JPH05436A - Injection molding machine - Google Patents

Abstract

PURPOSE:To provide an injection molding machine equipped with a resin flow path having excellent bite and fluidity of resin in the injection part, besides, having high corrosion-resistance and abrasion-resistance. CONSTITUTION:In an injection part, there is formed a dimple by shot-peening or the like on the surface (e.g. the inner surface of a screw fitting hole 17, outer surface of a metering screw 11) of a material for forming a resin flow path.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection section of an injection molding machine.

[0002]

2. Description of the Related Art An injection molding machine has an injection section and a mold clamping section, and a molten resin is injected from the injection section into a mold which has been clamped to mold the resin. At this time, for example, in the in-line type injection unit,
The measuring screw melts and injects the resin.
That is, by driving and rotating the measuring screw arranged in the barrel, the resin pellets are taken in from the hopper, and while being compressed, they are kneaded in the flight (spiral ridge), and by the frictional heat at that time and the heat supplied from the outside. Melt the resin. The molten resin is stored in the front resin reservoir, and then the measuring screw itself is extruded forward, so that the molten resin is injected all at once into the mold through the injection nozzle attached to the barrel tip.

As described above, the injection part of the injection molding machine has a resin flow path from the resin supply part (hopper) to the injection nozzle, and the surface of the member forming this flow path (for example, the outer surface of the measuring screw described above). And the inner surface of the barrel) come into intimate contact with the resin, the physical wear of the flow path surface is large in the molding of resin mixed with a high hardness reinforcement such as glass fiber.
In addition, the surface of the flow channel may be chemically corroded by the decomposition gas of the resin generated when the resin is melted.

For this reason, conventionally, the surface of the resin flow path in the injection portion is subjected to chrome plating treatment, titanium nitride treatment or heat treatment, or a special alloy material is used to physically and chemically prevent corrosion and wear. It is considered expensive. Also,
The surface of the resin flow path is polished to have a smoothness as high as possible.

On the other hand, although the smoothness is high, the so-called bite in which the metering screw takes in and transports the resin at the resin supply port may become poor, or slippage may occur during kneading and the metering process may become unsuccessful. Conversely, if the resin has a high viscosity and is well compatible with the surface of the resin flow path forming member, it tends to adsorb to the surface of the flow path, and the entire resin does not flow uniformly and stays in part. May occur and cause so-called burning or deterioration of the resin, and the quality of the molded product may deteriorate.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an injection molding machine provided with a flow path surface which is resistant to physical wear and chemical corrosion and has good resin flowability.

[0007]

Means for Solving the Problems Dimple processing is performed by shot peening or the like on the surface of a resin flow path in an injection portion.

[0008]

The dimples on the surface of the flow channel make it possible to favorably penetrate into the resin and prevent adsorption to the surface of the flow channel. Also,
The dimples formed by shot peening improve physical and chemical properties with respect to wear and corrosion of the surface of the flow path.

[0009]

EXAMPLE FIG. 2 shows an injection section 1 of an injection molding machine. The other parts of the mold clamping unit and the injection molding machine, which are opposed to the mold clamping unit, are the same as in the related art and will not be described. The injection unit 1 is provided with a front plate 3 and a rear plate 4 which are fixed to the extruder base 2 and are erected parallel to each other. The pusher plate 6 slides forward and backward on a horizontal tie rod 5 that connects the plates 3 and 4. It is mounted so that it can move freely. A hopper 7 and a cylinder assembly 8 are mounted on the front plate 3. The cylinder assembly 8 is mainly composed of a barrel 9, a nozzle 10 at its tip, and a measuring screw 11 fitted inside the barrel 9. Reference numeral 12 is a band heater, reference numeral 13
Is a nozzle adapter, and reference numeral 14 is a barrel adapter.

The barrel 9 is fixed to the front plate 3 by the rear portion penetrating the stay portion 15 of the front plate 3 and the front plate 3 and the barrel nut 16 being screwed to the rear end portion. The barrel 9 has a screw mounting hole 17 penetrating in the axial direction, and the measuring screw 11 is inserted into the mounting hole 17. The rear end of the measuring screw 11 extends rearward from the rear end of the barrel 9, is pivotally supported by a spline bush 18 pivotally supported on the front surface of the pusher plate 6, and is prevented from coming off by a screw retainer 19. There is. The hopper 7 communicates with the screw mounting hole 17 through a resin supply port 20 formed in the stay portion 15 of the front plate 3.

It should be noted that a flight (spiral ridge) 21 is formed between the position of the resin supply port 20 and the tip end of the measuring screw 11 in a mounted state, at a pitch matching the supply zone, the compression zone and the measuring zone. (FIG. 1), and the screw tip 22 is attached to the tip. The screw tip 22 includes a seat slider 23 and a valve slider 24.

That is, in the injection section 1, from the hopper 7 to the nozzle hole, between the resin supply port 20, the inner surface of the screw mounting hole 17 and the outer surface of the measuring screw 11, the nozzle 10, the barrel adapter 14 and the valve slider 24. A series of resin flow paths are formed between the inner surface and the outer surfaces of the screw tip 22 and the seat slider 23. In this embodiment, the surface of the member desired for this resin flow path, that is, the inner surface of the screw mounting hole 17, the nozzle 10, the barrel adapter 14, and the valve slider 24.
Fine dimples 25 (FIG. 3) are uniformly formed by shot peening on the inner surface of, the outer surface of the measuring screw 11, the screw tip 24, and the sheet slider 23. In FIG. 1, the dimples 25 are indicated by dots only at the portions indicated by (B) in order to avoid making the figure complicated, but the dimples 25 are also indicated at the portions described at (A) at the positions described above. Exists on one side.

In the case of shot peening, the size of the dimple 25 depends on the size and strength of the steel ball to be collided, but in the embodiment, a steel ball of φ50 to 80 μ is used and the depth is 20.
The dimples 25 have a size of about μ.

The dimples 25 are not provided uniformly on the entire surface of the resin flow path, but may be provided partially at a particularly required place, for example, on the inner surface of the screw mounting hole 17 or the front surface of the flight 21 of the measuring screw 11. Alternatively, such a place may be provided with high density and focus. Further, the dimples 25 can be formed by rolling or chemical means.

The function of the injection part 1 in the injection molding machine is the same as the conventional one. When the injection command is issued after completion of the mold clamping, the pusher plate 6 is pushed forward, and the measuring screw 11 is advanced in the barrel 9 together with it. Then, the already measured molten resin is injected. Then, after holding pressure and cooling, the measuring screw 11 is driven and rotated on the injection part side during cooling while the mold is opened, the product is taken out, and the mold is re-clamped on the mold clamping side, and the meter moves backward while controlling the back pressure. Then, the resin is weighed and melted.

During this time, the resin pellets in the hopper 7 are taken in from the supply port 20 by the action of the flight 21 in the measuring screw 11 and sequentially sent forward through the resin flow path in the injection section 1 to be kneaded and melted. Since the dimples 25 are applied to the surface of the resin as described above, the flow of the resin is smooth, and burning or deterioration due to retention does not occur. This is because, as shown in FIG. 3, in the concave portion of the dimple 25 provided on the surface of the resin flow path, the resin flows in a circular shape in the traveling direction, and innumerable minute balls intervene on the surface of the resin flow path. The mainstream resin moves smoothly, and the resin fitted in the concave portion of the dimple 25 rolls as shown by the broken line in FIG.
It is thought that it is because they go outside and join the mainstream, and they are constantly replaced. Note that FIG. 3 shows a resin flow path between the barrel 9 and the measuring screw 11.

The surface of the resin flow path is formed by dimples 25 so as to have an appropriate rough surface.
No useless slippage occurs between 1 and the resin, and the functions of kneading and resin melting are sufficiently exerted. Particularly in the vicinity of the resin supply port, the bite into the resin pellet which has not been sufficiently melted becomes good.

Further, when the dimples 25 are made by a method having a densification and homogenizing action on the surface of the member such as shot peening or rolling, the surface of the member is hardened so as to have abrasion resistance and chemical corrosion resistance. Is improved. In addition, since the layer in which the compressive stress remains on the surface increases the fatigue strength of the material, the fatigue fracture that tends to occur with a small diameter measuring screw is reduced.

[0019]

EFFECTS OF THE INVENTION The resin bite and flow in the injection section are good, accurate measurement and high quality molten resin are obtained.
Good quality molded products can be produced.

[Brief description of drawings]

FIG. 1 is a front view of a main part shown in cross section.

FIG. 2 is a front view of the injection unit shown in cross section.

FIG. 3 is an enlarged cross-sectional view of a main part.

[Explanation of symbols]

1 Injection Section 9 Barrel 10 Nozzle 11 Measuring Screw 17 Screw Mounting Hole 20 Resin Supply Port 21 Flight 22 Screw Tip 23 Seat Slider 24 Valve Slider 25 Dimple

Claims (2)

[Claims] 1. An injection molding machine comprising an injection part and a mold clamping part, wherein a resin flow path in the injection part is subjected to dimple processing. 2. The injection molding machine according to claim 1, wherein the dimple processing is performed by shot peening.