JPH0427936B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is a molding machine that thermally melts a material resin supplied from a hopper in a cylinder and injects or extrudes the molten resin to mold the resin. The present invention also relates to a method of completely exchanging all the unchanged resin remaining inside the cylinder with the changed resin (hereinafter abbreviated as purging). [Prior Art] In recent years, in order to save labor, automate, reduce costs, etc., molding machines that are equipped with microcomputers and are program-controlled have become mainstream. For example, in a screw-in-line injection molding machine, injection speed, pressure, screw rotation speed,
There are many things that need to be controlled, such as back pressure and injection stroke, and screw-in-line injection molding machines that control all of these things through programs have already been commercialized. In this case, the operator only needs to set the molding conditions according to the type of resin, and no special skills are required. However, when molding a wide variety of products in small quantities using the same molding machine, it is often necessary to change the type or color of the resin. [Problem to be solved by the invention] However, conventionally, program control for purging has not been performed, and even during purging, molding is not performed according to the type of resin before change or the type of resin after change. Because normal molding control with set conditions was used, the resin remaining inside the cylinder was only replaced little by little, and it took a long time to completely replace it, and a large amount of material was wasted. . For this reason, there were times when operators switched to manual control and performed purging efficiently based on their experience, but this work was difficult for unskilled operators, and even experienced operators could operate multiple units at the same time. It was impossible to manipulate. [Means for solving the problem] Therefore, in the present invention, as shown in FIG. 1, a setting means 1 for specifying the resin before and after the change is provided.
, means 2 for specifying a purging operation command according to the combination of resins specified by the instruction from the setting means, and means 3 for controlling the molding machine according to the purging operation command from the specifying means. This allows purging to be completed automatically and efficiently in a short period of time. [Example] Hereinafter, an example of the present invention will be described with reference to the drawings. Referring to FIG. 2, the screw-in-line injection molding machine to which the present invention is applied includes a hopper 11 to which material resin is supplied, and a plasticizing cylinder 12 filled with material resin from this hopper 11. We are prepared. Referring to FIG. 3, on the outer periphery of the plasticizing cylinder 12 there is a band heater 13 for melting the material resin.
A screw 14 is provided inside the cylinder 12 for kneading the resin material and for injecting the molten resin from the injection port 15. Referring to FIG. 4, the screw 14 is driven by a screw drive hydraulic circuit 17 built into the frame 16, and the screw drive hydraulic circuit 17 is controlled by a control panel 18. Further, the band heater 13 is also controlled by the control panel 18. On the surface of the control panel 18, there is a mode changeover switch for switching between normal mode and purging mode.
A group of switches 19 are provided, including a setting button for specifying the type of resin and a start switch for starting the drive. The interior of the control panel 18 in FIG. 4 shows the functional blocks when the mode changeover switch is switched to the purging mode. 18a
is a resin material list in which the optimum temperature T _p (° C.) of the resin in the cylinder 12 is stored corresponding to each resin. Table 1 shows general purpose polystyrene (GPPS), polycarbonate (PC), nylon 66
An example of the optimum resin temperature T _p (° C.) of each part (injection port, front, center, and rear) in the cylinder 12 for polyacetal (PA) and polyacetal (POM) is shown.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, purging can be automatically and efficiently carried out simply by the operator making simple initial settings. In addition, the number of molding machines that can be operated by each operator has increased,
Productivity can be improved.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of the present invention, Figure 2 is a front view of a screw-in-line injection molding machine to which the present invention is applied, and Figure 3 shows details of the cylinder in Figure 2. 4 is a block diagram showing the configuration of an embodiment of the present invention, and FIG.
FIG. 3 is a waveform chart showing an example of an optimal temperature curve generated by the temperature change curve generating means 18b shown in the figure. 1...setting means, 2...defining means, 3...driving means,
11...Hopper, 12...Plasticizing cylinder, 13...
Band heater, 14... Screw, 15... Injection port,
16... Frame, 17... Screw drive hydraulic circuit,
18...Control panel, 18a...Resin material list, 18b...
Temperature change curve generating means, 18c...Temperature control unit, 18d...Purge screw movement command generating means, 19...Switch group.

Claims (1)

[Claims] 1. In the purging method of a molding machine used when changing the resin used for molding, there is a setting means for specifying the resin before and after the change, and a combination of resins specified by a command from the setting means. means for specifying a corresponding purging operation command;
A method for purging a molding machine, comprising means for controlling the molding machine according to a purging operation command from the regulating means.