JP2619715B2 - Molding method of cylindrical resin product and male mold for molding the same - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for molding a cylindrical resin product and a male mold for molding the resin product. The present invention relates to a novel molding method and a male mold for molding when molding a resin product.

(Related Art) An electromagnetic reciprocating compressor used as an air compression pump or the like includes a cylinder as described in, for example, Japanese Utility Model Laid-Open No. 57-103385.

FIG. 13 is a longitudinal sectional view of this electromagnetic reciprocating compressor. The piston main body 1 has a front piston 1A at the front and a rear piston 1B at the rear. An armature 4 is arranged between the pistons 1A and 1B. The piston body 1 is arranged on the same axis so that the pistons 1A and 1B slide in the front cylinder 2 and the rear cylinder 11, respectively. In this type of electromagnetic reciprocating compressor, the rear cylinder 11 is molded by aluminum die casting, and its sliding surface has
A metal sliding bearing 12 is arranged.

A ball 13 is arranged at the bottom of the rear cylinder 11,
The coil spring 5 is disposed between the ball 13 and the rear piston 1B via a washer 14. By interposing the ball 13 and the washer 14 between the coil spring 5 and the rear cylinder 11, the coil spring 5 can be concentric with the rear piston 1B and the rear cylinder 11.

A fixed iron core 6 around which an induction coil 7 is wound is disposed outside the piston body 1. By applying a half-wave alternating current, a pulse current or the like to the induction coil 7, the armature 4 is attracted in the direction of the fixed iron core 6 against the elastic force of the coil spring 5, and the piston body 1 vibrates. Due to this vibration, the suction hole 1C and the suction valve 1D
, Air is sucked into the compression chamber 1E, and is discharged outside through a discharge hole and a discharge valve (not shown) and the discharge port 10.

In FIG. 13, reference numeral 11A denotes the rear cylinder 11
A reference numeral 15 denotes a male screw for fixing the rear cylinder 11 to the casing 8, and a reference numeral 9 denotes a rear cover for holding the fixed iron core 6 between the casing 8 and the flange. It is.

As one method of increasing the manufacturing cost of such an electromagnetic reciprocating compressor, it is conceivable to mold the rear cylinder 11 conventionally formed by aluminum die-casting with resin.

Here, as described above, the slide bearing 12 is fixedly disposed in the rear cylinder 11, but the piston body 1 repeats reciprocating motion while rotating in the front cylinder 2 and the rear cylinder 11. Therefore, the cross-sectional shape of each of the cylinders 2 and 11 must be maintained in a perfect circle.

Thus, when the cylinders 2 and 11 are injection-molded with resin, for example, as shown in FIG. 14, of the mold composed of the movable male mold 21 and the fixed female mold 22 In the female mold 22, a metal sliding bearing 12 is fixed in advance in order to improve the roundness accuracy, while the male mold 21 has a projection 21A for inserting the bearing 12 and a thirteenth. A projection 21B for forming a hole for inserting the male screw 15 shown in the figure is formed, and after the slide bearing 12 is inserted into the projection 21A, the male mold 21 is inserted into the female mold 22. To perform resin injection from the injection port 220 of the female mold.After the injection molding, the mold 21 and the mold 22 are separated, and the extruding tool 23 is pushed to push the push pin 23A toward the protrusion 21A. By doing so, the molded product was taken out, and a resin rear cylinder in which the sliding bearing 12 was integrated was molded.

(Problems to be Solved by the Invention) In the conventional method of molding a cylindrical resin product as described above, the sliding bearing 12 is inserted into the projection 21A, and after molding the resin, the molded product is taken out of the mold 21. For this reason, the outer diameter of the projection 21A is set to be slightly smaller than the inner diameter of the slide bearing 12, and a clearance is provided between the projection 21A and the slide bearing 12.

However, when the molded resin shrinks when the resin is cured, due to this clearance, uneven stress acts on the outer peripheral surface of the sliding bearing 12, and the inner surface of the sliding bearing 12 is deformed to reduce the roundness. And the center line between the molded rear cylinder and the slide bearing 12 does not coincide with each other due to the clearance. That is, there has been a problem that the concentricity of the rear cylinder and the slide bearing 12 cannot be obtained.

