JPS6412207B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a mold release method for thermosetting resin or thermoplastic resin molded articles.

Conventionally, molded products such as bowls and cups that have a reverse tapered part on a part of the bottom, commonly known as an undercut, have been manufactured using split molds.

However, when manufactured using split molds, burrs were formed at the joints of the molds, which required work to be removed.

The above-mentioned deburring is done manually, which is not only very troublesome but also inefficient, and this type of molded product has the problem of being seen as having low value.

Furthermore, split molds were expensive because they were difficult to manufacture, and the cost of manufacturing the molds had a large effect on the quality of the product.

Therefore, in order to eliminate the above-mentioned drawbacks, compression molding, sometimes injection molding, etc. is carried out using a cutting die, and after the molding is completed, the bottom of the molded product is pushed with a push rod or the like to release it from the cutting die. I'm getting older (Jitsukai No. 50-94274).

However, although this method can produce a molded product without burrs, it is likely to cause damage or deformation of the bottom of the molded product because the uncured molded product is pushed with a dowel to forcefully release the molded product immediately after molding. There were problems such as the push marks left by the push rod.

Therefore, the inventor proposed Japanese Patent Application No. 52-80064 (see Japanese Patent Publication No. 57-50651) in order to eliminate these drawbacks.

Although the invention was able to solve all of the above-mentioned drawbacks, it was found that the ring-shaped elastic material provided between the cutting die and the surface plate was easily damaged.

This invention prevents the molded product from being damaged, deformed, or leaving traces of the punching rod when producing a molded product with a reverse taper such as a bowl or cup. In addition, the present invention provides a mold release method that can be efficiently used, does not require a ring-shaped elastic material, and can be operated continuously without the need to replace the elastic material.

Hereinafter, one embodiment will be described in detail with reference to the drawings. Reference numeral 1 indicates a bowl as an example, and reference numeral 2 indicates a bottom leg of a reversely tapered molded product.

This type of molded product is compression molded, or sometimes injection molded, using a mold 3 as shown in FIG.

That is, the mold 3 is composed of a cutting die 4, upper and lower dies 5, 6, and a surface plate 7.

A protrusion 8 is provided at the center of the lower end of the cutting die 4, a recess 9 corresponding to the protrusion is provided above the center of the surface plate 7, and a doughnut-shaped gap is provided between the protrusion 8 and the recess 9. 10 are formed.

Further, the surface plate is provided with a compressed air inlet hole 11, and the tip of the compressed air inlet hole is located in the gap 10 between the surface of the surface plate 7 and the lower surface of the protrusion 8 of the cutting die 4 and the lower die 6. It's open.

12 is a cavity provided in the mold 3, 13 is a locking tool for fixing the cutting die 4 to the surface plate 7, and 14 is a horizontal groove in which the tip of the locking tool 13 installed around the lower part of the cutting die 4 engages. be.

To produce a molded product using the mold 3 described above, an appropriate amount of thermosetting resin or thermoplastic resin is poured into the cavity 12 of the cutting mold 4 and the lower mold 6 mounted on the surface plate 7. The mold 5 is set and in this state is heated and pressurized at the same time.

At this time, as shown in FIG. 2, the entire cutting die 4 is pressed downward, the tip of the locking tool 13 comes into close contact with the upper side of the lateral groove 14 of the cutting die 4, and the gap 10 becomes sealed.

Immediately after the molding is completed, the pressing state is released, the upper die 5 is released from the cutting die 4 and the lower die 6, and then compressed air is forced into the compressed air inlet hole 11 provided in the surface plate 7.

Then, compressed air is supplied to the surface of the surface plate 7, the lower surface of the cutting die 4, and the gap 10 of the lower die 6, and the pressure of the compressed air pushes the cutting die 4 until the lower side of the lateral groove 14 comes into close contact with the tip of the locking tool 13. is pushed up (see Figure 4).

At that time, as is clear from the drawing, the cutting die 4 and the lower die 6
The joint surface of the mold for forming the bottom leg of the reversely tapered bowl separates, and a gap 15 is formed there.

Therefore, the compressed air that pushed up the cutting die 4 passes through the gap 15 and fills the space between the lower die 6 and the bottom of the bowl.
Gradually press down on the bottom of the bowl.

At this time, the outer peripheral surface of the bottom leg 2 of the bowl is locked to the molded corner of the bottom leg of the cutting die 4, but this is because the bowl is in an uncured state and there is a gap 15 between the cutting die 4 and the lower die 6. was formed, so when the bottom of the bowl is pressed with compressed air, the lower end of the bottom of the bowl easily escapes toward the gap 15, and not only is the mold release performed smoothly,
Since no unreasonable force is applied to the bowl, there is no possibility of deformation or the like.

The mold release method of the present invention is as described above, and according to this method, a molded product having an inversely tapered bottom leg, such as a bowl or a cup, can be molded easily and smoothly using compressed air. There is no damage or deformation on the bottom of the molded product, and no traces from the pins.

Furthermore, since a ring-shaped elastic member is not required, there is no need to interrupt operation to replace the elastic member, and continuous operation is possible.

Note that molding can be carried out efficiently if the supply of compressed air is linked to the molding operation using a timer.

Further, although the above embodiments have been explained about bowls and cups, mechanical parts having reversely tapered portions can also be molded in the same manner.

[Brief explanation of drawings]

Figure 1 is a perspective view showing a bowl as an example of a molded product, Figure 2 is a longitudinal sectional view of the central part of the mold, Figure 3 is a plan view of the same, and Figure 4 is a collapsed central part showing the state at the time of mold release. FIG. 1... Molded product, 2... Bottom leg of the molded product, 3...
Mold, 4... Cutting die, 5... Upper die, 6... Lower die, 7
... Surface plate, 8 ... Projection, 9 ... Recess, 10 ... Gap, 11 ... Compressed air inlet, 12 ... Cavity, 13 ... Locking tool, 14 ... Horizontal groove, 15 ... gap.

Claims (1)

[Claims] 1 A mold 3 for molding a synthetic resin molded product 1 having an inverted tapered bottom leg 2 includes a cutting mold 4, an upper and lower mold 5,
6 and a surface plate 7, a protrusion 8 is provided below the cutting die, a recess 9 corresponding to the protrusion is formed on the surface plate 7, and a donut-shaped gap 10 is formed between the two. Also, a compressed air inlet hole 11 that opens into the gap is provided in the surface plate 7, and immediately after molding, the upper die 5 is removed and compressed air is forced into the gap, and the pressing force of the compressed air slightly removes the cutting die 4. The molded product is raised upward, and the cutting mold 4 and the lower mold 6 are moved to create a gap 15 between the molded parts of the bottom leg, and the uncured bottom leg of the molded product escapes into this gap, allowing smooth mold release. A method for releasing a synthetic resin molded product, characterized by: