JPH0717466Y2 - Screw cylinder for ultra high molecular weight polyethylene - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an injection molding machine for injection molding using ultrahigh molecular weight polyethylene as a raw material, and more particularly to a screw cylinder for ultrahigh molecular weight polyethylene.

(Prior Art) Ultra-high molecular weight polyethylene having an extremely high molecular weight has excellent impact resistance and cold resistance, and also has self-lubricating properties, and is therefore suitable as a material for small industrial parts.

Injection molding and extrusion molding are performed as means for forming small parts and the like with such ultra-high molecular weight polyethylene.

However, when molding using an injection molding machine, the ultra-high molecular weight polyethylene raw material is in the form of powder particles, and because the molded product itself has good sliding characteristics as used for sliding members, it is not possible to use ordinary screw cylinders. Then, there is a problem that the material slips between the cylinder and the material is not transported forward of the screw.

Since ultra-high-molecular-weight polyethylene raw materials cannot be plastic-metered by conventional conventional screw cylinders,
As disclosed in JP-A-60-250931 and JP-A-60-9723, radial grooves are provided on the inner peripheral surface of the screw cylinder supply portion to increase the forced feed force or to cool the supply zone with a cooling jacket. This is dealt with by increasing the feed force by delaying the resin melting start point in the screw cylinder and extending the length of the solid transport region by cooling with a cooling fin or a cooling fin.

(Problems to be solved by the invention) However, since the above groove machining of the screw cylinder requires additional machining to the screw cylinder made of a general material, not only the cylinder becomes expensive, but also the grooved cylinder is made into a general material. If it is used, the solid feed force will become too large, and the material will be consolidated into the screw compression zone as it is a solid, making it impossible to rotate the screw or causing resin shearing due to a sudden increase in pressure in the screw compression zone. There is a problem that it cannot be used as a general material because it generates a large amount of heat and causes resin burning. That is, the grooved cylinder becomes a special cylinder corresponding to a material having good sliding characteristics such as ultra-high molecular weight polyethylene.

In addition, when the heater heating of the screw cylinder feed section is completely stopped and cooling is performed with the cooling water jacket or cooling with fins, when molding general materials other than ultra high molecular weight polyethylene, use the cooling water jacket and cooling fins. There was the trouble that it had to be removed and replaced with normal heater heating.

Further, the cooling temperature control is unstable because the temperature is affected by the outside air temperature, the cooling water temperature, and the cooling water amount only with the fin cooling and the cooling water jacket, and it is not suitable for long-term continuous molding.

As shown in FIG. 5, the structure for such a conventional general material is the thermocouple position of the screw cylinder 12 provided in the lower part of the hopper 11, and in the figure, H3, The heater 15 provided at the position was detected by the thermocouple H3, and it was necessary to adjust ON / OFF to control the heater 15 to reach a predetermined temperature. In the figure, 13 is a screw, 14 is a nozzle part, 15 is a heater, and 16 is a cooling water jacket.

In view of this, the present invention is capable of plastic weighing not only ultrahigh molecular weight polyethylene but also general resin materials, and is capable of performing stable plastic weighing of materials with good sliding characteristics such as ultrahigh molecular weight polyethylene. The purpose of the present invention is to provide a screw cylinder for molecular weight polyethylene.

(Means for Solving the Problems) In order to achieve the above object, the present invention receives a raw material in a hopper and injects the molten raw material into a cavity of a mold from a nozzle portion at a tip by a screw rotatably provided. In the screw cylinder of the injection molding machine,
A plurality of heaters are installed between the cooling water jacket located below the hopper and each position where the thermocouple is inserted to reach the nozzle portion, and the cylinder thermocouple H3 part is placed between the heaters with the cylinder thermocouple interposed therebetween. It is characterized in that a water cooling jacket for adjusting the temperature is provided.

(Operation) When the cylinder thermocouple is set to a high temperature by the above configuration, stop the flowing water of the water cooling jacket and heat it by the heating heater. Conversely, when cooling it in the opposite direction, flow it to the water cooling jacket and set it by the heating heater. The temperature is adjusted to the temperature of.

(Embodiment) Hereinafter, the present invention will be described with reference to an embodiment shown in FIGS.

The screw cylinder for ultra high molecular weight polyethylene according to the present invention, as shown in FIG. 1, receives the raw material in the hopper 1 in the lower cylinder 2 and melts it by the screw 3 rotatably provided in the cylinder 2. In a screw cylinder of an injection molding machine in which a raw material is injected into a cavity 5 of a mold from a nozzle portion 4 at a tip, a cooling water jacket 6 located below a hopper 1 and a cylinder thermocouple (a cylinder thermocouple reaching the nozzle portion 4) A plurality of (three in the embodiment) heaters 7, 8, 9 are arranged in order from the nozzle portion 4 side between the respective insertion positions (H1, H2, H3) in the embodiment, and the heater 8 and the heater A water cooling jacket 10 for adjusting the temperature of the cylinder thermocouple H3 portion is arranged between the parts 9.

Therefore, the heater 9 is provided only near the cooling water jacket 6 of the hopper 1 from the position of the thermocouple H3, and the thermocouple 3H
The temperature is detected so that the temperature is controlled to a predetermined temperature.

A water cooling jacket 10 is arranged in the portion near the nozzle portion 4 from the thermocouple H3.

Next, the operation will be described.

As shown in FIG. 2, the cylinder 2 is a thermally continuous body,
The temperature distribution does not become discontinuous but always has a continuous temperature distribution.

For example, according to the conventional method shown in FIG. 5, each zone H1, H2, H3 of the thermocouple is set to 200 ° C., and the cooling water is flown into the cooling water jacket 16 of the hopper 11, and the cooling water at this time is set. Temperature
When the temperature is about 25 ° C, the distribution is as shown in Fig. 2.

In this state, even if the H3 part is set to 50 ° C, the temperature distribution is as shown below, and the H3 part does not fall below 130 ° C.

Next, even if the H2 part is set to 100 ° C, the temperature distribution becomes as follows, and the H2 part does not fall below 170 ° C.

If this is to be kept below the temperature distribution of Y, as shown in FIG. 3, the cooling water jacket 16 is extended in the direction of the nozzle portion 14 and provided in the conventional H3 portion, or as shown in FIG. The cooling fin 17 must be provided in the H3 part.

Therefore, when the water cooling jacket 16 is used as shown in FIG. 3, temperature distribution becomes possible as shown in FIG. 2, and when the cooling fins 17 are used as shown in FIG. Distribution is also possible, and plastic weighing of ultra high molecular weight polyethylene is possible. However, conversely, in the examples of FIGS. 3 and 4, higher temperature distribution than that of FIG. 2 is impossible, and plastic measurement of general resin materials is impossible.

In FIGS. 3 and 4, parts common to those shown in FIG. 5 are designated by the same reference numerals and description thereof is omitted.

On the other hand, Fig. 1 (present invention) shows the thermocouple positions H3 and H2.
Since the water cooling jacket 10 is provided between the parts, it is possible to lower the intermediate temperature between the H2 part and the H3 part as compared with FIG.

At this time, if the setting condition that the heater 9 is not turned on is set, the heater 9 serves as a heat radiating portion having no cooling fin, and the settings shown in FIG.

For example, if the H3 part is set to 50 ° C., the temperature distribution is adjusted as shown in FIG.

Moreover, if the water cooling jacket 6 is stopped, the water cooling jacket 6 becomes a heat radiating part, and the heating temperature of the H3 part can be adjusted by the heater 9. If H1, H2, and H3 are set to 200 ° C., the second The temperature distribution is as shown in the figure, and it is also possible to measure plasticity of ordinary general resin materials.

In this embodiment, the cooling water jacket 6 at the rear of the cylinder 2 is used.
The case where the water cooling jacket 10 is arranged between the heater 9 near the heater and the heater 8 in front of the heater has been described.
It goes without saying that the present invention is not limited to this.

(Effects of the Invention) Since the present invention is configured as described above, it is sufficient to replace part of the heater of the conventional H3 part with the water cooling jacket, and it can be manufactured at low cost. That is, if the water cooling jacket is run, the effect of cooling the feed portion as shown in FIGS. 3 and 4 can be obtained. Further, in the method of FIGS. 3 and 4, the cooling of the feed part lacks stability depending on the cooling water temperature and the outside air temperature, but when the present invention is used, the temperature of the H3 part can be adjusted to a predetermined value. Since it is controlled, stability is also good.

Furthermore, by stopping the flow of water to the water cooling jacket, it is possible to set the H3 portion to a high value, and it is also possible to easily measure the plasticity of general resin materials, so there is no need to replace the water cooling jacket or cooling fins.

That is, both ultra-high-molecular-weight polyethylene and ordinary resin materials can be plastically measured with the same screw cylinder, and can be easily remodeled, so that an excellent effect that manufacturing is inexpensive can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a screw cylinder for ultra high molecular weight polyethylene according to the present invention, and FIG.
FIG. 3 is a graph showing the relationship between each position of the thermocouple of the screw cylinder and the Cinder temperature distribution, FIGS. 3 to 5 are sectional views of a conventional screw cylinder, and FIG. 3 shows two heaters on the outer circumference of the cylinder. When the cooling water jacket is extended, the length of the cooling water jacket of FIG. 3 is reduced and cooling fins are provided between the heater and the heater of FIG.
The case where another heater is provided instead of the cooling fins in the figure is shown. 1 ... Hopper, 2 ... Cylinder (screw), 3 ...
Screw, 4 Nozzle, 5 Mold cavity, 6 Cooling water jacket, 7,8,9 Heater, 1
0 …… Water cooling jacket, H1, H2, H3 …… Cylinder thermocouple.

Claims (1)

[Scope of utility model registration request] 1. A raw material in a hopper (1) is received, and a molten raw material is injected into a cavity (5) of a mold from a nozzle portion (4) at a tip end by a rotatably provided screw (3). Cylinder for injection molding machine (2)
A plurality of thermocouples between the cooling water jacket (6) located below the hopper (1) and the nozzle portion (4).
H1, H2, H3, a plurality of heaters (7, 8, 9) and a water cooling jacket (10) are arranged, and the heater (9) closest to the cooling water jacket (6) is the cooling water jacket (6). A screw cylinder for ultra high molecular weight polyethylene, characterized in that it is sandwiched between water cooling jackets (10) and a thermocouple H3 is inserted between the water cooling jacket (10) and the heater (9).