JPH0738506B2 - Molding frame having tapped pilot hole and molding die therefor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a molding frame having a surface inclined with respect to a mold opening / closing direction and having a tapping screw pilot hole formed therethrough, and a molding mold therefor. .

(Prior Art) Conventionally, a frame formed of plastic or the like has a surface inclined with respect to the opening / closing direction of a molding die (hereinafter referred to as a die), and when a printed circuit board or the like is attached to the surface, a prepared hole is formed. It is general that the boss to be formed is integrally formed on the inclined surface, a printed circuit board having a mounting hole is mounted on the boss, and the boss is fixed while raising a screw with a mounting screw.

FIG. 5 is a sectional view of a molding frame and a printed circuit board according to a conventional technique. Molding frame (hereinafter referred to as frame)
1 is integrally molded of plastic or the like, and is a frame mounting surface 1a perpendicular to the direction of the arrow AB which is the opening and closing direction of the mold and a printed circuit board mounting surface 1b inclined to the frame mounting surface 1a (hereinafter mounting surface). 1b)). The mounting surface 1b is provided with a boss 2 and vertical pressing pieces 3 and 4 which also serve as abutting members. A prepared hole for a tapping screw penetrates through the boss 2.

Next, the operation of mounting the printed circuit board 5 on the frame 1 will be described. The printed board 5 is placed on the boss 2 and the piece 4, and the end 5b of the printed board 5 is brought into contact with the piece 3.
Since the mounting hole 5a of the printed circuit board 5 is positioned above the pilot hole of the boss 2, the tapping screw 6 is inserted into the pilot hole through the mounting hole 5a.
The printed circuit board 5 is fixed to the boss 2 while raising screws.

Next, the molding die of the frame 1 will be described with reference to FIG.

FIG. 6 is a mold cross-sectional view of a conventional molding frame. The mold is composed of a fixed side mold (hereinafter referred to as the fixed side) 7 and a movable side mold (hereinafter referred to as the movable side) 8 and can be opened and closed by a parting line (hereinafter referred to as PL) 11 which is a mold dividing surface. . Between the fixed side 7 and the movable side 8, there is a space having substantially the same size and shape as the frame 1, that is, a cavity portion 10. The movable side 8 has a slide core (not shown) that slides in the direction of arrow C when the movable side 8 moves in the direction of arrow A, and the core 9 is planted in the slide core. The core 9 forms the prepared hole of the tapping screw 6 shown in FIG.

Next, the operation of molding the frame 1 with this mold will be described. After fixing the die to the injection molding machine (not shown), press the start button (not shown). The movable side 8 is pressed against the fixed side 7 with a predetermined mold clamping pressure. Next, the melted resin is filled in the cavity 10 by applying pressure. Then, the movable side 8 is opened in the direction of arrow A when cooled in the mold for a predetermined time and solidified. At this time, the core 9 moves in the direction of arrow C in accordance with the movement of the movable side 8. Frame 1 is movable side 8
It moves in the direction of arrow A while it is difficult to move, and a short time before the movable side 8 stops, the eject pin (not shown) in the movable side 8 moves relatively in the direction opposite to the direction of arrow A, and the molded product moves. Projected from side 8.

(Problems to be Solved by the Invention) By the way, as long as a stationary body such as a printed circuit board is attached, it is sufficient that the thread of the tapping screw, the prepared hole of the frame and the contact portion are half. However,
In the conventional frame, since the tapping screw pilot hole is circular, the printed circuit board is attached while making a screw thread all around the pilot hole. Therefore, a strong tightening force is required, the number of products is increased, and when the number of times of screw tightening is increased, a lot of labor is required for the worker.

Further, if the holes are inclined with respect to the opening and closing direction of the mold, an undercut may occur in which the core is caught by the molded product when the mold is opened. Therefore, in the conventional molding die, the core that forms the prepared hole has a slide core structure that moves in a direction different from the opening / closing direction of the die. By the way, when the mold has a slide core structure, the structure of the mold becomes complicated, and the parts constituting the slide core are greatly worn, which causes a failure. Further, there is a problem that it takes time to design and manufacture a mold and a molding cycle, which hinders a production plan.

The present invention provides a forming frame having a prepared hole that can easily tighten a tapping screw, and even if the prepared hole is inclined with respect to the mold opening direction, the forming frame can be formed without using a slide core structure. An object is to provide a mold that can be molded.

(Means for Solving the Problems) In order to achieve the above object, in the molding frame of the present invention, the shape of the prepared hole is a semicircle having the prepared hole effective diameter, and the side where the prepared hole effective diameter exists is substantially in the center. The inner diameter was used as a boundary and the opposite side was used.

Further, when the prepared hole is inclined with respect to the opening / closing direction of the mold, the split surface of the core for molding the prepared hole is provided at the center inner diameter of the prepared hole and is undercut to the prepared hole. Align the side dividing surface with the opening and closing direction of the mold.

(Operation) When a printed circuit board or the like is mounted on the molding frame having the prepared hole as described above, the mounting hole of the printed circuit board is used as a guide and the tapping screw is used to tighten the screw while tightening the screw. Since the effective diameter of the prepared hole is only a semicircle from the inner diameter of the central part, the resistance to tapping is halved.

Further, according to the molding die of the molding frame configured as described above, when the molten resin is filled in the cavity portion of the die, cooled and solidified, and then the die is opened, the prepared hole is formed. Since the PL of the core has no undercut portion with respect to the molding frame, it can be divided in the opening and closing direction of the mold at approximately the center of the prepared hole.

Therefore, the tapping screw can be easily tightened, and even if the prepared hole is inclined with respect to the mold opening / closing direction, the molding frame can be molded without using the slide core structure.

