JPH07125026A - Mold apparatus - Google Patents

Abstract

PURPOSE:To enable compression molding generating no scoring of a mold piece, for example, even when a long lens is molded. CONSTITUTION:A mold apparatus is equipped with a mold main body, the mold piece 11 fitted to the mold main body in a freely slidable manner and having a molding surface and a non-circular cross-sectional shape and the compression rod 16 fitted to the mold main body in a freely slidable manner and allowing the mold piece 11 to slide with respect to the mold piece in order to subject a synthetic resin material to compression molding between other molding surface 13 and the molding surface 14 and having a circular cross-sectional shape and, with respect to the temp. of a mold at the time of molding, the fitting gap between the mold main body and the compression rod 16 is set to 0.001-0.015mm and that between the mold main body and the mold piece 11 is set to 0.002-0.030mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die device used for manufacturing parts made of synthetic resin.

[0002]

2. Description of the Related Art Injection molding, injection compression molding, compression molding and the like have been conventionally known as methods for manufacturing plastic parts. However, for parts requiring high transferability and high shape accuracy, injection compression molding or A manufacturing method such as compression molding in which a compression operation is performed during molding is applied. Optical components such as lenses, prisms, and focus plates are examples of components that require high transferability and high shape accuracy. Generally, lenses and prisms are manufactured by injection compression molding, and focus plates are manufactured by compression molding.

[0003]

Here, an example of a conventional mold apparatus used for injection compression molding of a lens will be described with reference to the drawing of the mold apparatus according to the embodiment of the present invention shown in FIG. To do. In this description, portions having the same functions as those in the embodiment are represented by the same reference numerals, and the reference numerals are attached with ′ to distinguish them from the constituent members of the embodiment.

In a conventional mold device, a mold piece 11 'for compression-molding a plastic material and a mold piece 12' where the mold piece 11 'is slidably held are formed. In order to prevent galling during sliding of 11 'in the compression operation, the cross section of the mold piece 11' is usually circular. Therefore, there is no particular problem when molding a component having a circular lens surface as shown in FIG. 6, but when molding a prism 31 or the like as shown in FIG.
As described in Japanese Patent No. 78305, a quadrangle originally,
A sliding portion 32 having a circular cross section is provided on a portion of an optical surface (mirror surface) having a polygonal shape such as a triangle and the portion is compressed. Therefore, if the shape of the molded product is restricted and the optical surface has a polygonal shape substantially close to a circular shape, the outer diameter of the mold piece covers the effective portion of the optical surface, which is still preferable.
In the case of a long lens as shown in (1), since the effective portion of the optical surface is elongated, there is a problem that the outer diameter of the mold piece cannot cover the entire optical surface. Therefore, when molding such a long lens, the cross-sectional shape of the mold piece to be slid cannot be circular, and it is impossible to perform injection compression molding without causing scratches. It was forced to manufacture by injection molding which does not do.

Therefore, the present invention has been made in view of the above-mentioned problems, and an object thereof is to enable compression molding without galling of a mold piece even when molding a long lens or the like. It is to provide a mold device.

[0006]

In order to solve the above-mentioned problems and to achieve the object, a mold device of the present invention comprises a mold body and a molding surface slidably mounted on the mold body. A mold piece having a cross-sectional shape that is not circular, and the mold piece on the mold body in order to compression-mold a synthetic resin material between the molding surface and another molding surface. A compression rod which is slidable relative to the mold body, the compression rod being slidably mounted on the mold body and having a circular cross section.
At the mold temperature at the time of molding, the fitting gap between the mold body and the compression rod is set in the range of 0.001 mm to 0.015 mm, and the fitting gap between the mold body and the mold piece is 0. It is characterized by being set in the range of 0.002 mm to 0.030 mm.

Further, the mold apparatus according to the present invention is characterized in that at least one of the sliding surface of the mold piece and the sliding surface of the mold body is surface-treated.

Further, the mold apparatus according to the present invention is characterized in that an oilless metal is attached to a portion of the mold body on which the compression rod slides.

