JP3515062B2 - Multi-layer molded product molding equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for molding a molded article having a plurality of layers, and in particular, a medical tube for which the shape, size, hardness, etc. must be changed within a certain length range. It is effective when molding.

[0002]

2. Description of the Related Art A medical tube for attaching a fine camera or lighting equipment to the esophagus or a passage from the anus to the internal organs has various sizes and shapes, depending on the size of the patient and the portion through which the tube is inserted. Flexibility is required. Therefore, tube manufacturers must manufacture high-precision tubes that meet the requirements by covering multiple cores with synthetic resin layers, rubber layers, etc., based on the instructions ordered from the hospital. I won't. Conventionally, a plurality of extruders having a screw built into a cylinder are connected to a molding header, and in the process in which a core tube passes through the header, the raw materials are discharged from each extruder and the outer peripheral surface of the tube is filled with raw materials. A plurality of coating layers are formed.

[0003]

In this case, it is the extruder that sets the shape, hardness, size and flexibility of the plurality of coating layers, and the driving mode of the extruder is a computer that drives the motor that rotates the screw. The amount of protrusion of the raw material is adjusted with high accuracy while controlling. However, even if the rotation of the motor is controlled by a computer with high precision to adjust the rotation of the screw, it is affected by the pressing state of the raw material by the screw, the temperature of the raw material, the internal pressure of the raw material communication channel and the header, etc. The amount of raw material discharged to the header cannot be changed immediately. And even if the rotation of the screw is changed, it takes some time to respond to the raw material outlet of the header, and the delay time also differs depending on the temperature of the raw material and the amount of change in the discharge amount. The current situation is that it cannot be predicted. Therefore, conventionally, a product is molded while allowing an error within an allowable range. Therefore, an object of the present invention is to form a highly accurate molded product by discharging the raw material to the header while adjusting the discharge amount of the raw material quickly and with high accuracy.

[0004]

In order to achieve the above-mentioned object, the present invention according to claim 1 connects each extrusion mechanism of a plurality of raw materials to a molding header, and a gear pump is provided in the middle of each extrusion mechanism. By controlling the drive of the gear pump with the interposition of a multi-layered structure, it is possible to adjust the discharge amount of the raw material in each extrusion mechanism with high accuracy to form a molded product .
It is a molding device for molded products, and the extrusion mechanism is screw conveyance.
From the screw transport mechanism to the molding header.
In the middle of the communication flow path with the raw material communication flow path in
Gear pump and screw conveyor with a gear pump
In addition to associating the drive form with the structure,
An overflow valve is provided on the inlet side of the material .

According to a second aspect of the present invention, in the first aspect of the invention, a pressure sensor insertion portion is provided between the gear pump and the overflow valve, and the pressure inserted in the insertion portion is fixed. It includes a configuration in which the screw transport mechanism is controlled by a detector.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a schematic plan view showing an embodiment of the apparatus of the present invention, FIG. 2 is a schematic front view of a raw material extrusion mechanism, FIG. 3 is a front view of a main part of the extrusion mechanism, and FIG. 4 is a cross-sectional view of a molding header. Is.

As shown in FIG. 1, the molding apparatus 1 of the present invention includes a molding header 2 and three extrusion mechanisms 3-1 and 3-2.
3-3 is connected, and when the core tube a passes through the header 2, the raw materials discharged from the respective extruding mechanisms 3-1, 3-2, 3-3 coat the outer peripheral surface of the core tube a in order. Multiple layers are molded.

Each of the extrusion mechanisms 3-1, 3-2, 3-3
Since they have the same configuration, they are all given the same reference numerals. The extruding mechanism 3-1 includes a screw conveying mechanism 31 for a raw material having a screw inside a heating cylinder, and a communication channel extending from the tip of the screw conveying mechanism 31 and connected to the molding header 2. And a hopper 4 for feeding a raw material (for example, a pellet of synthetic resin) to the screw conveying mechanism 31, and the raw material fed to the hopper 4 is heated to be in a molten state, and screw feeding is performed. Pumped through mechanism 31,
It is supplied to the header 2 from the communication channel 32.

A gear pump 5 and an overflow valve 6 located between the screw conveying mechanism 3 and the gear pump 5 are provided in the communication passage 32.

The gear pump 5 is rotatably driven by the driving force of the servo motor 51 via the transmission shaft 52, and the flow rate of the raw material passing through the communication passage 32 can be adjusted with high precision. In addition, on the raw material inlet side of the gear pump 5, a pressure sensor insertion portion 53 for detecting the internal pressure of the communication channel 32.
To provide.

The overflow valve 6 interposed between the screw conveying mechanism 31 and the gear pump 5 is such that the amount of the raw material pushed out into the communication passage 32 by the screw conveying mechanism 31 is the raw material passing through the gear pump 5. When the amount is larger than the above amount, the raw material is discharged to the outside from the communication channel 32.

As shown in FIG. 4, the molding header 2 has a core material passage 21 of a core tube a as a center, and a port 31-1 to which the tip of the extrusion mechanism 3-1 is connected, etc. Port 31- to which the tip of the pushing mechanism 3-2 is connected
2, and the ports 31-3 to which the tips of the other extruding mechanisms 3-3 are connected are opened in the vicinity of the outlet 22 of the core material passage 21 with a slight displacement. Therefore, the raw materials extruded from the ports 31-1, 31-2, and 31-3 are sequentially attached to the outer surface of the core tube a passing through the core passage 21 to form a coating layer, and at the outlet 22, the core tube a is attached. Ports 31-1, 31-2, 3 on the outer peripheral surface
The raw materials from 1-3 are sequentially coated to form a tube having a plurality of layers.

