only when switch 2 is off, indicating when the switch is inactive. On the other hand, neon lamp 1
When the lamp hold cover 22 is attached so that the contact spring 9 is seen through the other window 13a, the contact spring 2
1 is connected to the normally closed terminal 2c of the basic switch 2,
The neon lamp 19 lights up only when the basic switch 2 is on, to indicate when the switch is in operation. A "notification mark" or lamp display board 23 provided on the front surface of the neon lamp 19 indicates when the limit switch is in operation.

The case body 1 and the head 5 are made of aluminum die-cast alloy, and the lever 9 is made of aluminum cast alloy. And to prevent spatter adhesion,
Each surface is coated with melamine. This coating has good heat resistance and good release properties against sputtering, such as tetrafluoroethylene, fluorine, etc.
This can be accomplished by painting with a resin such as silicone, silicon fluoride, or glass resin, or with a rubber material or ceramic material, or by depositing with a metal material such as nickel or chromium. Good mold releasability also requires that the surface be smooth.

Alternatively, the parts themselves such as the case body 1, head 5, lever 9, etc. can be made of these materials with good heat resistance and mold releasability. These materials include stainless steel, and in the above embodiment, roller shaft 11 and roller 1
2. The hexagon socket head bolt 10, mounting screw 31, etc. are made of stainless steel.

The entire limit switch including the case body 1, cover 3, etc. may be coated or formed with these materials, but at least the movable part and the support part, in the above embodiment, the lever 9 and the head 5, and the roller 12 and the lever. It should be done for 9.

A resin cap 34 is provided between the lever 9 and the head 5 for the same purpose. Although tetrafluoroethylene is used in this example, other resin materials having good heat resistance and mold release properties can be used as well. Further, as shown in FIG. 3, the resin cap 34 may cover the entire boss portion 5a together with the rotary shaft 6. In the case of a resin cap, since it has flexibility, it has better installation workability and sealing performance than other materials.

Furthermore, as shown in FIG. 4, the head of the hexagon socket head bolt 10 for attaching the lever 9 to the rotating shaft 6 may be covered with a cap 35 molded from a similar resin or rubber material. This cap 35
As shown in Fig. 5, a large number of pieces made of silicone rubber are cut out one by one and used. This cap 35 may be used to cover the entire head of the hexagon socket head bolt 10 as shown in FIG. 6, or to cover the head of other screws or to close the mounting hole after the screw is installed. You can.

Further, as shown in FIG. 7, the lever 9 and the boss portion 5a of the head 5, which is its supporting portion, may be covered with a cover 36 made of a similar resin, rubber, or metal material. This cover 36 is attached to the lever 9
The head 5 and the case body 1 may be entirely covered. In this case, the lever 9 is
The cover needs to be formed with a sufficient size, or the portion between the lever 9 and the case body 1 needs to be flexible so that it can move relative to the case body 1.

In this embodiment, in addition to the measures to prevent spatter adhesion using coatings, covers, and materials of the parts themselves, measures to prevent spatter adhesion are provided based on the shape of the parts themselves. That is, as is clear from FIG. 1, the surface of the cover 3 that covers the case body 1 is formed into a convex curved surface. This convex curved surface may be a cylindrical surface having a curvature in the vertical direction of the cover 3 as shown in the figure, a cylindrical surface having a curvature in the horizontal direction, or another convex curved surface. Further, it may be an elliptical spherical surface, a perfect spherical surface, another convex spherical surface, or a combination thereof. in this way,
By making the surface of the cover 3 a convex curved surface or a convex spherical surface, spatters flying from the welding machine hit this surface and scatter, making it difficult for them to adhere to the cover surface. Further, in the case of transparent resin, there is a lens effect, and the display contents on the nameplate 13 under the transparent resin part 16 can be easily seen.

A convex curved surface or a convex spherical surface is, as shown in Fig. 8,
They may be provided only in the portions of the nameplate 13 of the cover 3 corresponding to the windows 13a and 13b. In the case of a limit switch with an operation indicator lamp, it is important to check the operation by lighting the lamp, so at least make sure that spatter does not adhere to the parts corresponding to the windows 13a and 13b where it is confirmed that the lamp is lit, and to prevent the lens effect. This allows the light from the lamp to be diffused.