In the electromagnetic reciprocating compressor shown in FIG. 13,
Since the front piston 1A and the rear piston 1B formed at the front and rear portions of the piston body 1 oscillate as sliding portions, unless the inner surface of the slide bearing 12 is machined with high precision, the piston body 1 Not enough cylinders 2, 11 to expect a smooth reciprocation of 1.

Therefore, in the conventional molding method, the inner surface of the slide bearing 12 must be processed again after molding the rear cylinder, which is troublesome.

For example, when the slide bearing 12 is made of aluminum die-cast, the surface of the slide bearing 12 must be subjected to an insulation treatment (for example, an alumite treatment), so that the manufacture of the slide bearing 12 is further complicated.

The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a method for performing injection molding of a cylindrical product requiring high precision on the inner peripheral surface thereof with a resin. For example, a method of molding a cylindrical resin product which does not deform the slide bearing 12), is easy to perform the centering process, and can accurately match the axes of the parts to be fitted with each other, and a method of molding the resin product An object of the present invention is to provide a male mold for molding.

(Means and Actions for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a method for mounting a cylindrical male mold on a cylindrical female mold for injection molding. In the method for molding a resin product by molding a cylindrical product from the resin charged in the male mold, the male mold is urged in the centrifugal direction to maintain the inner peripheral surface shape and dimensions of the cylindrical forming product uniform as desired. By using the male mold, at least until the resin filled between the female and male molds is cured, the cylindrical body having a perfectly circular cross section is uniformly pressed from the inner peripheral surface side of each part, and It is characterized in that a cylindrical body having a perfectly circular cross section is integrally molded with the inner peripheral surface of the molded product. Thereby, at least at the time of curing of the resin, the gap between the cylindrical body and the male mold supporting the cylindrical body is removed.

Further, the present invention provides, as a member for supporting the cylindrical body,
At least a portion of the inner peripheral surface corresponding to the length dimension of the cylindrical forming product is formed so as to have a gentle tapered surface,
A collet shaft in which a plurality of split grooves alternately extend in the axial direction from both end portions thereof, and which is arranged inside the collet ring and has at least a part of its outer diameter formed in a tapered shape. It is also characterized in that a male mold for molding a cylindrical resin product is configured so that the inner surface of the collet ring can be pressed by sliding in the axial direction. By pressing the inner surface of the collet ring, the outer surface dimension of the collet ring increases, and the cylindrical body can be pressed uniformly from the inner surface.

Further, the present invention is characterized in that a magnet for adsorbing a ball disposed on the bottom of the cylindrical mold is attached to the tip of the core head inserted into the axis of the collet shaft. By attracting the ball to the magnet, the ball can be easily supported.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a longitudinal sectional side view showing a first embodiment of a mold for molding a cylindrical resin product, that is, a movable male mold 100 according to the present invention.
FIG. 2 is a longitudinal sectional side view showing the configuration of a female mold that forms a pair with the metal mold shown in FIG.

The pair of movable male mold 100 and the fixed female mold 200 shown in FIGS. 1 and 2 correspond to the pair of molds shown in FIG. Will be described.

Of the components constituting the movable male mold 100, the core 30,
A perspective view of the collet shaft 40 and the collet ring 50 is shown in FIGS. 3 to 5, and the core 30 shown in FIG.
Comprises a core shaft 32, a core head 31 formed at one end of the core shaft 32, and a male screw 33 formed at the other end of the core shaft 32. The core head 31
Is set to a dimension that allows the slide bearing 12 to be inserted.

A ball holding member 34 is buried at the tip of the core head 31. The ball holding member 34 is a magnet, and is a cylindrical product to be molded, that is, a ball fixed to the bottom of the rear cylinder (the ball shown in FIG. 13).
The spherical concave portion 34A is formed to be slightly shallower than the radius of the ball 13 so that 13) can be held.