Further, in the mold apparatus according to the present invention, the cross-section of the mold piece is polygonal, and the corners of the polygon are rounded.

[0010]

As described above, since the mold apparatus according to the present invention is configured, the sliding of the mold piece in the compression direction is guided mainly by the fitting of the compression rod and the mold body, and the mold piece and the metal mold are guided. By making the fitting gap between the die body and the compression rod slightly larger than the fitting gap between the compression rod and die body, even if the die piece is not circular in cross section, It is possible to use a mold piece having a shape close to that of a molded product without causing galling, and it is possible to perform compression molding even with a long lens or the like.

Further, at least one of the sliding surfaces of the mold piece and the mold body is subjected to a surface treatment, or an oilless metal is used for the mold part where the compression rod is fitted, or a corner part of the mold piece is used. By taking a method such as attaching R, it is possible to further improve the galling prevention effect of the mold piece whose cross-sectional shape is not circular.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an injection compression molding die apparatus which is one of the die apparatuses used for molding with compression according to an embodiment of the present invention, which is the laser shown in FIG. A mold device 100 used for molding a long lens called an fθ lens used in a scanning optical system.

In FIG. 1, reference numeral 1 is a fixed side mounting plate,
2 is a movable side mounting plate, 3 is a fixed side template, 4 is a movable side template,
Reference numeral 5 is a receiving plate, 6 is a spacer block, and 7 and 8 are ejector plates. Reference numeral 9 indicates a fixed side mold piece, and 11 indicates a movable side mold piece. The molding surfaces indicated by 13 and 14 are mirror surfaces, and mold the optical surface of the fθ lens which is a molded product. It is done like this.

The movable side mold piece 11 is housed in a holding piece 12 which is a mold body. Here, the fixed side mold piece 9, the movable side mold piece 11, and the holding piece 12 are hardened by heat treatment. The brim portion 1 which is a portion which is not the optical surface of the fθ lens
5 is formed by the holding piece 12. The space surrounded by the holding piece 12, the molding surface 13 of the fixed mold piece 9 and the molding surface 14 of the movable mold piece 11 is a cavity 10.
The resin material filled in is molded to form an fθ lens.

A piston 29 of a hydraulic cylinder 17, which is a compression device, is provided on the mold opposite to the cavity side of the movable mold piece 11.
The compression rod 16 provided at the tip of the is abuttingly connected. The compression rod 16 has a circular cross section, and is slidably guided with respect to the receiving plate 5 by an oilless metal bush 18 fitted therein. As the piston 29 of the hydraulic cylinder 17 advances, the movable mold piece 11 advances via the compression rod 16, and the cavity 10 is compressed.

An example of molding in the mold apparatus as described above will be shown below.

The mold apparatus 100 shown in FIG. 1 is attached between platens (not shown) of an injection molding machine, and the mold is clamped, and the resin is heated and melted in an injection cylinder (not shown), It is injected into the mold apparatus 100 shown in FIG. In addition,
The mold device 100 includes a water tube hole 24 for controlling the mold temperature in advance.
A temperature control medium is flown through a mold temperature controller (not shown) to control the temperature of the mold to a desired temperature (95 ° C. in this embodiment).

In this embodiment, acrylic (PMM
A) Resin is used and the set temperature of the injection cylinder is 250 ° C.
And The resin injected from the injection cylinder is sprue 2
0, runner 21, gate 22 and cavity 10
Flow to. After the resin is filled in the cavity 10 and injection pressure (600 kg / cm ² in this embodiment) is applied, a signal is sent to the hydraulic control device 19 to inject oil into the rear hydraulic chamber 25 of the hydraulic cylinder 17. The piston 29 of the hydraulic cylinder 17 is advanced. Thereby, the compression rod 16
Is moved forward, and the movable side mold piece 11 is moved forward,
The cavity 10 is compressed.

