JPH08300461A - Method and apparatus for producing hollow molded product - Google Patents

Abstract

PURPOSE: To easily mold a hollow molded product of which the mouth part is eccentric by simply and rapidly altering the stop position of a mold. CONSTITUTION: A mold 25 is reciprocally moved between an air blowing-in position A and a parison receiving position B through a servo motor 2 and the eccentric quantity of the mold 25 or the position where the center position of the mold 25 is stopped is inputted to the control part 8 of a hollow molding machine to which the signal of the center position of the mold 25 is inputted to alter the stop position of the mold 25 to produce a hollow molded product of which the mouth part is eccentric.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a hollow molded product, particularly a hollow molded product having an eccentric mouth.

[0002]

2. Description of the Related Art As a conventional hydraulically driven hollow molding machine, one having a structure shown in FIG. 5 is generally adopted.
That is, the resin melted by the extruder 21 passes through the crosshead 22 and is extruded downward as a cylindrical parison 23. When the parison 23 reaches a predetermined length, the mold transfer hydraulic cylinder 24 is operated to move the mold transfer device 27, to which the mold clamping device 26 having the mold 25 is attached, obliquely upward. The mold 25 in the mold open state waiting at the air blowing position A is transferred to the parison receiving position B.

Next, the mold clamping hydraulic cylinder 28 is actuated,
The parison 23 is sandwiched between the molds 25 by closing and clamping the mold clamping device 26. At the same time, by driving the parison cutting air cylinder 29 and operating the parison cutting device 30, the parison 23 is cut above the mold 25.

Next, the die transfer hydraulic cylinder 24 is operated to move the die 25 sandwiching the parison 23 diagonally downward through the die transfer device 27, so that the die 25 is blown with air again. Transferred to position A. At the air blowing position A, the blow driving hydraulic cylinder 31 is driven to drive the air blowing nozzle 33 of the air blowing device 32.
Is inserted into the upper surface of the mold 25 and air is blown into the parison 23, whereby a hollow molded product having a shape corresponding to the cavity shape of the mold 25 is molded.

The mold transfer device 27, the air blowing device 32, and the like are attached to the frame 35 of the molding machine 34. The hydraulic cylinders 24, 28, 31 are operated by the hydraulic pressure of the hydraulic unit 36.

From the air blowing position A directly below the air blowing device 32 to the parison receiving position B directly below the crosshead 22,
Alternatively, during the molding operation for transferring the mold 25 in the opposite direction, the mold transfer device 2 is arranged so that the centers of the crosshead 22 and the air blowing device 32 and the center of the mold 25 are aligned with each other.
Stoppers 38 are provided at both ends of the guide bar 37 of No. 7, and both end portions of the die transfer device 27 hit the stopper 38 by the pushing force of the die transfer hydraulic cylinder 24 and stop.

[0007]

A conventional blow molding machine is
Since it is configured as described above, there are the following problems. That is, the above hollow molding machine can easily mold a hollow molded product having a mouth at the center, but a hollow molded product in which the mouth is eccentric by an eccentric amount S as shown in FIG. In the case of manufacturing, it is necessary to stop the transfer of the mold halfway without applying the stopper to the transfer. However, if the mold is stopped midway, it does not stop at the same position each time, and variations occur. That is, when sandwiching the parison with the mold directly below the crosshead, the parison cannot be sandwiched at the same position every time. Also, when the air blowing nozzle is inserted into the upper surface of the mold directly below the air blowing device, the air blowing nozzle does not enter the hole formed on the upper surface of the mold,
Problems such as damage to the air blowing nozzle and uneven molding of the upper opening of the hollow molded product may result in molding of a defective product.

Therefore, when manufacturing a hollow molded product having an eccentric mouth, it is necessary to shift the position of the core of the air blowing device or the air blowing nozzle or change the position of the stopper. To move the position of the air blowing device,
It is necessary to change the structure of parts, re-center, and change hydraulic piping. In addition, it is necessary to change the parts in order to shift the position of the core of the air blowing nozzle.Furthermore, the core of the blow drive hydraulic cylinder and the core of the air blowing nozzle are misaligned, so bending stress occurs in the parts. There is a problem that the life is shortened. Further, regarding the change of the position of the stopper, there are problems of troublesome re-centering and setup time. Due to these various problems, it is not possible to easily change or modify the standard blow molding machine. Therefore, although it is called a special-purpose machine, the special-purpose machine is expensive and inflexible, and if the molding quantity is small, the operating rate becomes poor.

