JPS641060Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a heating device for an injection molding machine used to heat and fluidize a plastic material and press it into a mold for molding.

(Prior art) In general, a heating device 1A of an injection molding machine has a heating cylinder 2A heated to melt the molded resin material as shown in FIG. 6, and a band heater 30 wound around this heating cylinder. Is it heated by
Alternatively, the heating tube is heated by supplying water or oil at a predetermined temperature to the flow path through a heating zone 3A provided on the outer peripheral wall of the heating tube.

Conventionally, the heating zone 3A provided on the outer periphery of the heating tube 2A is
As shown in FIG. 5, a flow path 7A of an annular groove, a partition plate 31 that divides the flow path, and a lateral groove 32 that communicates each flow path are formed, and the flow of water or oil is as shown by arrow F. The water goes around the flow path 7A of the annular groove, hits the partition plate 31, passes through the lateral groove 32, and sequentially flows to the flow path 7A of the next annular groove.

Water or oil flowing into the heating cylinder 2A is circulated through the flow path by a temperature control device connected to the entrance and exit of the flow path via piping, and is controlled to an appropriate temperature.

(Problems to be Solved by the Invention) In such a heating device, the flow path of the heating cylinder is too long, resulting in poor responsiveness to the temperature set during injection of the molding machine, making it difficult to maintain accurate temperature control.

Moreover, simply shortening the flow path does not allow the entire heating cylinder to be kept at a uniform temperature, and the set temperature varies and the width of the temperature range increases. As a result, a problem arises in that the temperature of the heating device is incompletely controlled even if water or oil is supplied to the heating device at an appropriate temperature by the temperature control device.

Therefore, the present invention aims to stabilize control over a narrow temperature range during injection by improving the shape of the flow path of the heating cylinder.

(Means for solving the problem) In order to achieve the above object, the present invention provides a plurality of annular groove channels on the outer periphery of the heating cylinder at predetermined intervals in the axial direction of the heating cylinder. Communication passages for communicating adjacent passages are provided in an annular partition wall defining between each passage and are sequentially shifted by 180 degrees, and the fluid as a temperature medium flowing into the passage is divided into two from the communication passage and flows again. It is characterized by having heating zones that face each other in the path and merge into the next communication path.

(Function) With this structure of the present invention, the fluid flowing into the inlet of the heating cylinder is divided into two parts from the communication passage as shown in Fig. 2, and flows half a circle inside the annular groove passage. , the fluids face each other again on the flow path where the next communication path is formed, and the fluids merge into that communication path.

Therefore, the fluid sequentially branches at the outlet of each communication passage formed at an angle of 180° in the annular convex portion, and merges at the inlet, so that the passage of the annular groove is always only a half-circle passage, and no The fluid flow path formed in the tropics can be shortened. Moreover, since the flow path of the annular groove is surrounded by two branched fluids, the heating cylinder can be heated uniformly.

(Example) Embodiments of the present invention will be described based on the drawings.

As shown in FIG. 1, the heating device 1 of the present invention has a structure including a cylindrical heating tube 2 and a heating zone 3 around the outer periphery of the heating tube 2 through which hot water or hot oil passes.

The heating cylinder 2 is a part of the main body of the injection molding machine, and is used to heat and melt and move the molding material 4. A screw 5 is generally fitted into the cylinder so that it can rotate and reciprocate. The injected molding material 4 is efficiently plasticized by the transmission of shear frictional heat and external heating.

The heating zone 3 serves as a heat source for heating the heating tube 2, and may be attached as a separate structure like a band heater to the outer periphery of the heating tube 2, or it may be attached directly to the heating tube 2.
It may also be formed inside.

As shown in FIGS. 2 to 4, in the heating zone 3, a plurality of annular groove channels 7 having a predetermined width are formed on the outer peripheral wall 6 at appropriate intervals.
Further, communication passages 8, 8, etc., which communicate the adjacent passages 7, 7,... are formed parallel to the axial direction of the heating cylinder 2, having the same bottom surface as the bottom surface 7a of the passages, and the following: It communicates with the flow path 7 of the annular groove. The cross-sectional area of the communication path 8 needs to be twice the cross-sectional area of the flow path 7,
The communication path 8 has annular protrusions 9, 9 that partition each flow path 7.
The heating zone 3
A fluid 12 (water or oil) as a temperature medium flows from an inlet 10 to an outlet 11 as shown by arrow F (see FIG. 2).