In this embodiment, the compression pressure is 500 kg / cm ² . After a compressive force is applied for a predetermined time (3 minutes in the present embodiment), a signal is sent to the hydraulic control device 19 to release the hydraulic pressure, and after a further predetermined time, the mold apparatus 100 is moved to the parting line 27. It is separated into a fixed side and a movable side. Then, the ejector rod (not shown) of the injection molding machine moves forward, the ejector plates 7 and 8 move forward accordingly, and the forward movement of the ejector pin 23 releases the molded product from the mold. After that, the mold is clamped again, and the next new molten resin is injected into the mold. In the present embodiment, the above-mentioned one cycle process requires about 8 minutes.

In addition to the mold clamping operation, the hydraulic control device 1
9 is sent to the front hydraulic chamber 26 of the hydraulic cylinder 17.
Oil is injected into the cylinder and the piston 29 of the hydraulic cylinder 17 is retracted. As a result, the compression rod 16 and the movable side mold piece 11 are retracted to the predetermined positions shown in FIG. 1, and the volume of the cavity 10 is adjusted as shown in FIG. 1 before the next molten resin is injected into the cavity 10. Be made bigger.

In the conventional mold device, the movable side mold piece 11 '(corresponding to the movable side mold piece 11 in FIG. 1) and the holding piece 1
The clearance with 2 '(corresponding to the holding piece 12 in FIG. 1) is set narrow, and the clearance is set wide in other places. That is, the movable side mold piece 11 'and the holding piece 12' were allowed to escape so as not to come into contact with each other except the sliding surface. However, the cross-sectional shape of the mold piece 11 'is not circular, so that the problem of "galling" occurs. The reason is that the movable mold piece 1 of the holding piece 12 'is
Since the hole into which 1'is inserted is not circular, it is difficult to improve the machining accuracy, and it is difficult to align the sliding center of the piston 29 'of the hydraulic cylinder 17' with the center of the hole of the holding piece 12 '. It can be mentioned. If the centers of the movable mold piece 11 'and the hugging piece 12' are not aligned, a component force perpendicular to the sliding direction is generated, and the movable mold piece 11 'is slid while being pressed against one side. Is likely to occur.

In this embodiment, a compression rod 16 having a circular cross section extended from the piston 29 of the hydraulic cylinder 17 is provided on the side opposite to the cavity surface of the movable mold piece 11 having a non-circular cross section. The movable side mold piece 11 and the holding piece 1 are connected and connected to each other to narrow the clearance between the compression rod 16 and the mold part to which the compression rod 16 is fitted.
The clearance between the compression rod 16 and the compression rod 16 is set to be wider than the clearance between the compression rod 16 and the mold portion with which the compression rod 16 is fitted. This prevents the movable side mold piece 11 from being bitten by the holding piece 12.

The inventors of the present invention conducted a detailed study and found optimum values of the clearance between the compression rod 16 and the mold part and the clearance between the movable side mold piece 11 and the holding piece 12. .

The clearance between the compression rod 16 and the die must be such that the compression rod 16 can move smoothly without rattling, and the movable side mold piece 11
Since there is no contact between the molding surface 14 that is a mirror surface that is an optical surface and the molding surface 13 that is a mirror surface that is an optical surface of the fixed-side mold piece 9, there is no eccentricity. Must be set. It has been found that the optimum clearance that satisfies this requirement is 0.001 mm to 0.015 mm (preferably 0.001 mm to 0.008 mm). The clearance between the movable mold piece 11 and the holding piece 12 is preferably as wide as possible from the point of galling, but if it is too wide, the clearance 28 between the movable mold piece 11 and the holding piece 12 is 28.
The molten resin enters into and becomes burrs. From this point, the clearance between the movable side mold piece 11 and the holding piece 12 is 0.002 mm.
~ 0.030mm (preferably 0.006mm ~ 0.020
The present inventor has found out from the detailed examination.

Needless to say, the clearance must be determined in consideration of the thermal expansion of the members forming the mold.

Concretely, for example, the clearance between the compression rod 16 and the mold part into which the compression rod 16 is fitted will be described as an example. The relationship between the material of each member and the coefficient of thermal expansion is as follows.

