JPH0780215B2 - Injection molding machine for clean room - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servomotor-driven injection molding machine that suppresses generation of dust from a power transmission mechanism and is compatible with a clean room.

2. Description of the Related Art Since a servomotor-driven injection molding machine does not use hydraulic fluid for drive units such as mold clamping and injection mechanisms, clean molding work without oil stains is possible, but as shown in FIG. Since the V-belt 1 and the toothed belt 4 are frequently used in the power transmission mechanism of the servo motor, fine dust is generated due to wear of these belts and pulleys, and for molding work that requires ultra-high cleanliness. Can not respond enough.

Therefore, when ultra-high cleanliness is required such as in a clean room, a large-scale dust remover must be installed near the injection molding machine to prevent dust from entering the mold operating area. Are doing

However, when such a large dust device is installed,
Not only is it expensive, but the work space is narrowed, so it is difficult to automatically eject by an ejector pin or stripper plate, such as ultra-precision parts, thin objects, or exterior parts where aesthetics are important. Work efficiency is remarkably deteriorated when the processing of (1) is manually performed.

Incidentally, FIG. 3 shows an injection drive section of a servo motor driven injection molding machine as an example.
It has a belt 1, a large V belt pulley 2 around which the belt 1 is wound, a small V belt pulley 3 and a toothed belt 4 for injection, and three toothed pulleys 5 around which the belt is wound. Although not shown, an AC servomotor for screw rotation is connected to one of the V-belt small pulleys 3, and the screw is rotated via the V-belt 1 and the V-belt large pulley 2 in the measuring cycle. An AC servomotor for injection (not shown) is connected to one of the toothed pulleys 5, and the toothed belt 4 is driven in the injection cycle to drive the ball screw mechanism 6
For example, the injection unit is moved forward or backward. Looking at the wear of the power transmission belts such as the V-belt and the toothed belt, the sliding contact points between the both side surfaces of the V-belt and the groove walls of the V-grooves of the V-pulley, and the belt of the toothed belt It occurs on the contact surface between the tooth and the pulley tooth, and when the toothed pulley has the flange 7 for preventing the belt from coming off, wear also occurs at the sliding contact portion between the side surface of the toothed belt and this rib. ing.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention An object of the present invention is a structure capable of suppressing generation of dust from a power transmission mechanism of a servomotor-driven injection molding machine.

Means for Solving Problems In an injection molding machine driven by a servo motor, a portion in contact with a toothed belt is made of a material having a high hardness and a low friction coefficient.

Action The surface of the toothed belt that comes into contact with it has a high hardness, so that its surface is less likely to wear.

Since the friction coefficient is low at the portion where the toothed belt contacts, the friction applied to the toothed belt at the time of contact and separation of the toothed belt is small, and the surface of the toothed belt is less likely to wear.

First Example First, a first example in which a resin having a high hardness and a low friction coefficient is coated on a portion in contact with a toothed belt will be described.

In FIG. 1, reference numerals 8 and 9 are pulleys with teeth made of aluminum alloy, and 10 is a timing belt. The part where the toothed belts of the pulleys 8 and 9 contact, that is, the tooth part 8a,
The surface of 9a is coated with PTFE (polytetrafluoroethylene) resin. Since PTFE has an extremely smooth surface and a low coefficient of friction, and the value of the coefficient of friction decreases as the load increases, it is suitable as a coating material for the pulley teeth where strong torque acts such as in mold clamping and injection mechanisms. In PTFE, the PV value that increases wear is generally 10 kg / c
Although the limit is m ² · cm / s, in this example, the abrasion resistance is remarkably improved by mixing the glass fibers. Since PTFE is chemically stable, it does not corrode or decompose even when exposed to the gas generated during molding and the high temperature of the heater.

A material having a high hardness and a low friction coefficient can be formed by subjecting the entire pulleys 8 and 9 to a surface treatment.

In the second embodiment, the pulleys 8 and 9 made of aluminum alloy are anodized to form a film of aluminum oxide on the surface, which is further immersed in a potassium dichromate solution at a high temperature near the boiling point after oxidation, Chromic acid is deposited in the fine pores of the oxide film to improve wear resistance.

In the third embodiment, as shown in FIG.
The tooth portions 8a and 9a of 9 are coated with PTFE in the same manner as in the first embodiment, and the flanges 11 and 12 that hold the toothed belt 10 in contact and prevent it from coming off the pulleys 8 and 9 are made of polyacetal resin. It was formed. The polyacetal resin used in this example has the smallest friction coefficient and specific wear amount among plastics, and is also excellent in chemical resistance and heat resistance.

The toothed pulley has been described above, but the same applies to the V-belt pulley.

According to each of these examples, since the toothed belt is in contact with the toothed portions 8a and 9a of the pulleys 8 and 9 with high hardness and excellent wear resistance and a low friction coefficient, when the toothed belt 10 is contacted or The friction given to the toothed belt 10 at the time of separation is small,
Both the toothed belt 10 and the pulleys 8 and 9 significantly suppress the generation of dust over a long period of time.

Further, since the flanges 11 and 12 made of the polyacetal resin adopted in the third embodiment have a small specific gravity of 1.41 to 1.425, the moment of inertia is smaller than that of the flange made of metal, and the energy loss during power transmission can be reduced.

EFFECTS OF THE INVENTION Since the generation of dust from the power transmission mechanism is significantly suppressed, the servomotor-driven injection molding machine can be used in a highly clean room without adding a special dust removing device.

[Brief description of drawings]

FIG. 1 is an external view of the first and second embodiments of the present invention, FIGS. 2 (a) and 2 (b) are external views of the same third embodiment, and FIG. 3 is a servomotor driven injection molding. It is a figure which shows an example of the injection mechanism of a machine. 1 ... V belt, 2 ... V belt large pulley, 3 ... V belt small pulley, 4,10 ... toothed belt, 5 ... toothed pulley, 6 ...
Ball screw mechanism, 8,9 ... Pulley, 8a, 9a ... Tooth, 7,
11,12… flange.

Claims (1)

[Claims] 1. In a servomotor-driven injection molding machine,
An injection molding machine compatible with clean rooms, characterized in that the part in contact with the power transmission belt is made of a material with high hardness and low friction coefficient.