JPS5991014A - Manufacture of mold for plastic gear - Google Patents

Abstract

PURPOSE:To manufacture tooth form simply and to finish it efficiently and precisely by dividing a circular mold material into a plurality of segmental molds. CONSTITUTION:A mold material is divided radially into four segments and the inner circumferential surface of each segmental mold 2 is ground by a gear- tooth forming grinder 3 to provide a tooth form 6 consisting of a crest part 4 and a trough part 5. Grinding is carried out so that the crest parts 4, 4 or a trough part 7a of a plastic gear 7 are positioned on segmental surfaces 2a, 2a of segmental molds 2... and pins 8, 8 are plunged into the mold surface of each segmental mold 2. The segmental molds 2... are assembled in a circular form, mounted on the end of the mold body 9 and fixed with the pins 8, 8, then a mold 11 having a gear type cavity 10 is obtained. In this case, the tooth form is always made constant on the crest part 7b of the plastic gear 7 and the joining parts of the segmental molds 2 do not exert any adverse effect on the profile and the surface roughness of the crest part 7b of the plastic gear 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] This invention relates to a method for manufacturing a plastic gear mold for use in molding plastic gears by injection molding.

[Technical background of the invention and its problems]

As shown in Fig. 1, a molding die for molding plastic precision gears used in copying machines, etc. has a gear-shaped cavity b formed in a mold body a.
As a means for forming b, it is common to use a gear-shaped electrode and perform electrical discharge machining or electrolytic machining.

However, as mentioned above, the gear-shaped cavity (b is the surface roughness of the south surface of the mold body a made of #iPt, and the tooth profile shape is affected by the accuracy of the electrodes) are prepared.
Gradually process the electrode while replacing it with a new one, or use a gear-shaped cavity (b) after machining or loose machining.
The rh surface of the shaft is machined. Therefore, it is very difficult to process the gear-shaped cavity b, especially since the tooth profile of the gear-shaped cavity b is formed on the inner circumferential surface of the hollow mold body a. Post-processing was extremely difficult and caused zero cost savings.

[Purpose of the invention]

This invention was made in view of the above-mentioned circumstances, and its purpose is to be able to finish the surface roughness of the tooth surface of a gear-shaped cavity with high accuracy and the tooth profile shape, and to reduce costs by being easy to manufacture. 11 plastic gear molds that can achieve this! ! This is an attempt to improve the way the system is used.

[111° of the invention (required) pJ 1xIj-shaped mold; (1 inch 4 is divided in the radial direction to form a plurality of divided molds, and the inner circumferential surface of these divided molds is shaped like a 100-wheeled mold ( In addition to grinding with a 11L stone, during this 11J1 grinding, the bottom of the tooth of the 0ns stick M wheel becomes the above-mentioned dividing surface to prevent an adverse effect on the tooth profile shape and tooth surface surface roughness caused by the joint, and the above-mentioned split type The objective is to form a gear-shaped key Y-bibooy by integrally combining the two.

[Embodiments of the invention]

The present invention will be described below based on an embodiment shown in the drawings. Figure F2 (A) (It) (C) (1)) shows the manufacturing method of the plastic float forming mold.
is a ring-shaped metal mold. This mold 1 is rotated and divided into four in the radial direction to form four divided molds 2. Next, the inner circumferential surface of each of the split molds 2 is ground by an FFR wheel forming grindstone 3 to form a tooth surface 6 consisting of peaks 4 and valleys 5. At this time, the dividing surface 2 of the dividing die 2...
A, 2a are ground so that the crests 4, 4-J-, that is, the tooth bottoms 7a of the plastic floats 7 shown in FIG. Plant 8.

In this way, after forming tooth surfaces 6 on each division °λ1, 122... by grinding, they are placed on the end face of the mold body 9, and the respective division molds 2... are combined into an annular shape to form a bin 8. By fixing at an angle of 8°, a molding die 11 having a gear-shaped cavity 10 is obtained. In this case, the peaks 4, 4 of the tooth surfaces 6 are located on the split surfaces 2a, 2a of each split mold 2 and are in contact with each other, so that the joint portion is the tooth bottom 7a of the plastic gear 7. (i9) The tooth profile shape at the peak part 7b of the plastic gear 7 is always constant, and the split type 2...
The joint portion of * does not adversely affect the shape and surface roughness of the peak portion 7b of the plastic gear 7.

In the above-mentioned embodiment, the split mold is fixed to the mold body with a pin, but as shown in FIG. 12 kj, it may be fixed to the mold body with a spigot.

〔Effect of the invention〕

As explained above, this invention is easy to manufacture because the annular mold is formed into a plurality of divided molds, and the tooth surfaces of these divided molds are ground using a gear-creating grindstone. At the same time, the f11 surface can be finished more efficiently and with higher precision than conventional electrical discharge machining or electrolytic machining. Furthermore, by forming the tooth surface so that the tooth bottom of the plastic gear becomes the joint surface of the split die,
J-1, shadow Qlp can be prevented, viscosity of tooth profile, peak f
This has the effect of making it possible to improve the level of illiness.

[Brief explanation of drawings]

Fig. 2 is a perspective view of a molding die from IC, Fig. 2<A) to θ)) is a plan view and a perspective view showing an embodiment of the manufacturing method of this invention, and Fig. 3 is a perspective view of a molding die from IC. tick gear t'
FIG. 4 is a perspective view showing another embodiment of the split type. 1...Mold material, 2...Divided mold, 3...Gear creation grindstone, 7...Plastic gear, 7a...Tooth bottom, 1
θ...Gear-shaped cavity.

Claims (1)

[Claims] Those who manufacture molds for molding glass gears
In this method, a ring-shaped mold wood is divided in the radial direction to form multiple split molds, and the inner circumferential surface of these split molds is shaped like a gear n so that the peak of the plastic gear becomes the dividing surface.
Manufacturing a mold for molding a F0 plastic N: 1 car, which is characterized by mainly forming a Yushin-shaped V-bite (-111 grinding with a grinding wheel) (-7, then combining the above-mentioned split molds integrally) Method.