JPH0256766B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for molding a photoelectric switch, and more specifically, the present invention relates to a method for molding a photoelectric switch, and more specifically, the present invention relates to a method for molding a photoelectric switch. Concerning a molding method that can protect against damage.

(Prior Art) Conventionally, the following two methods have been generally used for molding photoelectric switches.

The first method is to house and secure components such as a light emitting element, a light receiving element, and a board on which electronic circuit components are placed in one of the two housings of the photoelectric switch. After that, connect the power cord, output cord, etc. connected to the light emitting element, etc.
After the cord is inserted into a hole for the pull-out cord drilled in the housing and pulled out to the outside, the other housing is joined to this housing. This is a method of forming the bonded portion by bonding the bonded portion using an adhesive or ultrasonic fusion.

The second method is to pour resin melted at a low temperature (for example, about 60 degrees) into the gap in the housing housing the electronic circuit components (for example, see Utility Model Application No. 57-143642, (See No. 141540, 1983).

(Problems to be Solved by the Invention) However, these methods have the following problems.

The first method requires a lot of man-hours because it is necessary to join the two halves of the casing using adhesive or ultrasonic welding, and there are also problems with waterproofing and dustproofing. . In order to solve this problem, it is necessary to fit packing, O-rings, etc. into the joints of the casing and through-holes for pulling out power cords, etc., which requires complexity and the number of parts used. The number will increase.

On the other hand, in the second method, the melt is kept at normal pressure (1 atm).
Since the liquid is poured into the container in a dry state, there are gaps and air bubbles accumulate inside the casing, which causes problems with its waterproof and dustproof properties.

(Means for Solving the Problems) The present invention is a method for molding a part of the housing of a photoelectric switch. and/or holding and fixing the light receiving element,
A front side of the substrate is surrounded by a heat resistant member to form a sealed first space around the electronic circuit member, and a back side of the substrate is surrounded by the heat resistant member and a partially open housing. A photoelectric switch which surrounds a part of the housing to form a sealed second space, and pressure molds a part of the housing with resin melted at high temperature so that the influence of molding pressure is not applied to the first and second spaces. This is a molding method.

(Function) When the present invention is used, since the electronic circuit members and the board are completely isolated from the melted high-temperature resin by the first and second spaces, these members, etc. are not affected by the high heat and pressure during molding. It becomes possible to produce a photoelectric switch that is not damaged and has excellent waterproof and dustproof properties.

(Example) Next, the present invention will be described in detail based on an example.

Figure 1 shows the photoelectric switch operating section (see Figure 2).
The housing 1 of the photoelectric switch has an opening 2 for accommodating the photoelectric switch operation part 14 on the top and rear side of the housing 1, and a lens 3 is integrally formed on the front side of the housing 1. .

Figure 2 shows the photoelectric switch operating section.
The heat-resistant bent body 4 has a heat-resistant holding portion 10.
By connecting with
and a substrate 1 on which an electronic circuit section 12 connected to a sensitivity adjustment resistor 6 is mounted via lead wires 13.
It is formed so as to sandwich 1.

That is, one end 4a of the bent body 4 is bent outward at a right angle, and an operation indicator lamp 5 and a variable resistor for sensitivity adjustment are connected to the electronic circuit section 12 between the one end 4a and the bent part 4b. A protruding portion 4c is vertically provided in which the holder 6 can be housed. A cable 7 connected to a power source and a signal processing section is inserted into the opening 4e between the bent portion 4b and the other end 4d. One end portion 4a of the folded body 4 is connected to the upper end portion of the holding portion 10 on which the light emitting element 8 and the light receiving element 9 are attached, and also to the upper end portion of the folded body 4.
The other end portion 4d includes the lower end portion of the holding portion 10 and the substrate 11.
It is tightly joined to sandwich the parts.

In this way, the bending body 4, the holding part 10, the board 11, and the cable 7 constitute the outer shape of the photoelectric switch operating part 14, and the outer shape of the photoelectric switch operating part 14 is configured by these parts, and the outer shape of the photoelectric switch operating part 14 is made up of the bending body 4, the holding part 10, the substrate 11, and the cable 7. , a light emitting element 8, a light receiving element 9, a cable 7, an operation indicator light 5, a sensitivity adjustment resistor 6, and an electronic circuit section 12, thereby forming a photoelectric switch operating section 14.

Then, as shown in FIG. 3, the photoelectric switch operating section 14 is housed through the opening 2 of the housing 1 so that the inner surface of the housing and the one end 4a and the other end 4d of the bending body 4 are tightly connected. . Thereby, a space (second space) is formed on the back surface side of the substrate 11 by the housing 1, the holding portion 10, and the other end portion 4d.

Thereafter, the housing 1 (the third
(see figure) is placed, a resin in a molten state at a high temperature (for example, about 300 degrees Celsius) is injected into the cavity 16 at high pressure (for example, 1 ton) using an injection molding machine.

When the resin hardens, a cable stopper bush 17a is formed, and the resin 1 as shown in FIG.
7. The photoelectric switch main body is formed by the protruding portion 4c of the photoelectric switch operation section 14, the housing 1, and the cable stopper bush 17a.

In the embodiments described above, it is also possible to form the housing and the heat-resistant member from metal.

(Effects of the Invention) As is clear from the above description, the present invention has the advantage that even if resin molten at high temperature is injected under high pressure, the electronic circuit section is not affected by the heat and pressure.
The photoelectric switch can be easily and integrally molded without causing any rocking of the photoelectric switch operating portion due to the injection pressure of the molten material. Therefore, a photoelectric switch that does not generate gaps or bubbles and has excellent waterproof and dustproof properties can be obtained.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of the housing, Figure 2 is a vertical cross-sectional view of the photoelectric switch operating part, Figure 3 is a vertical cross-sectional view of the photoelectric switch operating part housed in the housing, and Figure 4 is a vertical cross-sectional view of the mold. The plan view and FIG. 5 are longitudinal cross-sectional views of the photoelectric switch after molding. 1...Housing, 2...Aperture, 3...Lens, 4...
...Bending body, 5...Operation indicator, 6...Variable resistor for sensitivity adjustment, 7...Cable, 8...Light emitter,
9... Light receiving element, 10... Holding section, 11... Board, 12... Electronic circuit section, 13... Lead wire, 1
4...Photoelectric switch operating part, 15...Mold, 16
...Cavity, 17...Resin.

Claims (1)

[Scope of Claims] 1. A method for molding a part of a photoelectric switch housing, which comprises holding a light emitting and/or light receiving element connected by wiring to a board on which an electronic circuit member is placed at a position away from the board. At the same time, the front side of the board is surrounded by a heat resistant member to form a sealed first space around the electronic circuit member, and the back side of the board is surrounded by the heat resistant member and a partially opened space. A sealed second space is formed by surrounding it with a shaped casing, and a part of the casing is pressure molded with a resin melted at high temperature so that the influence of molding pressure is not applied in these first and second spaces. A method for molding a photoelectric switch characterized by: