JPH036407Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the shape of a mold for forming an oil seal, and more specifically to the shape of a material injection mold that facilitates finishing of the inner lip of an oil seal.

A detailed description will be given below with reference to the drawings.

Conventionally, an oil seal 1 has been manufactured by using an upper mold A1 and a lower mold A2 as shown in FIG. The molded product thus produced was obtained by filling the cavity 2 with the elastic material C and applying compression to harden it. Since the burr flows out into the burr groove 3 around the burr and hardens as it is, finishing work must be performed to remove the burr, which is extremely troublesome and time-consuming. Furthermore, in the case of small-diameter oil seals 1, such as miniature seals used in miniature bearings, the inner diameter is so small that it is extremely difficult to physically finish the oil seals, and even mechanical removal has greatly hindered productivity. Furthermore, during this deburring and finishing work, it is easy to accidentally cut into the product side and cause scratches, which are difficult to visually check later.

The present invention aims to improve these drawbacks and provide an innovative oil seal molding die that can easily and reliably finish the inner diameter side during mold release in the molding process.

As shown in FIG. 2, the present invention is a material injection molding mold B for molding an oil seal 1 by injecting a material.
A material injection port 5 is provided on the inner periphery of the oil seal shaped cavity 2 of 1), which continues from the inner periphery to the material injection residue portion 4, and in addition, an acute-angled stepped notch 6 is provided at the gate portion of the inner periphery. It is characterized by a unique structure.

The mold structure described here is an injection method,
It is applicable to any type, such as a transfer type or a compression type, as long as it has a structure that allows material to be injected into the cavity 2.

With this structure, we obtained many effects such as the following. That is, to form the oil seal 1 in the material injection mold B, as shown in FIG. The material inlet 5
The molded product in this situation has a structure in which not only the part that will become the product but also the material injection port 5 and the material injection residue part 4 are all cured, so naturally the entire part is connected and formed. be done. Here, in order to release the molded product from the mold B, the third
As shown in the figure, in order to remove the jointed material injection residue part 4, it is pulled and the material injection port 5 connected to it is pulled.
The inner circumference of the oil seal 1 is also pulled. At this time, the acute-angled step notch 6 provided at the gate portion on the inner peripheral edge of the cavity 2 effectively works to cut off the gate portion that is being pulled and stretched, thereby separating the material injection port portion 5 and the molded product within the cavity 2. Separate parts. When this happens, the material injection residue portion 4, the material injection port 5, and the molded product in the cavity 2 are easily separated from the mold B, and when this is taken out, the oil seal 1 shown in FIG. 4 is formed. In other words, after injection molding, this structure has a mold in which the material injection port 5 is carved (see Figs. 2 and 3).
In the figure, the conventional deburring finish is performed at the same time as the mold is released from the upper mold B1), and the molded product cannot even be removed from the mold B without this separation.

Such a structure is particularly suitable for forming a small-diameter oil seal 1, and in this case, the size of the material injection port 5 required for injection can be set to a size corresponding to its inner diameter, thereby minimizing material loss. In addition, if the mold is configured as a multi-cavity mold, high productivity can be obtained, such as less material loss and advantageous finishing processability.

All of the above features are effects from a productivity perspective, and from a quality perspective, the cutter effect of the acute-angled stepped notch 6 in the gate section allows the inner periphery to be separated with high precision and uniformity, which is an improvement over conventional methods. It exhibits many properties such as preventing secondary defects such as digging in and remaining burrs during the finishing process and providing products with stable quality.

As explained above, the present invention is an ideal and revolutionary material injection mold that can greatly improve productivity and quality by releasing the molded product from the mold.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a conventional mold. Second
The figure is a sectional view showing the mold of the present invention. FIG. 3 is a partially enlarged cross-sectional view showing the state of mold release operation using the mold of the present invention. FIG. 4 is a partially cutaway perspective view showing the oil seal. A... Conventional mold, B... Material injection mold of the present invention, C... Elastic material, 1... Oil seal, 2... Cavity, 4... Material injection residue, 5
...Material injection port, 6...Step notch.

Claims (1)

[Scope of utility model registration request] In a material injection molding mold for molding an oil seal made of an elastic body, a material injection port is provided at the inner peripheral edge of the oil seal-shaped cavity of the mold on the material injection side, which is continuous from the inner peripheral edge and communicates with the material injection residue part,
The mold for material injection molding is further characterized in that an acute-angled step notch is provided in the gate portion of the inner peripheral edge.