The present invention has been made in order to solve the above problems, and the stop position of the mold can be easily and quickly changed to easily form a hollow molded product having an eccentric mouth. An object of the present invention is to provide a method for manufacturing a hollow molded article and a device therefor which can be manufactured.

[0010]

According to the method for manufacturing a hollow molded article according to the present invention, the eccentricity of the mold is provided in the control section of the hollow molding machine that reciprocates the mold between the air blowing position and the parison receiving position. This is a method of manufacturing a hollow molded product having an eccentric mouth by changing the stop position of the mold by inputting the amount or the position where the center position of the mold stops.

More specifically, in the method for manufacturing a hollow molded product according to the present invention, a mold is reciprocated between a blow-in position and a parison receiving position via a servo motor, and the reciprocating mold is moved by a position detector. Change the stop position of the mold by inputting the eccentricity of the mold or the position where the center position of the mold stops to the control unit of the blow molding machine to which the signal of the center position of the mold is input. Is a method for producing an eccentric hollow molded article.

In the hollow molded product manufacturing apparatus according to the present invention, an input device for inputting an eccentricity of the mold or a position where the center position of the mold stops is connected to a position detector for detecting the center position of the mold. It has a control unit of the hollow molding machine for changing the stopping position of the mold, and a servo motor for reciprocating the mold according to a control signal from the control unit.

[0013]

Operation: Control of a hollow molding machine in which a mold is reciprocated between an air blowing position and a parison receiving position via a servo motor, and a position detector inputs a signal of the center position of the reciprocating mold. In the part, by changing the stop position of the mold by inputting the eccentricity of the mold or the position where the center position of the mold stops, even when molding a hollow molded product with an eccentric mouth, The parison can be sandwiched at the same position of the mold directly below the crosshead, and the air blowing nozzle can be accurately inserted into the hole formed on the upper surface of the mold directly below the air blowing device.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a method and apparatus for manufacturing a hollow molded article according to the present invention will be described below with reference to the drawings. In addition, the same or equivalent portions as those of the conventional example will be described using the same reference numerals. In FIG. 1 and FIG. 2, reference numeral 35 is a frame of an electrically driven hollow molding machine, and an air blowing device 32 is attached to an upper portion of the frame 35. The crosshead 22 is arranged on the left side of the air blowing device 32 in FIG. 1.
The crosshead 22 is connected to the extrusion port of the extruder 21, and the molten resin supplied from the extrusion port can be extruded downward in FIG. 1 as a cylindrical parison 23. A parison cutting device 30 is arranged immediately below the crosshead 22.

A servo motor 2 to which a rotary encoder 1 as a position detector is attached is provided below the frame 35. This servo motor 2
A ball screw 4 is rotatably connected to the via a coupling 3. The rotary encoder 1 is connected to a control unit 8 described later. A ball nut 5 is screwed into the ball screw 4. The coupling 3 is a non-backlash type, and the ball screw 4 and the ball nut 5 are high precision products having a clearance of 10 μ or less.

A connection member 6 is fixed to the ball nut 5, and a mold transfer device 27 which is movably fitted to the guide bar 7 is arranged above the connection member 6. A mold clamping device 26 for opening and closing the mold 25 is attached to the mold transfer device 27. That is, the servomotor 2 moves the mold clamping device 26 and the mold 25 between the air blowing position A shown by the solid line in FIG. 1 and the parison receiving position B shown by the phantom line in the drawing via the mold transfer device 27. It can be reciprocated.

Further, as shown in FIG. 3, a control unit 8 to which the signal 1a of the rotary encoder 1 is input is provided, and the control unit 8 has a metal corresponding to the eccentricity S of the hollow molded product. An input device 9 for inputting the eccentricity of the mold 25 or the position where the center position of the mold stops is connected.
Thus, the stop position of the mold 25 is changed, and the mold 25 is reciprocated via the servo motor (2) by the control signal 8a from this control unit. The parison emission signal 1b is input to the control unit 8.