The collet shaft 40 shown in FIG.
Is a cylindrical body having a cylindrical hole 44 for inserting the collet shaft 32, the outer periphery of which is a tapered portion having a gentle gradient.
41 (a steeply conical portion) and a straight portion 42 (cylindrical portion) having the same outer diameter are formed. Tapered part 41
Are formed such that the outer diameter dimension gradually increases toward the end of the collet shaft 40.

A male screw 43 is formed at an end of the straight portion.

Note that, in the figure, reference numeral S1 indicates the length of the tapered portion 41.

The collet ring 50 shown in FIG. 5 has a cylindrical shape whose outer peripheral surface is formed in a cylindrical shape having the same diameter in each part, and whose inner peripheral surface is formed in a tapered portion 53 whose one end has an inner diameter slightly smaller than the other end. Shape. The gradient of the tapered portion 53 is set to be the same as the gradient of the tapered portion 41 of the collet shaft 40.

As shown in the figure, the collet ring 50 is formed with split grooves 51 and 52 alternately from both ends. At the ends of the split grooves 51 and 52, circular break stoppers 51A and 52A are formed to relieve stress concentration occurring at the ends.

Again, in FIG. 1, the core 30 is inserted into the collet shaft 40 from the tapered portion 41 side of the collet shaft 40, and the collet shaft 40 is inserted into the straight portion 42 thereof.
Insert the collet ring 50 from the side. This insertion is performed such that the inclination directions of the tapered portion 41 and the tapered portion 53 of the collet ring 50 match.

A hole 62 having a diameter larger than the outer dimension of the straight portion 42 of the collet shaft 40 is formed in the base 60, and a protrusion 61 is planted on one surface thereof. The length of the protrusion 61 is set to be the same as the depth of a concave portion 201B described later with reference to FIG.

A positioning plate 90 is fixed to the other surface of the base 60.

The positioning plate 90 is formed with a positioning hole 91 having an inner diameter substantially the same as the outer diameter of the straight portion 42.

Next, the straight part 42 side of the collet shaft 40 is inserted into the hole 62 formed in the base 60 from the side where the positioning plate 90 is not fixed. Thereby, the straight portion 42 is inserted into the positioning hole 91, and the collet shaft
The positioning of the 40 with respect to the base 60 is performed.

Thereafter, the disc springs 81 and 82 are arranged between the positioning plate 90 and the male screw 43 of the collet shaft 40, and the pushing tool is pushed out.
The female screw 72 formed on the screw 70 is screwed. At this time, the push pins 71 planted on the pusher 70 are inserted into the holes 63 formed in the base 60.

 Finally, a nut 80 is screwed into the male screw 33 of the core 30.

In the state shown in FIG. 1, the disc spring 81 and
The pusher 70 is pressed in the direction of the nut 80 by the elastic force of 82 and is in contact with the nut 80. As a result, the push pin
Reference numeral 71 denotes a retracted state in the base 60 or a state flush with the surface of the base 60, and the tapered portion 41 of the collet shaft 40 moves in the direction of the extruder 70 between the collet ring 50 and the core 30. Then, the tapered portion 41 uniformly presses the tapered portion 53 on the inner surface of the collet ring 50 (in the direction of arrow D), so that the outer diameter of the collet ring 50 becomes large.

 In the following description, this state is called an operating state.

During the period from this operating state to an initial state described later, the collet shaft 40 and each part are so arranged that the boundary between the tapered part 41 and the straight part 42 is located in the hole 62 of the base 60. The dimensions have been set.

In this operating state, the pusher 70 is
Since it is pressed in the direction of 80 and is in contact with the nut 80,
By changing the screwing position of the nut 80, the positions of the pusher 70 and the collet shaft 40 can be adjusted, and the retreat position of the push pin 71 and the outer diameter of the collet ring 50 in the operating state can be adjusted.

Now, the movable male mold 100 configured as described above is the sixth male mold.
As shown in the figure, by pushing the pushing tool 70 in the direction of arrow A, the push pin 71 projects from the base 60. At this time, the collet shaft 40 is connected to the core 30 and the collet ring.
The collet ring 50 slides between them, and the pressing force of the taper portion 41 against the taper portion 53 on the inner surface of the collet ring 50 is reduced, and the collet ring 50 is reduced in diameter by its elasticity.