Also, if the operation indicator lamp is not included, cover 3
The entire structure may be made of opaque resin or metal material such as aluminum die-casting. In addition, as another embodiment, the surface of the cover 3 can be made flat, so that the surface or the above-mentioned convex curved or convex spherical surface, especially the resin surface, can be made of highly heat-resistant glass resin, ceramic, or tetrafluoride. Coating with materials such as ethylene, fluorine, silicone, and silicon fluoride is preferred from the viewpoint of improving heat resistance.
If the device is equipped with an operation indicator lamp, the coating material must be transparent (including translucent). Further, instead of coating, a sheet made of the above material may be attached.

<<Effects of the invention>> As described above, the limit switch according to this invention includes a basic switch housed in a case body, a cover that covers the case body, and an actuator that is attached to the case body and operates the basic switch. In the limit switch, the cover has a transparent or semi-transparent part having a convex curved surface or a convex spherical surface, and is integrally formed with the transparent or semi-transparent part by outsert molding, and is attached to the case body. A rubber lamp hold cover equipped with a name plate, an operation indicator light, and a contact spring is inserted and fitted in this order into the recess on the back side of the transparent or translucent part of the cover, and Since the contact spring is brought into contact with the normally open terminal of the basic switch, spatter from the welding machine will not be deposited on the cover surface and the basic switch will not malfunction. There isn't. Also, the fact that spatter can be prevented from accumulating on this cover means that the operating status of the basic switch can be constantly monitored by lighting a neon lamp installed inside from the outside through this cover. It is effective in ensuring that no information becomes unclear. In addition, as a result of the cover having a convex curved surface or a convex spherical surface, the cover itself exhibits a lens effect, and this lens effect makes it possible to more reliably monitor the lighting of the neon lamp, etc.
By using resin for the cover, various materials can be selected as measures against spatter, and as a result, measures against spatter can be taken more effectively.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a limit switch showing one embodiment of this invention, Fig. 2 is a front view of the limit switch shown in Fig. 1, and Fig. 3 shows another embodiment of the resin cap in this invention. 4 is a cross-sectional view, and FIG.
The figure is a perspective view of the hexagon socket head bolt cap, No. 6.
The figure is a perspective view showing another embodiment of the cap for hexagon socket head bolts, FIG. 7 is a perspective view showing an example of the spatter adhesion prevention cover in this invention, and FIG. 8 is a perspective view showing the case cover in this invention. FIG. 9, a perspective view showing another embodiment, is a partially sectional perspective view showing an example of a conventional limit switch. 1...Case body, 2...Basic switch, 2b
... Normally open terminal, 3 ... Case cover, 4 ... Operating plunger, 5 ... Head, 6 ... Rotating shaft, 7 ...
... Return spring, 8 ... Return plunger, 9 ... Operating lever, 10 ... Hexagon socket head bolt, 11 ... Roller shaft, 12 ... Roller, 13 ... Nameplate, 1
5... Screw, 16... Transparent resin part (semi-transparent resin part), 17... Aluminum die-casting part, 19... Neon lamp (operation indicator lamp), 20... Resistor,
21...Contact spring, 22...Rubber lamp hold cover.

Claims (1)

[Scope of utility model registration request] A limit switch comprising a basic switch housed in a case body, a cover that covers the case body, and an actuator that is attached to the case body and operates the basic switch, the cover having a convex curved surface on its surface. or a transparent or semi-transparent part having a convex spherical surface, and an aluminum die-cast part integrally formed with the transparent or semi-transparent part by outsert molding and attached to the case body, and the transparent or semi-transparent part of the cover Insert and fit the rubber lamp hold cover equipped with a name plate, operation indicator light, contact spring, etc. into the recess on the back side of the translucent part in this order, and make sure that the contact spring is in contact with the normally open terminal of the basic switch. Features a limit switch.