JPS6039008B2 - Thermoplastic resin hot runner mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold for injection molding of thermoplastic resin, and more particularly to a hot runner mold for multi-cavity molding for four-mold molding, which is easy to manufacture.

Hot runner technology in injection molding is attracting attention as a rational molding method because unnecessary parts such as sprue runners are not generated during molding.

There are various methods of hot runner technology, but the linear mold method shown in Figures 1 and 2 is particularly effective as a hot runner mold technology that can mold a large number of small molded products with a high runner ratio and is highly effective. A side gate type hot runner mold using a hot block has been proposed.

As shown in FIGS. 1 and 2, this technique consists of an elongated hot block kept at a high temperature and cavity blocks 4 provided on both sides adjacent to the hot block.

The hot block is supplied with molten resin from a sprue 8, and is connected to a main runner 2 provided in the center of the hot block 1 and sub-runners 9 on both sides of the main runner 2. A gate 3 on the hot block side is provided.

The gate 3 is connected to the hot block 1 and the cavity block 4.
It opens at the adjacent surface 10 of . Therefore, the hot block 1 has the function of supplying the molten resin received from the sprue 8 to a large number of gates 3 provided on both adjacent surfaces 10. On the other hand, the cavity block 4 provided on both sides of the hot block 1 via the adjacent surface 10 has a cavity 6 corresponding to the gate 3 on the hot block side. have. In the closed mold state, the gate 3 on the hot block side and the gate 5 on the cavity side are connected, allowing molten resin to flow into the cavity 6. On the other hand, in the case of the connection shown in the right half of Fig. 2, the gates of the cavity block 4 and the hot block are cut, and the gate 3 on the hot block side is closed by the adjacent surface 10a to prevent the molten resin in the hot block from flowing out. become.

Z In such a mold, the molten resin reliably flows into the cavity, and the resin in the cavity is cooled and solidified to become a product. Furthermore, the gate is reliably cut by the mold opening operation, and the product can be taken out. The three most important things in such a mold are that the hot block 1 and the cavity block 4 can slide reliably when opening and closing the mold, that the molten resin does not leak, and that heat insulation is achieved.

In other words, if the contact area between the hot block 1 and the cavity block 4 is large, the insulation between them will deteriorate, making it difficult to maintain each at a predetermined temperature. For this reason slide 10
It is not possible to increase the contact area of In order to seal the molten resin in a limited area and ensure smooth sliding, it is necessary to maintain the distance between the hot block 1 and the cavity block 4 with extremely high dimensional accuracy. The present invention was invented in view of the above-mentioned points, and the two cavity blocks provided adjacent to each other on both sides of the hot block are fixed to each other via a connection part, and the temperature is applied to this connection part. By providing a means for adjusting the temperature of the joint and changing the temperature of the joint, the joint is thermally deformed, thereby changing the relative position of both cavity blocks, thereby reducing the gap between the hot block and the cavity block. It is an object of the present invention to provide a hot runner mold that can greatly reduce the burden of mold manufacturing and adjustment. The present invention will be specifically described below based on the drawings.

The inventors conducted various studies on adjusting the distance between the hot block and the cavity block, and as a result, in an actual mold, the middle W of the hot block 1 is fixed as shown in FIG. It has been found that the gap between the sliding surfaces 10 can be conveniently adjusted by adjusting the length of the connecting portion in the direction of arrow A.

Possible means for this include the use of wedges or screws, but such mechanical methods are difficult to adjust and tend to go awry during use, which poses practical problems.

As a result of various studies on this point, we fixed the cavity block portion 4 and the connecting portion 12 mechanically, changed the temperature of the connecting portion 12,
By causing thermal deformation, the relative distance between the hot block 1 and the cavity block portion 4 could be changed quite precisely. This method is extremely advantageous because the dimensions can be stably maintained as long as the temperature is adjusted accurately. The temperature can be adjusted by using a heater, water, oil, or other hot soot that is very commonly used in ordinary injection molding machines. That is, as shown in FIG. 3, a common method is to provide a large number of temperature control holes 13 in the connecting portion 12 to allow hot soot to flow therein or to insert a heater therein.

The connecting portion does not need to be placed all the way through, and may have a simple structure in which the connecting portion 12 is pipe-shaped and the heater 14 is mounted inside, as shown in FIGS. 4 and 5. 1
5 indicates the lead wire of the heater.

The form of thermal deformation differs depending on the arrangement method of the temperature control means provided in the lotus part and the temperature control conditions, but the temperature distribution in the direction perpendicular to the parting surface is made uniform or symmetrical, and the arrows in Figs. 3 and 4 It is common to move the positions of both cavities in parallel, as shown in A.

Another practical form of thermal deformation is bending deformation such that the parting surface 11b side of the movable cavity plate 4b of the cavity block 4 becomes convex as shown in FIGS. 6-8. Such deformation can be easily achieved by asymmetrically controlling the temperature of the connecting portion 12. For example, in FIG. 6, if high temperature hot soot is passed through the upper salt adjustment hole 13a and a relatively low temperature heating medium is passed through the lower temperature adjustment hole 13b, arrow B in FIG.
Bending deformation can occur. The characteristic of bending deformation is that the parting lithography 1 is caused by slight deformation of the connecting part 12.
This is the point where a large deformation in 1b is obtained. The bending deformation method brings about many other effects.

FIG. 8 shows that the method of bending and deforming the cavity block brings about many other effects. FIG. 8 shows an enlarged view of the open state of the mold in which the cavity block is undergoing bending deformation, and it can be clearly seen that the cavity flock 4 is far away from the hot block. In the one shown in FIG. 8, temperature control holes 13a and 13b are also provided at the connecting portion of the stationary cavity block. In this state, there is almost no contact between the hot block 1 and the cavity block 4, the sliding surface is easy to operate, no wear occurs, and heat loss is extremely small. In addition, since the mold closing pressure of an injection molding machine is generally extremely high, ranging from several tons to several thousand tons, it is possible to counter the thermal distortion of the cavity block according to the present invention as described above and realize normal mold closing. . Of course, it is practically effective to reduce the stress required for deformation and the burden on the mold closing mechanism by reducing the thickness of the connecting portion between the cavity blocks. That is, the bending of the connecting portion is adjusted, the gap between the hot block and the cavity block is reduced, and normal molding can be performed. As explained in detail above, by carrying out the present invention, it is extremely easy to adjust the gap between the hot block and cavity block, which is a major problem in side gate type hot runners, and the burden of mold manufacturing and adjustment can be greatly reduced. There is a characteristic that.

[Brief explanation of the drawing]

Figures 1 and 2 show a side gate type multi-cavity hot runner mold with a general linear hot block, Figure 1 shows a cross section at the parting line, and Figure 2 shows a cross section at the parting line. is a sectional view taken along a plane including the gate. 3 to 8 are diagrams showing embodiments of the present invention, and FIG. 3 is a sectional view of the mold of the present invention in a plane including the gate. Fourth
The figure is a perspective view showing another embodiment, showing the cavity block and the connecting part. FIG. 5 shows the details of the connecting portion shown in FIG. 4, and shows a cross section of the connecting portion. FIG. 6 is a diagram showing still another embodiment, showing the side surface of the cavity block and the connecting portion. FIG. 7 is a diagram illustrating a state in which the cavity block and the connecting portion shown in FIG. 6 are temperature-controlled and thermally deformed, and shows a lateral side. FIG. 8 shows an example in which the cavity block and the connecting portion shown in FIGS. 6 and 7 are assembled into a mold, and is also a side view of the mold. 1
...hot block, 2...main runner, 3...gate on hot block side, 4...cavity block, 5...gate on cavity side, 6...cavity, 12...connection, 13, 13a, 13b temperature control hole , 14... Heater. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Scope of Claims] 1. A hot block having a linear runner through which molten resin flows, a plurality of gates provided perpendicularly to the runner or at an angle close to the runner, and a cavity corresponding to the gate; In a hot runner mold consisting of cavity blocks provided adjacent to both sides of the hot block, the cavity blocks provided adjacent to both sides of the hot block are fixed to each other via a connection portion, and the connection portion A means for adjusting the temperature is provided in the part,
By changing the temperature of the connection part, the part is thermally deformed,
A thermoplastic resin hot runner mold that allows the relative positions of the two cavity blocks to be changed. 2. In Claim 1, the temperature regulating means installed at the connecting portion comprises means for thermally deforming the connecting portion so that the distance between the cavity blocks provided on both sides of the hot block changes in parallel. Hot runner mold. 3. According to claim 1, the temperature adjusting means provided at the connecting portion is capable of vertically asymmetrically changing the temperature of the connecting portion such that the parting surfaces of both cavity blocks are bent into a convex shape and deformed. Hot runner mold consisting of means.