 In the following description, this state is called an initial state.

In this initial state, the outer diameter of the collet ring 50 is substantially the same as or smaller than the outer diameter of the core head 31. The dimensions of each part of the movable male mold 100 are set so as to be substantially the same as or larger than the inner diameter of the twelve.

 Next, the fixed female mold 200 will be described.

As shown in FIG. 2, the fixed female mold 200 has a recess having a cylindrical outer shape of a rear cylinder to be injection-molded.
201A and a concave portion 201B having a shape corresponding to the outer shape of the flange of the rear cylinder. A resin injection port 202 is formed at the bottom of the recess 201A.

Movable male mold 100 and fixed female mold 200 having the above configuration
Next, a method of injection molding a rear cylinder using the method will be described.

FIGS. 7 to 10 are diagrams for explaining the resin product molding method in the order of steps. In FIGS. 7 to 10, the same or equivalent parts as those in FIGS. 1 to 6 are designated by the same reference numerals. Is shown.

First, as shown in FIG. 7, the pusher 70 is pushed in the direction of arrow A to bring the movable male mold 100 to an initial state. Then, when the outer diameter of the collet ring 50 is reduced, the plain bearing 12 whose at least its inner surface is precisely molded is mounted on the collet ring 50 (direction of arrow B).
In addition, a metal reinforcing ring 301 is mounted on the protrusion 61 planted on the base 60. The reinforcing ring 301 is for reinforcing a screw hole (a hole into which the male screw 15 shown in FIG. 13 is inserted) formed in the flange of the rear cylinder to be molded.

Further, the ball 13 is brought into contact with the concave portion 34A and is attracted to the ball holding member 34.

Next, as shown in FIG. 8, the pressing by the pusher 70 is stopped, and the pusher 70 is restored in the direction of arrow B by the elastic force of the disc springs 81 and 82. That is, a movable male mold
The outer diameter of the collet ring 50 is increased by setting 100 to the operating state. As a result, the sliding bearing 12 is more firmly held by the pressing of the collet ring 50 than its inner surface, and the clearance between the sliding bearing 12 and the collet ring 50 is eliminated.

In this state, the movable male mold 100 is moved in the direction of arrow A, and the movable male mold 100 is inserted into the fixed female mold 200.

The axis of the inserted movable male mold 100 completely matches the axis of the fixed female mold 200, and a gap of a required width is formed between the two molds 100 and 200. To this end, resin is injected from the injection port 202 of the fixed female mold 200 as indicated by an arrow C in FIG. This state is maintained until the injected resin is cured.

After the resin is cured, as shown in Fig. 10, the movable male mold
100 is retracted in the direction of arrow B, the rear cylinder 300 formed by injection molding is taken out of the fixed female mold 200 together with the movable male mold 100, and then the pushing tool 70 is pushed in the direction of arrow A in FIG. The molded rear cylinder 300 is removed from the movable male mold 100, and the movable male mold 100 is set in an initial state. In this case, the outer diameter of the collet ring 50 is reduced, and the molded rear cylinder 300 is removed by the pushing operation of the push pin 71. FIG. 11 is a vertical sectional side view of the molded rear cylinder 300.

Until the resin is injected and hardened in this way, the movable male mold 100 is in the operating state, so that the sliding bearing 12 is firmly supported by the collet ring 50 from the inside thereof, and the sliding bearing 12 and the collet ring 50 are fixed. There is no clearance between them. Therefore, even if the resin shrinks when the resin is cured, the sliding bearing 12 may be deformed or the sliding bearing 12 may be deformed.
The concentricity between 12 and the cylindrical portion of the rear cylinder 300 does not shift.

In addition, when the slide bearing 12 is mounted on the movable male mold 100 and when the rear cylinder 300 is taken out after hardening, the outer diameter of the collet ring 50 holding the slide bearing 12 becomes small. And easy to take out.

Further, in this embodiment, the collet shaft 40
And the push pin 71 is fixed to the same pushing tool 70, and the operation of changing the outer dimensions of the collet ring 50 and the pushing operation of the push pin 71 are performed at the same time. It can be easily removed from the mold 100.