Name of each member Material of each member Thermal expansion coefficient of each member Compression rod 16 SKD11 12.0 × 10^-6 Bush 18 SUJ2 10.6 × 10^-6 Compression rod 16 and gold with which the compression rod 16 is fitted
The mold temperature near the mold is 95 ° C as described above.
The hole diameter at 95 ° C of the above-mentioned mold part is φ50 + 0.0
If 01-φ50 + 0.009, the compression rod 16
Shaft diameter at 95 ° C is φ50-0.006 to φ50 +
0, clearance is minimum 0.001mm ~ maximum
It should be 0.015 mm. Therefore, room temperature 2
The maximum shaft diameter of the compression rod 16 at 5 ° C is 50
-(95-25) x 12.0 x 10 ^-6× 50 = 49.9
58 mm, minimum 50-0.006- (95-25) x
12.0 x 10^-6X (50-0.006) = 49.95
2 mm, 49.960-0.008 to 49.96
It becomes 0-0.002. On the other hand, the compression rod 16
The maximum hole diameter of the mating mold at room temperature 25 ° C
At 50.09- (95-25) x 10.6 x 10^-6×
50.09 = 49.969 mm, minimum 50.001
-(95-25) x 10.6 x 10^-6× 50.001 =
49.964 mm, 49.960 + 0.004 ~
It becomes 49.960 + 0.009.

Further, if the clearance between the movable side mold piece 11 and the holding piece 12 is set as described above, the problem of galling can be eliminated. However, in order to solve the problem of galling, the inventors of the present invention move the movable side. At least one of the sliding surfaces 28 of the mold piece 11 and the holding piece 12, that is, the outer surface of the movable side mold piece 11, and the inner surface of the hole into which the movable side mold piece 11 is inserted in the holding piece 12 are provided. It has been found that it is important to increase the surface hardness (Hv (Vickers hardness) of 550 or more, preferably Hv of 600 or more) by performing the treatment. As surface treatment, electroless nickel plating (for example, phosphorus-containing nickel plating, boron-containing nickel plating, boron-tungsten-containing nickel plating, etc.), electroless cobalt plating (for example, phosphorus-containing cobalt plating, boron-containing cobalt plating, (Cobalt plating containing nickel and boron, cobalt plating containing nickel and phosphorus, cobalt plating containing boron and tungsten, cobalt plating containing phosphorus and tungsten, etc.)
, Chrome plating, TiN, TiCN, TiC, W ₂
There is a coating such as C, which may be selected in consideration of the material of the base material.

Further, in order to improve the slidability between the compression rod 16 and the mold part to which the compression rod 16 is fitted, if it is a normal sliding surface, a lubricant such as grease is applied. However, if grease or the like oozes into the cavity, it mixes into the molded product, causing problems such as transmittance in the case of optical parts, and problems with physical properties such as strength even with other parts,
The problem of adhesion of grease or the like may occur on the surface of the molded product.

Therefore, the inventors of the present invention have found that the bush 18 made of oilless metal is inserted into the mold portion to improve slidability without using grease or the like.
The oilless metal bush 18 and the compression rod 16
It is desirable that the fitting length between and is equal to or larger than the diameter of the compression rod 16. Further, it is desirable from the viewpoint of galling that the corner portion of the cross-sectional shape of the movable mold piece 11 that slides is rounded. The movable side mold piece 11 used in this embodiment has a shape as shown in FIG. 3, its cross-sectional shape is as shown in FIG. 4, and Rs of about R3 are attached to its four corners. Further, as shown in FIG. 5, the cross-sectional shape may of course be semicircular at both end surfaces.

By performing injection compression molding using the mold apparatus described above, the shape accuracy of the fθ lens of the laser scanning optical system shown in FIG. 2 is said to be within a molding error of 1 μm (within 3 Newton rings). A high-precision product was obtained, burrs did not occur, and galling of the mold piece did not occur even during long-term molding. On the other hand, when the conventional injection molding without compression is performed, the molding error is 5
It was impossible to reduce the thickness to less than μm (15 Newtons). Further, when injection compression molding was performed using a conventional mold in which the clearance between the movable side mold piece and the holding piece was set to a small value of 0.010 mm or less, galling occurred at about 20 shots from the start of molding, When it comes to shots,
It was impossible to perform the desired compression operation. (Other Embodiments) In the above-mentioned one embodiment, an example in which a hydraulic cylinder is incorporated as a compression device in the mold is shown, but a compression device provided separately from the mold clamping device is used in the molding machine. May be. Further, the compression device is not limited to hydraulic pressure, and may be driven by pneumatic pressure or a motor. In addition, although an example in which the mold temperature is kept constant is described in one embodiment,
By changing the mold temperature (when injecting the molten resin, set the mold temperature above the glass transition point of the resin, cool the resin after injection, and take out the molded product) to obtain higher precision in shape. It is possible to manufacture plastic parts with good quality.

Further, although the injection compression molding is described in the embodiment, the molding method involving compression can be applied as the same technique, and thus the compression molding method can also be applied.

In the embodiment, the molding of an optical component called a long lens has been described, but an optical component such as a prism other than the long lens may be used as long as it is a molding method involving compression. Further, needless to say, it is not limited to the optical component.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0036]

As explained above, according to the mold apparatus of the present invention, the sliding of the mold piece in the compression direction is guided mainly by the fitting of the compression rod and the mold body, and the mold piece and the mold are guided. By setting the fitting gap between the main body and the compression rod to be slightly larger than the fitting gap between the compression rod and the mold main body, even if the cross section of the mold piece is not circular, galling occurs between the mold piece and the mold body. It is possible to use a mold piece having a shape close to the shape of the molded product without causing the occurrence, and it is possible to perform compression molding even with a long lens or the like.

Further, at least one of the sliding surfaces of the mold piece and the mold body is subjected to a surface treatment, or an oilless metal is used for the mold portion where the compression rod is fitted, or the corner portion of the mold piece is By taking a method such as attaching R, it is possible to further improve the galling prevention effect of the mold piece whose cross-sectional shape is not circular.

[Brief description of drawings]

FIG. 1 is a view showing a structure of a mold device used for molding with compression which is an embodiment of the present invention.

FIG. 2 is a diagram showing a long lens used in a laser scanning optical system.

FIG. 3 is a perspective view of a movable mold piece.

FIG. 4 is a cross-sectional view of a movable mold piece.

FIG. 5 is a cross-sectional view showing another example of the structure of the movable mold piece.

FIG. 6 is a diagram showing a circular lens.

FIG. 7 is a diagram showing a penta prism.

[Explanation of symbols]

 10 Cavity 11 Movable Mold Piece 12 Holding Piece 16 Compression Rod 17 Hydraulic Cylinder (Compressor) 18 Oilless Metal Bushing 19 Hydraulic Control Device 29 Piston

Claims (4)

[Claims] 1. A mold piece having a mold body and a molding surface slidably mounted on the mold body, the mold piece having a non-circular cross section, and the molding surface and other parts. A compression rod that slides the mold piece with respect to the mold body in order to compression-mold a synthetic resin material between the mold surface and the mold rod, the cross-section being slidably mounted on the mold body. A circular compression rod is provided, and a fitting gap between the mold body and the compression rod is set in a range of 0.001 mm to 0.015 mm at a mold temperature at the time of molding. A mold device, wherein a fitting gap with the mold piece is set in a range of 0.002 mm to 0.030 mm. 2. The surface treatment is applied to at least one of the sliding surface of the mold piece and the sliding surface of the mold body on which the mold piece slides. Mold device described. 3. The mold apparatus according to claim 1, wherein an oilless metal is attached to a portion of the mold body on which the compression rod slides. 4. The cross-sectional shape of the mold piece is a polygonal shape,
The mold apparatus according to claim 1, wherein the corner portion of the polygon is rounded.