(Example) An example of the present invention will be described with reference to the drawings. The elements common to the drawings are given the same reference numerals.

FIG. 1 is a sectional view of a molding frame and a substrate of the present invention, and FIG. 2 is a sectional view taken along the line EE of FIG. The only difference from the prior art is the shape of the pilot hole for the tapping screw. The component mounting surface 22a of the frame 22 is integrally formed with a boss 22b and vertical pressing pieces 22c and 22d which also serve as an abutment. The boss 22b is provided with a through hole for a tapping screw. As shown in FIG. 2, the shape of the prepared hole is a half circumference of the prepared hole effective portion, and the upper part is on the right side and the lower part is on the left side with the side where the prepared hole effective part is located as the boundary of the inner diameter of the central part. . Therefore, the escape 22e exists on the upper left side and the escape 22f exists on the lower right side.

Next, the operation of mounting the printed circuit board 5 on the frame 22 will be described. The printed circuit board 5 is placed on the boss 22b and the piece 22c, shifted in the direction of arrow F, and the end 5b is abutted against the piece 22d. At this time, the mounting hole 5a of the printed board 5 is located above the tapping screw pilot hole formed in the boss 22b. In this state, the tapping screw 6 is screwed in while using the mounting hole 5a of the printed board 5 as a guide. The tapping screw 6 is advanced by making a half turn on each of the upper and lower portions of the prepared hole of the frame 22.
When the printed circuit board 5 is attached to the frame 22, a couple force acting in the direction of the arrow G is generated in the printed circuit board 5 because the screw effective portions are on the opposite sides of the upper portion and the lower portion. However, the end portion 5b of the printed circuit board 5 cannot be rotated because it is restricted in vertical movement by the pieces 22c and 22d, and is fixed to the frame 22.

Next, a molding die for the frame 22 will be described.

FIG. 3 is a mold cross-sectional view of a molding frame according to the present invention, and FIG. 4 is a DD cross-sectional view in which the fixed side of FIG. 3 is enlarged. The fixed side 12 and the movable side 13 can be divided by PL14, and the movable side 13 can be opened and closed with respect to the fixed side 12 in the direction of arrow AB. Hereinafter, the description will be focused on the core for forming the prepared hole.
The core forming the pilot hole can be divided into a fixed side 12 and a movable side 13 at an inner diameter 16 of the central portion of the pilot hole. PL on the right side 17 of the fixed side 12
Is a right angle to the surface 19 inclined in the direction of arrow AB, and the left side surface
The PL of 18 coincides with the arrow AB direction. On the other hand, the movable side
The PL of the right side surface 21 of 13 coincides with the arrow AB direction, and the PL of the left side surface is at right angles to the inclined surface 19. Therefore, the DD sectional view is oval as shown in FIG. Therefore,
The core for forming the prepared hole does not have a portion that undercuts the molded product when the mold is opened in the direction of arrow A. The cavity portion 15 is a space for molding the frame.

Next, the operation of molding the frame with this mold will be described only with respect to differences from the prior art.

The plastic resin filled in the cavity 15 cools, shrinks as it solidifies, and is hard to adhere to the fixed side 12 and the movable side 13. When the plastic resin is solidified, the movable side 13 is opened in the direction of arrow A. Since the molded frame has a larger area where the movable side 13 is harder than the fixed side 12, it is moved in the direction of arrow A together with the movable side 13. The following is similar to the conventional technique.

Although the prepared hole has an oval shape in this embodiment, it may have a front-rear circular shape.

(Effects of the Invention) Since the present invention is configured as described above, it has the effects described below.

By making the effective diameter of the prepared hole a half circle, the tightening force of the tapping screw is halved. Therefore, the worker can easily perform the screw tightening action even if the number of tightening points increases.

Also, if the prepared hole is inclined with respect to the mold opening and closing direction, if the effective diameter of the prepared hole is a semi-circle, the core formed by the prepared hole can have a simple structure corresponding to the opening and closing direction of the mold, The core does not have to have a complicated slide core structure. Therefore, the number of mold failures is reduced and the production plan is not hindered. or,
We can deal with mold design and production in a short time.

[Brief description of drawings]

FIG. 1 is a sectional view of a molding frame and a substrate of the present invention, and FIG.
1 is a sectional view taken along the line EE of FIG. 1, FIG. 3 is a sectional view of the mold of the molding frame according to the present invention, FIG. 4 is a sectional view taken along the line D-D of FIG. 3, and FIG. FIG. 6 is a cross-sectional view of a molding frame and a substrate according to the technique, and FIG. 6 is a mold cross-sectional view of the molding frame according to the conventional technique. 1,22 …… Frame, 5 …… Printed circuit board, 6 …… Tapping screw, 7,12 …… Fixed side, 8,13 …… Movable side, 9 …… Core, 10,15 …… Cavity part.

Claims (2)

[Claims] 1. A molding frame in which a boss having a pilot hole is provided on a mounting surface, and a printed circuit board or the like is mounted on the boss while tapping the pilot hole with a tapping screw. The shape of the pilot hole has an effective diameter of the pilot hole. A molding frame, characterized in that it is a semicircle, and the sides on which the effective diameter exists are opposite sides with the inner diameter of the central portion as a boundary. 2. A tapping screw pilot hole penetrating at right angles to a surface inclined with respect to the opening / closing direction of the mold, the pilot hole having an effective diameter of a semicircle, and the side on which the effective diameter exists is In a molding die that molds on the opposite side with the inner diameter of the center of the prepared hole as a boundary, the split surface of the core that forms the prepared hole is provided at the inner diameter of the center and undercut to the prepared hole. A molding die, characterized in that the dividing surface on the side of is aligned with the opening and closing direction.