FIG. 12 is a longitudinal sectional side view showing a configuration of a second embodiment of a male mold for molding a cylindrical resin product according to the present invention, and shows an operating state similarly to FIG. 12, the same reference numerals as those in FIG. 1 denote the same or equivalent parts.

In FIG. 12, a tapered portion 441 formed on the collet shaft 440 is formed in a region indicated by reference numeral S2.

In addition, the inner diameter of the hole 462 formed in the base 460 is
The collet shaft 440 is formed to have almost the same outer diameter as the straight portion 442 of the collet shaft 440.

Furthermore, the tapered portion 4 on the inner surface of the collet ring 450
53 is formed only in the area indicated by the symbol S3. A portion 454 of the inner surface of the collet ring 450 other than the tapered portion 453 is formed in a cylindrical shape.

Now, in this embodiment, the collet shaft 440
Since the straight portion 442 is supported by the hole 462 of the base 460 having the same inner diameter as the outer size of the straight portion 442, the positioning plate 90 as shown in FIG. is there.

In addition, during the period from the operating state to the initial state of the movable male mold 400, the boundary between the tapered portion 441 and the straight portion 442 of the collet shaft 440 is, as shown in FIG. Since the dimensions of each part of the movable male mold 400 are set so as to be opposed to the straight part 454 of the ring 450, the movable male mold shown in FIG.
Press the pusher 70 in the same manner as
By sliding the 40 between the core 30 and the collet ring 450, the outer dimensions of the collet ring 450 can be reduced due to its elasticity.

In the above description, the collet ring 50, 450
The outer surface is formed in a cylindrical shape, and the inner surface thereof is formed in a tapered shape, and the tapered portions 41, 441 of the collet shafts 40, 440 are formed so as to have the same gradient as the inner surfaces of the collet rings 50, 450. However, the present invention is not particularly limited to this.

That is, in the initial state of the movable male molds 100 and 400, the outer peripheral surface of the collet ring 50 is not cylindrical with the same diameter, and the inner peripheral surface has the same gradient as the tapered portions 41 and 441 of the collet shafts 40 and 440. The collet rings 50 and 450 need only be in the above-described state at least when the movable male molds 100 and 400 are in operation. At least during the operation of the movable male mold 100, 400, the inner peripheral surfaces of the collet rings 50, 450 have the same gradient as the tapered portions 41, 441 of the collet shafts 40, 440,
In this case, if the outer peripheral surfaces of the collet rings 50 and 450 are cylindrical, the sliding bearing 12 to be supported by the collet rings 50 and 450 can be uniformly pressed from the inside.

In the above description, the collet shaft 40 or 440 and the push pin 71 are fixed to the same pushing tool 70,
Operation for changing the outer dimensions of the collet ring 50 and push pins
Although the pushing operation of 71 is performed at the same time, the present invention is not particularly limited to this, and it goes without saying that each operation may be performed separately.

Further, disc springs 81 and 82 are arranged between the base 60 or 460 and the pushing tool 70, and the movable male mold 100 or 400 is moved from the initial state to the operating state by the elastic force of the disc springs 81 and 82. Although the shifting is performed, the shifting operation between the initial state and the operating state may be entirely performed by an external force without providing the disc springs 81 and 82.

As described above, the present invention has been described by taking the case of molding the rear cylinder of the electromagnetic reciprocating compressor as an example. The present invention is applicable to the molding of any part or product.

(Effects of the Invention) As is clear from the above description, according to the present invention, the following effects are achieved.

(1) In the resin product molding method according to claim 1,
Even if the resin shrinks when it cures, there is no gap between the cylindrical body and the male mold that supports the inner peripheral side of the molded product,
The molded product is firmly supported by a male mold, and there is no room for deformation of the inner peripheral surface of the molded product requiring high precision molding. Therefore, even when the molded article is integrally molded with the cylindrical body, the concentricity between the cylindrical body and the resin product does not change at all, so that it is not necessary to rework the cylindrical body after molding, and the processing accuracy is reduced. This makes it easy to produce high-resin products.

(2) In the resin product molding die according to the second aspect, during the injection molding of the cylindrical resin product, the outer diameter of the collet ring that supports the inner peripheral surface side of the cylindrical body is adjusted to the size of the cylindrical body. Since each part can always be kept uniform according to the inner diameter dimension, the male mold can follow the peripheral temperature change in the cooling step after injection molding, and the cylindrical body can be deformed or The axis of the cylindrical body and the cylindrical resin product do not shift.

(3) In the resin product molding die according to the third aspect, since the ball can be easily fixed at the time of molding, it is easier to manufacture a cylindrical resin product which needs to fix and arrange the ball inside. Become.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view showing a configuration of an embodiment of a male mold (movable male mold) for molding a cylindrical resin product according to the present invention. FIG. 2 is a vertical sectional side view showing a configuration of a fixed female mold which forms a pair with the mold shown in FIG. FIG. 3 is a perspective view of the core. FIG. 4 is a perspective view of a collet shaft. FIG. 5 is a perspective view of the collet ring. FIG. 6 is a vertical sectional side view showing a state where the pusher of the movable male mold shown in FIG. 1 is advanced. 7 to 10 are longitudinal sectional side views for explaining a method for molding a cylindrical resin product according to the present invention in the order of steps. FIG. 11 is a vertical sectional side view showing a rear cylinder of a reciprocating compressor molded by the method of molding a cylindrical resin product of the present invention. FIG. 12 is a longitudinal sectional side view showing the configuration of another embodiment of a male mold (movable male mold) for molding a cylindrical resin product according to the present invention. FIG. 13 is a longitudinal side view of an electromagnetic reciprocating compressor having a rear cylinder. FIG. 14 is a schematic view for explaining a conventional molding technique for injection-molding the rear cylinder with a resin. 12 ... Slide bearing, 13 ... Ball, 30 ... Core, 31 ...
Core head, 32: Core shaft, 34: Ball holding member, 34A: Recess, 40,440 ... Collet shaft, 41, 44
1 ... taper part, 42,442 ... straight part, 44 ... cylindrical hole, 50, 450 ... collet ring, 52, 52 ... split groove, 51
A, 52A …… Cleaning prevention, 53,453 …… Tapered part, 60,460 ……
Base, 62,462 ... Hole, 63 ... Hole, 70 ... Extruder, 71
…… Push pin, 80 …… Nut, 81,82 …… Belleville spring, 90…
... Positioning plate, 91 ... Positioning holes, 100,400 ... Movable male mold, 200 ... Fixed female mold, 300 ... Rear cylinder

Claims (3)

(57) [Claims] 1. A cylindrical male mold is mounted on a cylindrical female mold for injection molding, and the resin filled between the male and female molds is
A method for molding a resin product in which a cylindrical product is molded integrally with a cylindrical body having a true circular cross-section, wherein centrifugation is performed so that the inner peripheral surface shape and dimensions of the cylindrical forming product are uniformly maintained as desired. Using a male mold that is urged in the direction, the male mold is used, and at least until the resin filled between the female and male molds is cured, the cylindrical body having a perfectly circular cross section is formed on the inner peripheral surface thereof. A method for molding a cylindrical resin product, comprising uniformly pressing each part from the side and integrally molding a cylindrical body having a perfectly circular cross section on the inner peripheral surface of the molded product. 2. A male mold for molding a cylindrical resin product, wherein a cylindrical component having a cylindrical body processed on a highly accurate inner peripheral surface is injection-molded with a resin. A portion corresponding to the length dimension of the cylindrical forming product is formed so as to have a gentle tapered surface,
And a collet ring in which a plurality of split grooves alternately extend in the axial direction from both ends thereof, and a portion corresponding to at least the length dimension of the outer peripheral surface is formed into a tapered surface that is gently inclined at substantially the same angle in the opposite direction. A male mold for molding a cylindrical resin product, comprising: a formed collet shaft; and means for pulling the collet shaft in the axial direction with respect to the collet ring. 3. A magnet attached to a tip of a core head inserted into an axis of the collet shaft, the magnet being attached to a bottom portion of a cylindrical mold. Male mold for molding cylindrical resin products.