To explain the function of the heating device 1 described above together with the operation of the injection molding machine, the molding material 4 supplied to the hopper 20 falls into the heating cylinder 2 due to its own weight.
The molding material 4 is fed into the tip portion 21 along the grooves of the screw 5 while being kneaded as the screw 5 rotates.

The molding material 4 in the heating cylinder 2 is heated from the outside by flowing a fluid 12 such as hot water or hot oil into the heating zone 3 around the outer periphery of the heating cylinder 2, and is also heated by frictional heat caused by the kneading action of the screw 5. As a result, heat is generated internally and the temperature rises.

While the screw 5 is rotating, its tip 21
The screw 5 is pushed back by the pressure of the semi-molten molding material 4 stored in the molding material 4, and the required injection amount is measured by defining the amount of retraction.

Next, the injection force applied to the hydraulic ram (not shown) of the injection cylinder causes the screw 5 to rapidly move forward, and the molding material 4 at its tip 21 passes from the nozzle 22 through the spool 24 in the mold 23 to the cavity 25. The resin is injected into the mold 23 at high speed, and then further heated by the mold heater 26 (for thermosetting resins) or cooled by circulating water or the like within the mold 23 (thermoplastic resins). Solidified by crab, mold 2
The molded product is taken out from step 3.

Especially in the case of thermosetting resin, the molding material 4 does not reach a completely molten state in the heating cylinder 2, but the temperature of the resin injected from the nozzle 22 is about 120 to 125°C. In other words, it is only in a semi-molten state.

This is because if the molding material 4 is heated to a temperature higher than this, the curing reaction will proceed too much and fluidity will be rapidly lost, making it impossible to completely fill the mold 23 with resin.

Therefore, it is necessary to control a narrow temperature range in order to mold thermosetting resin, and the heating device 1 having the heating zone 3 according to the present invention can maintain the required temperature using a temperature controller (not shown). A hot water or hot oil fluid 12 set at
The water flows from the outlet of one communication path 8 to the flow path 7 of the annular groove, flows into two parts, goes around the flow path 7 halfway, and faces each other again in the flow path. This facing fluid 12 joins the next communicating path 8 having a cross-sectional area twice that of the flow path 7, splits into two, and flows into the next flow path 7 of the annular groove.

In this way, the fluid 1 as a temperature medium is
2 branches the channels 7 and 8 of the heating zone 3, repeats merging, flows to the outlet 1, and circulates through the piping to the temperature control device.

Therefore, the fluid 12 does not go around the flow path 7 of the annular groove once as in the conventional case, and the fluid 12 does not go around the flow path 7 of the annular groove.
It only takes half a turn.

Therefore, the time for passing through the flow path 7 is halved, and the time for heat exchange of the temperature medium is shortened by almost half.Furthermore, since the fluid path is simple, the fluid flows smoothly without pressure loss, which improves the temperature control device. The motor load is small, and the responsiveness in setting the resin temperature of the molding material 4 is improved. Furthermore, since the fluid 12 flows uniformly through the annular groove channel 7, the molding material 4 can be maintained at a stable resin temperature within the heating cylinder 2.

(Effects of the invention) Since the present invention has the above-mentioned configuration, it is possible to shorten the flow path of the heating device and reduce the temperature inside the flow path in plastic injection molding, especially when molding thermosetting resin. Since the fluid as a medium flows evenly, it is possible to uniformly plasticize the molding material, and at the same time, the heat exchange time is significantly reduced, improving responsiveness at the set temperature and controlling the resin temperature within a narrow range. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of an injection molding machine equipped with a heating device according to an embodiment of the present invention, FIG. 2 is an enlarged front view showing the flow path of the heating device of FIG. 1, and FIG.
A cross-sectional view taken along the line A-A in the figure, Figure 4 is the 2nd
FIG. 5 is an enlarged front view showing a flow path of a conventional heating device, and FIG. 6 is a partial sectional view of a conventional injection molding machine. DESCRIPTION OF SYMBOLS 1... Heating device, 2... Heating cylinder, 3... Heating zone, 7... Annular groove flow path, 8... Communication path, 9...
Annular convex portion, 12...Fluid.

Claims (1)

[Scope of utility model registration request] A plurality of annular groove channels are provided on the outer periphery of the heating cylinder at predetermined intervals in the axial direction of the heating cylinder, and a communication path for communicating adjacent channels is provided in an annular partition wall defining between each channel. Heating zones are provided sequentially shifted by 180° so that the fluid as a temperature medium flowing into the flow path is divided into two parts from the communication path, facing each other again in the flow path, and merging into the next communication path. A heating device for an injection molding machine featuring: