JPS6078712A - Mold - Google Patents

Abstract

PURPOSE:To prevent flashes securely from occurring on a molded piece by detecting the parting surface pressure with the surface pressure detecting device fitted on the parting surace of a mold controlling injection pressure etc. so that the parting surface pressure does not become negative. CONSTITUTION:A rod 6 is set to the hole 2b provided in the fixed retainer plate 2 of the mold composed of fixed adapter plate 1, fixed retainer plate 2, movable retainer plate 3, the movable adapter plate 4, etc., strain gages 7, 8 are set to the rod 6 and the backup plate 9 is put on the end 6p of the rod 6 to comprise the parting surface pressure detecting device. Molten resin is injected from an injection molding machine through the resin inlet port 2a into the cavity 5 for molding. In that case, the quantity of strain of the rod 6 is measured by the strain gages 7, 8, the surface pressure between the parting surfaces 2p, 3p is detected and molding is conducted by controlling injection pressure etc. so that the parting surface pressure does not become negative.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold that can be applied to injection molding machines, Guicast machines, double-acting presses, and the like.

An example of a conventional injection mold is shown in FIG. In FIG. 1, I is a fixed side mounting plate, 22 is a fixed side template, 23 is a movable side template, 4 is a movable side mounting plate, 5 is a molded product cavity,
22a is the resin inlet, 22p is the fixed side parting surface, 2
3p is a movable parting surface.

Molten resin injected from the injection molding m, (not shown) flows through the resin inlet 22.11 and fills the molded article cavity 5. If the pressure of the filled molten resin becomes too high, the mold opening force as a result of the cavity internal pressure overcomes the mold clamping force of the injection molding machine and opens the mold. When this happens, the molten resin flows out into the gap between the parting surfaces 22p and 23p, causing cracks in the molded product. In order to prevent this from happening, it is necessary to prevent the mold from opening due to the internal pressure of the cavity, but with conventional methods it is not possible to reliably detect the state before the mold opens, so the injection speed and injection pressure must be appropriately estimated. There was no way to control it. In other words, there was no reliable means of preventing Paris.

The present invention provides a mold having a device for detecting parting surface pressure as a means of grasping the state immediately before the occurrence of flaking, in order to reliably prevent the occurrence of flaking, which could not be prevented by the conventional method. By detecting the parting surface pressure, the injection side fill is devised so that the parting surface pressure does not become negative, thereby reliably preventing °ζ burrs.

The present invention will be explained below with reference to embodiments shown in the drawings. An embodiment of the present invention is shown in FIG. 2. A parting surface pressure detection device is incorporated in the A part of FIG. 2, and the details of the A part are shown in FIG. is shown in Figure 4. In Figure 2,
1 is the fixed side mounting plate, 2 is the fixed side template, 3 is the movable side template,
4 is the number of movable cases (=J plate, 5 is the molded product cavity, and 2a is the resin inlet.

Next, in Figures 3 and 4, the fixed side template 2 has holes 2b.
is opened, and the rod 6 connects its small end 6a to the template 2.
It is fixed and installed.

Reference numeral 7.8 denotes a strain gauge, which is attached to the rod 6, and its Riet wires 7a and 8a are connected to a2 of the fixed side template 2.
It is led to the outside through C.

On the other hand, 9 is a receiving plate, and its load surface 9b is the tip 6 of the rod 6.
It comes into contact with p. 10 wedge pieces, 11
1 is a fixing bolt, 12 is a plate attached to the movable side template, 1
3 is a push bolt that is screwed through the plate 12. and receiving plate, wedge piece and fixing bolt 9.10.
11 is incorporated into a groove 3a provided in the movable template 3. Further, 2p and 3p are parting surfaces of the stationary template 2 and the movable template 3, respectively.

Next, the operation will be described. The injection filling operation into the mold cavity 5 is similar to that of the conventional example. Further, although the rod 6 is fixed to the stationary mold plate 2, the receiver plate 9 can be finely adjusted by means of a wedge piece lO. Immediately, wedge piece I
By pushing O downward in FIG. 3 with the push bolt 13, the plate 9 of the receiver can be strongly pressed against the rod 6. The contact pressure between the two is determined by strain gauge 7.
8 is detected as the amount of distortion of the rod 6.

First, when the mold is closed with zero (or slight) mold clamping force, the surface pressure between the parting surfaces 2p and 3p is also @ (or slight). At this time, the wedge piece 10 is pushed in and finely adjusted so that the surface pressure between the rod 6 and the receiving plate 90 is greater than zero. This state is the breaking point in preventing the occurrence of firmness.

When the mold clamping force of the mold increases due to the mold clamping force of the injection molding machine, the parting surfaces 2p and 3p and the rod tip 6p
, the surface pressure between the load surfaces 9p also increases.

When the mold clamping force becomes sufficiently large, molten resin is injected and filled into the molded product cavity 5 from the resin inlet 2a.

Then, the mold opening force due to the resin pressure in the cavity increases, and the surface pressure between the parting surfaces 2p and 3p, the rod tip 6p, and the load surface 9p decreases accordingly. If the surface pressure does not become zero during the injection process, the parting surface will not open and no paris will occur.

In this embodiment, two 7.8 strain gauges are used, but these are rounded to compensate for the influence of bending of the rod 6, and if the rod 6 does not bend, only one strain gauge may be used. However, if you want to be a little more accurate, you can consider using three or more.

Fig. 5 is another embodiment different from Fig. 3, and shows another example in which a parting surface pressure detection device is incorporated. Any pressure detection sensor may be used. Figure 5 shows pressure detection sensor 1 using piezoelectric effect.
In this example, one end of the sensor 14 is fixed to the hole 2b of the stationary mold plate, and the other end of the sensor 14 is brought into contact with the plate 9 in which the mold is closed. Further, 14a is a lead wire of a pressure detection sensor. However, this embodiment is also similar to the above-mentioned embodiments in terms of operation and effect.

Since the present invention is configured as explained in detail above,
Changes similar to changes in surface pressure between the parting surfaces of a mold can be detected. As a result, it is possible to understand the changes in the parting surface pressure during the 1=J exit process, and when the surface pressure disappears, a gap is created between the parting surfaces, causing firmness in the molding, so it is possible to monitor the occurrence of flash. Therefore, it can be used to prevent the occurrence of firmness.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a conventional mold, FIG. 2 is a side sectional view of a mold showing an embodiment of the present invention, FIG. 3 is a detailed view of section A in FIG. 2, and FIG. FIG. 5 is a cross-sectional view of essential parts showing an embodiment of the present invention that is different from FIG. 3. Description of main parts of the figure 2 - Fixed side template 2a - Resin inlet 2b - Hole 2c - Groove 2p, 3p - Parting surface 3 - Movable side template 3a - Groove 5 - Molded product cavity 6 - Rondo 6a - Small end Part [3p-11 Rondo tip 7.8- Strain gauge 9 - Receiving plate 9p - Load surface 10 - < Rust piece 11 - Fixing bolt 12 - Plate Fig. 3 Do Fig. 5

Claims (1)

[Claims] A mold characterized by incorporating a surface pressure detection device into the parting surface of the mold.