JPH0525660B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an injection device for an injection molding machine used for molding synthetic resin.

[Prior art and issues]

Generally, the injection device of an in-line screw type injection molding machine (see FIG. 1) includes a heating cylinder 2 having an injection nozzle at its tip, and its rear end is connected to the front end of an injection cylinder 3. The inside of the heating cylinder 2 is equipped with a screw 11, and the inside of the cylinder 2 is communicated with a hopper 12 provided at the upper part of the front end of the injection cylinder 3. Also, the inside of the heating cylinder 2 is provided with a molding material on the outer periphery thereof. A heater 13 for heating and melting is attached. On the other hand, the injection cylinder 3 is provided with a cooling channel 15 for cooling the material supply path 14 communicating with the hopper 12, so that the molding material up to the screw 11 is melted due to the influence of heat transfer from the heating cylinder 2. This prevents the problem of clumping of the material and lack of smooth material supply.

By the way, since the heating cylinder 2 is heated and the injection cylinder 3 is cooled, the temperature gradient near the joint surface of both cylinders 2 and 3 becomes extremely large, and the heat of the heating cylinder 2 is taken away to the injection cylinder 3 side. Causes harm. As a result, for example, the temperature at the rear of the heating cylinder 2 becomes insufficient, and in the case of molding materials that require high-temperature molding at 300 to 400 degrees Celsius, such as ultra-engineering plastics, the amount of heat taken away becomes too large, and the temperature does not reach the desired set temperature. There was a problem that it was impossible to raise it or it took a significant amount of time.

Therefore, conventionally, in order to prevent heat radiation from the heating cylinder 2 to the injection cylinder 3, a heat insulating plate 16 (Fig. 1) was interposed between the heating cylinder 2 and the injection cylinder 3. A structure is adopted in which a required number of blind holes are provided in a portion of the holding member at the rear of the heating cylinder 2 near the opening edge to reduce the heat transfer area, but in both cases, the heating temperature in the heating cylinder 2 When the temperature reaches a high temperature, there is a problem in that a sufficient heat radiation prevention effect cannot be obtained.

An object of the present invention is to provide an injection device for an injection molding machine that solves the problems existing in the prior art.

[Means to solve the problem]

In the injection device 1 of the injection molding machine according to the present invention, when configuring the injection device formed by combining the heating cylinder 2 and the injection cylinder 3, the heating cylinder 2 and the injection cylinder The present invention is characterized in that a space 4 is provided to block heat transfer to the heating cylinder 3, and a heating means using, for example, a band heater 5 or a rod heater 6 is provided on the heating cylinder 2 side in or near the space 4. .

[Effect]

Next, the operation of the injection device 1 according to the present invention will be explained.

Heat attempting to be transferred from the heating cylinder 2 to the injection cylinder 3 is prevented by the heat insulating effect of the air layer in the space 4. On the other hand, if the temperature decreases due to heat dissipation which cannot be prevented even by the heat insulation effect, the temperature is forcibly raised by a heating means using a band heater 5 or the like to correct the temperature decrease near the joint surface of the heating cylinder 2. At the same time, the molding material is dried and preheated before the measuring process.

〔Example〕

Next, preferred embodiments of the present invention will be described in detail based on the drawings.

(First example) 1 and 2 show a first embodiment.

First, in order to clarify the present invention, a schematic configuration of the entire injection device 1 will be described.

The injection device 1 includes a heating cylinder 2 having an injection nozzle at its tip, and a held part 2 provided at its rear end.
A is formed to have a small diameter and is fitted into a cylindrical holding portion 3a provided at the front end of the injection cylinder 3. A tightening nut 17 is fixed to the front end surface of the holding part 3a via a heat insulating plate 16, and a bolt part 18 provided on the outer periphery of the heating cylinder 2 is screwed into this nut 17 to fix it. On the other hand, a screw 11 is provided inside the heating cylinder 2, and the inside of the cylinder 2 communicates with a hopper 12 provided at the upper part of the holding part 3a. Additionally, a heater 1 is provided on the outer circumference of the heating cylinder 2.
3 is attached to heat the heating cylinder 2, and the injection cylinder 3 is provided with a cooling water channel 15 for cooling the material supply path 14 communicating with the hopper 12.

Next, the main configuration will be explained.

First, the joint surface of the holding portion 3a, that is, the inner peripheral surface S1
Except for the vicinity of both ends and the vicinity of the material supply path 14, a cylindrical recess 20 as shown in FIGS. 1 and 2 is formed to provide a space 4. By selecting the shape of the recess 20, it is desirable to make the transfer area (the joint area between both cylinders) as small as possible, as long as the bonding strength is not impaired.