Next, the operation of the above hollow molding machine will be described. The mold 25 stands by at the air blowing position A in a state where the mold is opened by the mold clamping device 26. Cross head 2
When the parison 23 having a predetermined length is pushed out from 2, the servo motor 2 is rotationally driven in the forward direction by the parison injection signal 1b. As a result, the ball screw 4 is rotated via the coupling 3, and the ball nut 5 meshing with the ball screw 4 converts the rotational movement into a linear movement. That is, the ball nut 5 advances to the left in the drawing, and the connecting member 6, the mold transfer device 27, the mold clamping device 26, and the mold 25, which are integrated with the ball nut 5, move to the parison receiving position B. Next, the mold clamping device 26 performs the mold clamping, and the parison cutting device 30 subsequently performs the parison 23.
Is disconnected. Next, the servomotor 1 is driven to rotate in the reverse direction, whereby the mold clamping device 26 and the mold 25 are moved to the air blowing position A. Next, the air blowing nozzle 33 of the air blowing device 32 descends and air is blown into the parison 23, whereby a hollow molded article having a predetermined shape is molded. After the cooling step, the air blowing nozzle 33 of the air blowing device 32 is raised, the mold is opened by the mold clamping device 26, the hollow molded product is taken out, and one cycle is completed.

Since the rotary encoder 1 for detecting the center position of the mold 25 is attached to the servo motor 2, the center position of the mold 25 can be always detected. Therefore, the stop position of the mold 25 can be freely changed by inputting the eccentricity of the mold or the position where the center position of the mold 25 stops to the control unit 8.

By doing so, even when molding a hollow molded product having an eccentric mouth, the parison can be sandwiched at the same position of the mold directly below the crosshead,
Further, the air blowing nozzle can be accurately inserted into the hole formed on the upper surface of the mold directly below the air blowing device.

[0021]

Since the method and apparatus for manufacturing a hollow molded article according to the present invention are configured as described above, the following effects can be obtained. (1) By inputting the eccentricity of the mold into the control unit, the position at which the mold stops can be easily and quickly changed, saving labor and shortening the setup time. (2) The position detector such as a rotary encoder provided in the servo motor constantly detects the position of the mold, so the repeat stop accuracy improves and the molding accuracy of the mouth of the molded product improves. The life of parts is extended, and molded products with the same accuracy can be obtained regardless of who molds them. (3) Positioning accuracy can be improved by using non-backlash coupling for transmitting the rotation of the servo motor and using precision products with small clearances for the ball screw and ball nut. The effect of can be further improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an apparatus for producing a hollow molded article according to the present invention, FIG. 1 (a) is a front view, and FIG. 1 (b) is a side view thereof.

FIG. 2 is a side view of FIG.

FIG. 3 is a control block diagram of a hollow molded article manufacturing apparatus according to the present invention.

4A and 4B are views showing a hollow molded product having an eccentric mouth portion, wherein FIG. 4A is a front view and FIG. 4B is a side view thereof.

FIG. 5 is a block diagram showing a conventional apparatus for manufacturing a hollow molded product.

[Explanation of symbols]

 1 rotary encoder (position detector) 1a signal 1b parison injection signal 2 servo motor 3 coupling 4 ball screw 5 ball nut 6 connecting member 7 guide bar 8 control unit 8a control signal 9 input device

Claims (3)

[Claims] 1. An eccentricity of the mold (25) to a control section (8) of a hollow molding machine for reciprocating the mold (25) between an air blowing position (A) and a parison receiving position (B). Enter the amount or the position where the center position of the mold (25) stops,
A method for producing a hollow molded article, which comprises changing the stop position of 5) to produce a hollow molded article having an eccentric mouth. 2. A mold (25) is reciprocated between an air blowing position (A) and a parison receiving position (B) via a servo motor (2), and the reciprocating motion is performed by a position detector (1). The eccentric amount of the mold (25) or the center position of the mold (25) is stopped by the controller (8) of the hollow molding machine to which the signal (1a) of the center position of the mold (25) is input. A method for producing a hollow molded article, which comprises inputting a position to change a stop position of the mold (25) to produce a hollow molded article having an eccentric mouth portion. 3. The amount of eccentricity of the mold (25) or the mold (2
An input device (9) for inputting the stop position of the center position of 5) and a position detector (1) for detecting the center position of the mold (25) are connected, and the hollow position for changing the stop position of the mold is changed. A hollow molded product having an eccentric mouth, which has a control unit (8) of a molding machine and a servomotor (2) that reciprocates a mold (25) in response to a control signal from the control unit. Manufacturing equipment.