JPH0243695Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field of the Invention) The present invention relates to a mold for molding a rubber roll such as a heat roll used, for example, in a heat fixing section of an electronic copying machine.

(Technical background of the invention and its problems) Conventionally, in order to manufacture rubber rolls such as heat rolls used in the heat fixing section of electronic copying machines by injection molding method or compression molding method, the method shown in Fig. 1 is as follows. As shown, there is a mold body 1 that is divided into upper and lower halves and has a cylindrical molding part, and a mold body 1 that has a bearing hole 2 on the end surface.
A molding die 4 consisting of a pair of core shaft holding caps 3 inserted into both ends of a cylindrical molded part with the bearing hole 2 facing inward is used to hold the hollow core shaft 5 of the rubber roll at both ends. The rotating shaft part 6 is inserted into the bearing hole of the core shaft holding cap 3 and inserted into the mold body 1, and a cylindrical cavity formed between the inner peripheral surface of the mold body 1 and the core shaft S is formed. A method is adopted in which liquid rubber 8 is press-fitted from an injection path 7 provided in the mold body 1.

By the way, in such a method, as the liquid rubber 8 is press-fitted, the air inside the cylindrical cavity is forced out from the joint surfaces of the upper and lower molds 9 and 10.
In a mold having an injection path 7 in the upper part of the cavity, particularly in the end of one side of the mold body 1, the air in the upper part of the cavity on the opposite side is difficult to be pushed out and tends to remain as a void 11 even after filling with the liquid rubber 8. There was a problem.

In order to solve this problem and form a void-free rubber roll, conventional methods include attaching a vacuum device and press-fitting liquid rubber while sucking the air inside the cavity, and using a core holding method as shown in Figure 2. A groove 12 for a rubber reservoir is provided on the side circumferential surface of the cap 3.
A method is being used to draw residual air into this area.

However, the former method has the drawbacks that the vacuum device is expensive, cleaning is troublesome, and the molding cycle becomes longer.In the latter method, the upper and lower molds 9 and 10 are removed after molding. There was a drawback that the end of the rubber roll was easily chipped when the shaft holding cap 3 was removed.

(Purpose of the invention) The present invention was made in order to eliminate these drawbacks, and its purpose is to provide a molding die that can mold void-free rubber rolls at low cost and in a short cycle. .

(Summary of the invention) The mold for molding rubber rolls of the present invention has grooves running in the axial direction formed on the inner peripheral surface of the upper mold which is in contact with the peripheral surface on the side of the cap for holding the core shaft. It is characterized in that a notch is provided along the entire circumference of the outer peripheral edge of the core shaft holding cap, and a groove communicating with the notch is provided in the joint surfaces of the upper and lower molds.

In the present invention, the groove in the upper mold, the cutout in the core shaft holding cap, and the groove in the joint surface of the upper and lower molds form a communication path for completely expelling the air in the cavity of the mold body to the outside. Form. If the liquid rubber injection path is provided at one end of the mold body, such a communication path will be provided only on the opposite side far from the injection path, and if the injection path is provided in the center, it will be provided on both sides. Provided for.

(Embodiments of the invention) Examples of the invention shown in the drawings will be described below. FIG. 3 is a partial vertical sectional view of an embodiment of the present invention.

In this figure, reference numeral 13 indicates a mold for molding a rubber roll, which has a cylindrical molding part and a mold body 14 that is divided into upper and lower halves and has a liquid rubber injection path formed at one end (not shown). Roll core shaft 1 on end face
It has a bearing hole 17 for supporting the rotating shaft part 16 of No. 5,
It is comprised of a pair of core shaft holding caps 18 inserted into both ends of the cylindrical molded part of the mold body 14 with the bearing hole facing inward.

The part of the mold body 14 that comes into contact with the side peripheral surface of the core shaft holding cap 18 inserted into the end of the inner peripheral surface of the upper mold 19 that is far from the injection path is provided with an appropriate width in the axial direction. A groove 20 is formed, and a notch 21 is provided along the entire circumference of the outer peripheral edge of the core shaft holding cap 18 on the same side.

Furthermore, a groove 23 communicating with the outside is provided on the joint surface of the upper mold 19 with the lower mold 22 that is connected to the notch 21.
is provided.

According to the molding die 13 configured in this way, as the liquid rubber press-fitted from the injection path fills the cylindrical cavity, the air in the cavity is forced to flow into the inner circumferential surface of the upper die 19. It passes through the groove 20 of the lead shaft holding cap 18, passes through the notch 21 of the core shaft holding cap 18, and further passes through the groove 23 of the joint surface of the upper mold 19 and escapes to the outside in the direction of the arrow, far from the injection path where it is particularly likely to remain. Since the air above the cavity is also quickly pushed out through this communication path, a void-free rubber roll can be formed.

(Effect of the invention) As is clear from the above explanation, the rubber roll forming mold of the invention has an air vent passage communicating with the outside near the upper end of the cavity where air is most likely to remain. , it is possible to form high-quality rubber rolls with absolutely no voids.

[Brief explanation of the drawing]

Fig. 1 is a partial vertical cross-sectional view showing a method of forming a rubber roll using a conventional molding die, Fig. 2 is a partial vertical cross-sectional view of another conventional molding die, and Fig. 3 is a partial longitudinal cross-sectional view showing the method of forming a rubber roll using a conventional molding die. FIG. 2 is a partial vertical cross-sectional view of one embodiment of the invention. 1, 14... Mold body, 2, 17... Bearing hole, 3,
18... Core shaft holding cap, 5, 15... Roll core shaft, 6, 16... Rotating shaft portion, 9, 19... Upper mold, 1
2...Groove for rubber reservoir, 20, 23...Groove, 21...Cutout part.

Claims (1)

[Scope of utility model registration request] A mold body having a cylindrical molding part and having a liquid rubber injection path communicating with the cylindrical molding part, which is divided into upper and lower halves, and a bearing hole for supporting the rotating shaft part of the roll core shaft in the end surface, In the molding mold, the mold body includes a pair of core shaft holding caps inserted into both ends of the cylindrical molding part of the mold body with the bearing hole facing inward, the core shaft on the inner peripheral surface of the upper mold. A groove is formed in the axial direction at the contact portion with the side circumferential surface of the holding cap, and the outer circumferential edge of the core shaft holding cap is cut out over the entire circumference, and a groove is formed in the joint surface of the upper and lower molds. A mold for molding a rubber roll, characterized in that a groove is provided that communicates with the notch.