JPH0664841U - Injection molding machine - Google Patents

Abstract

(57) [Summary] [Purpose] To enable the molding work of an injection molding machine to be performed early and in a stable state. [Structure] In an injection molding machine, a base 1 for mounting a mold
A heating means is mounted on the base plate, and the base is heated to the temperature during stable molding by the heating means before starting the molding. As the heating means, a plate heater 2, a bar heater 8 or the like can be used,
In the case of the plate heater 2, the bar heater 8 is provided on the side surface of the base 1.
The holes are attached to the base plate 1 by forming the holes 7.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an injection molding machine that can quickly and stably enter a molding operation in injection molding of synthetic resin.

[0002]

[Prior art]

 In injection molding, the weight of the molded product changed slightly during continuous molding, and particularly when molding precision parts, it sometimes took 500 to 1000 shots to stabilize. The main reason for this is thought to be that the temperature of the molding machine, that is, the temperature from the mold is not stable because the heat from the mold moves to the entire molding machine such as the base, cylinder, and bed. Therefore, in order to stabilize the temperature of the mold, which has a great influence on the dimensional accuracy, in an early stage, a heat insulating material is interposed between the mold and the base to stop the conduction of heat from the mold to the molding machine body. Was being done.

[0003]

[Problems to be solved by the device]

 It takes a lot of time to perform injection molding until the heat of the mold is transferred to the entire molding machine and the temperature becomes stable, and a large amount of material is wasted. Also, if a heat insulating material is interposed between the mold and the base, a small mold is likely to be affected by external conditions, environmental conditions, etc., causing molding variations and warping without using a heat insulating material. There were some positive results, and it was often difficult to prevent variations with the use of heat insulating materials.

The present invention has been made to solve the above problems, and provides an injection molding machine capable of early and stable molding by raising the temperature of a base plate to a predetermined temperature. The purpose is to

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, the injection molding machine according to the present invention is one in which a heating means is mounted on a base. As a heating means, a plate heater, a rod heater, etc. can be used. In the case of a plate heater, the rod heater is attached to the side surface of the base plate by forming a hole in the base plate.

[0006]

[Action]

 Before starting the molding, the platform is heated to the temperature at which stable molding is performed by the additional heating means, and then injection molding is performed.

[0007]

【Example】

 An embodiment of the present invention will be described with reference to FIGS. In this embodiment, a plate heater is used as a heating means, and a plate heater 2 is attached to each of four side surfaces 3 of a movable plate and a fixed plate (hereinafter referred to as a base) 1 having a rectangular plate shape. The plate heater 2 is energized to heat the base 1. 9 is a screw hole for mounting the mold.

A thermocouple 5 is attached to the back surface 4 of the base 1, and the thermocouple 5 is connected to a temperature controller 6 to control the base 1 to a set temperature.

Next, a second embodiment of the present invention will be described with reference to FIGS. 3 and 4. The same members as those shown in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. A plurality of holes 7 are formed in the base 1 in the thickness direction of the base 1 along the vicinity of the periphery thereof, and bar heaters 8 are inserted into these holes 7 as heating means.

The set temperature is determined by previously measuring the temperature of the base when the molded product is stable during continuous molding. Then, during operation, the base is managed at that temperature.

FIG. 5 is a side view of the injection molding machine, showing temperature measurement positions A to F. FIG. 6 is a graph showing the temperature change at each site, with the measurement position on the horizontal axis and the temperature on the vertical axis. The z-curve in the graph of FIG. 6 represents the temperature distribution at each measurement position during stable molding, and the x-curve represents the temperature distribution at each measurement position in the state where heating was not performed before the start of molding. The curve y represents the temperature distribution at each measurement position in the state where the bed is heated before the start of molding and raised to the temperature during stable molding according to the present invention.

In FIG. 5, A is a bed, B is a movable plate, C is a mounting plate, D is a spacer block, E is a receiving plate, and F is a template. In addition, 10 is a nozzle, 11 is a fixed board, 12 is a sprue of melted resin, and 13 is a mold part.

The area due to each measurement position and its temperature represents the amount of heat change, and the area between the curves x and y is M, and the area between the curves y and z is N. The amount of heat change required to perform stable molding without heating the base plate before conventional molding is the area (M + N), and the amount of heat change when the base plate is heated before molding according to the present invention is Only the area N results in a smaller amount of heat change than in the conventional case.

[0014]

[Effect of device]

 Since the present invention is as described above, it is possible to stabilize the mold temperature at an early stage, the number of defective products is reduced accordingly, and it is possible to produce molded products with good dimensional accuracy. Produce an effect. In addition, the platform according to the present invention has a simple structure and can be implemented by slightly modifying the conventional platform.

[Brief description of drawings]

FIG. 1 is a front view of a base plate showing an embodiment in which a plate heater is attached to the base plate as a heating unit.

FIG. 2 is a side view of the base shown in FIG.

FIG. 3 is a front view of a base plate showing an embodiment in which a bar heater is inserted into the base plate as a heating means.

FIG. 4 is a side view of the base shown in FIG.

FIG. 5 is a partial cross-sectional view showing a position where the temperature of the injection molding machine is measured.

FIG. 6 is a diagram showing changes in a measurement position and its temperature.

[Explanation of symbols]

 1 Platform 2 Plate heater 5 Thermocouple 6 Temperature controller 7 Hole 8 Bar heater

Claims (3)

[Scope of utility model registration request] 1. An injection molding machine, characterized in that a heating means is attached to a base. 2. The injection molding machine according to claim 1, wherein a plate heater is mounted on a side surface of the base as a heating means. 3. The injection molding machine according to claim 1, wherein a hole is formed in the base, and a bar heater is inserted into the hole as a heating means.