On the other hand, inside the held portion 2a located near the coupling surface, a plurality of rod heaters 6, which are long in the axial direction, are embedded at predetermined intervals in the circumferential direction.

With this configuration, the existence of the recess 20 blocks the heat transmitted from the heating cylinder 2 to the injection cylinder 3, and at the same time, the temperature of the held part 2a is raised by the heating of the rod heaters 6.

(Second Embodiment) Next, a second embodiment will be described with reference to FIGS. 3 to 7. In addition, FIG. 6 and FIG. 7 show a modification of the second embodiment.

The second embodiment is also basically the same as the first embodiment.

First, in the basic example shown in FIGS. 3 to 5, a recess 21 having the same shape as the recess 20 is inserted into the held part
A is formed on the outer circumferential surface S2 of a, thereby providing the space portion 4. When machining the recess 21, if circular machining is difficult, square machining may be performed as shown in FIG.

Then, the band heater 5 is installed directly using the space in the space 4 and along the space 4.
Attached.

With this configuration, in addition to obtaining the same effects as in the first embodiment, there is an advantage that the space 4 can also be used as an installation space for the band heater 5 (of course, a rod heater may also be used).

On the other hand, as shown in FIGS. 6 and 7, a concave portion 20 similar to that of the first embodiment may be provided in the holding portion 3a, and the band heater 5 may be provided in this concave portion 20. Note that FIG. 6 shows a case in which a separate sleeve 22 is used to form the material supply path 14, and in this case, the recess 20 can be formed on the entire surface of the inner circumferential surface S1 except near both ends.

Further, in the basic example shown in FIG. 3, as shown by a virtual line P, a recess 20 similar to the first embodiment may be further provided on the holding portion 3a side, and in this case,
This is effective when a sufficient air layer cannot be secured due to the presence of the band heater 5.

In addition, in other parts in FIGS. 3 to 7, the same parts as those in FIGS. 1 and 2 described above are given the same reference numerals to clarify the structure, and
Since they have the same functions, detailed explanation thereof will be omitted.

Although the embodiments have been described in detail above, the present invention is not limited to these embodiments. For example, any other heating means such as a temperature control jacket can be used as the heating means. Further, by attaching a temperature sensor to the heating means, accurate temperature control is possible by feedback control. In addition, the detailed structure, method, etc. may be arbitrarily changed without departing from the gist of the present invention.

〔Effect of the invention〕

As described above, the injection device of the injection molding machine according to the present invention is provided with a space section on the joint surface of the heating cylinder or the injection cylinder that blocks heat transfer from the heating cylinder to the injection cylinder, and a space section that blocks heat transfer from the heating cylinder to the injection cylinder. Since the heating means is provided on the heating cylinder side, the following effects can be obtained.

Since the space prevents heat from being transmitted from the heating cylinder to the injection cylinder, and the heating cylinder is actively heated by the heating means, the synergistic effect can reliably prevent a drop in temperature at the rear of the heating cylinder. As a result, even in high-temperature molding of ultra-engineering plastics, the disadvantage of insufficient temperature rise is eliminated.

Since the entire rear part of the heating cylinder can be heated,
It is possible to obtain a drying effect and a preheating effect on the molding material before melting the molding material, thereby making it possible to stabilize and ensure the measuring process.

[Brief explanation of drawings]

Fig. 1: A longitudinal cross-sectional view showing a part of an injection device according to a first embodiment of the present invention, Fig. 2: A cross-sectional view taken along line A-A in Fig. 1, Fig. 3: A second embodiment of the present invention. A vertical sectional view showing a part of the injection device according to Figure 4: B in Figure 3
5: A sectional view taken along the line C-C in FIG. D-D in Figure 6
Line sectional view. In the drawings, 1: injection device, 2: heating cylinder,
2a: held part, 3: injection cylinder, 3a: holding part, 4: space part, 5: band heater, 6...: rod heater.

Claims (1)

[Scope of Claims] 1. In an injection device of an injection molding machine in which a heating cylinder and an injection cylinder are combined, a space portion is provided on the joining surface of the heating cylinder or the injection cylinder to block heat transfer from the heating cylinder to the injection cylinder. An injection device for an injection molding machine, further comprising a heating means provided on the heating cylinder side in or near the space. 2. The injection device for an injection molding machine according to claim 1, wherein the space is a cylindrical recess formed in the peripheral surface of the joining surface of the heating cylinder or the injection cylinder. 3. The injection device for an injection molding machine according to claim 1, wherein the heating means uses a band heater provided along the space. 4. The injection device for an injection molding machine according to claim 1, wherein the heating means uses a plurality of rod heaters that are long in the axial direction of the heating cylinder.