The structure of the present invention is as described above, and in the case of molding a molded article having a plurality of layers, the hopper 4 of each extrusion mechanism is used.
The raw materials are put into and each extrusion mechanism 3-1, 3-2, 3-3
To feed the molten raw material under pressure to the communication channel 32, rotationally drive each gear pump 5 to control the passage amount of the raw material with high accuracy, and supply the raw material to the ports 31-1, 31-2, 31-3. The outer peripheral surface of the core tube a passing through the core passage 21 is sequentially coated with the raw material injected from each port to form a molded product having a plurality of layers.

When the shape, hardness, size and flexibility of a plurality of coating layers on the outer surface are changed in such a molding process, the rotational driving state of the gear pump of each extrusion mechanism is controlled according to a preset design, and the raw materials are controlled. Adjust the injection amount of.

In this case, the servomotor 51 is used to perform numerical control to control the rotational driving state of each gear pump 5 with extremely severe and highly accurate response to control the shape and size of the coating layer of the molded product. And the like can be molded into a predetermined shape with high precision. However, since each extrusion mechanism provided with the screw transport mechanism cannot quickly respond to a change in drive, the overflow valve 6 is provided in the middle of each communication channel 32, and the pressure sensor is attached to the insertion portion 53. By constantly detecting the pressure on the inlet side of the gear pump, it is possible to smooth the flow of raw materials and prevent wasteful consumption.

That is, when the maximum discharge amount of the gear pump 5 and the carry amount of the screw carrying mechanism are made equal, the gear pump is driven in the state of the maximum discharge amount, so that the raw material is the communication passage 32
It smoothly passes through without waste and almost never overflows. However, when the servomotor 51 is drive-controlled by the computer and the discharge amount of the gear pump 5 decreases to some extent, the overflow valve 6 operates and some raw materials passing through the communication flow path 32 are discharged to the outside.

Then, when the discharge amount of the gear pump 5 is greatly reduced, the carry amount of the screw carrying mechanism does not change, and the overflow amount of the raw material increases and it is wasted. Therefore, a pressure sensor (not shown) is attached to the insertion portion 53 to detect the pressure on the inlet side of the gear pump, and when the pressure becomes higher than a preset value, the amount conveyed by the screw conveying mechanism is reduced by numerical control by the computer. As a result, it is possible to reduce the amount of raw material overflow and reduce waste. By adopting such a function, the reproducibility of repeated changes in the injection amount of raw materials by the gear pump is extremely good, and the responsiveness to changes is extremely smooth, and the sequence assembly conditions are set according to changes in numerical values. be able to.

The present invention has been described above based on the embodiments of the drawings, but the present invention is not limited to the above embodiments, and can be carried out in any manner as long as the configuration described in the claims is not changed. be able to. In the present invention, the number of coating layers and the specific coating means are not particularly limited, and the molded product is not limited to the tube. Further, the raw material is generally a thermoplastic synthetic resin, but in addition to this, synthetic rubber and any other thermoplastic material can be used.

[0019]

In summary, according to the present invention, each extrusion mechanism for a plurality of raw materials is connected to a molding header, a gear pump is interposed in the middle of each extrusion mechanism, and the drive of the gear pump is controlled. It is characterized in that a discharge amount of raw materials in each extrusion mechanism is adjusted with high accuracy to form a molded product.

Therefore, by numerically controlling the discharge amount of the gear pump by a computer, it is possible to make a fine, highly accurate, and quick response, and therefore the fine shape, hardness, size, and flexibility of the molded product. It can correspond to. Therefore, in particular, when molding a medical tube for endoscopy of a human body, it is possible to deal with a dimensional order in the unit of micron.

Further, the extrusion mechanism is a screw conveying mechanism,
A raw material communication flow path from the screw transport mechanism to the molding header is provided, a gear pump is interposed in the middle of the communication flow channel, and the drive mode of the gear pump and the screw transport mechanism is associated with the raw material inlet of the gear pump. If an overflow valve is provided on the side, and a pressure sensor insertion part is provided between the gear pump and the overflow valve, and the screw transport mechanism is controlled by the pressure detector inserted in the insertion part, the communication flow path Not only is the raw material flowing through the container extremely quick, but it does not unnecessarily overflow, so that wasteful consumption of the raw material can be omitted and the practical value is high.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing an embodiment of a molding apparatus of the present invention.

FIG. 2 is a schematic front view showing an embodiment of a raw material extrusion mechanism.

FIG. 3 is a front view of a main part of an extrusion mechanism.

FIG. 4 is a cross-sectional view showing an example of a molding header.

[Explanation of symbols]

1 molding equipment 2 Molding header 3 Extrusion mechanism 4 hopper 5 gear pump 6 Overflow valve 21 Core material passage 22 exit 31 Screw transport mechanism 32 communication channels 51 Servo motor

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B29C 47/00-47/96

Claims (2)

(57) [Claims] 1. Discharge of raw materials in each extrusion mechanism by connecting each extrusion mechanism of a plurality of raw materials to a molding header, interposing a gear pump in the middle of each extrusion mechanism, and controlling the drive of the gear pump. Molding equipment for multi-layered molded products that adjusts the amount with high precision to mold molded products
The extrusion mechanism is a screw transport mechanism and the screw transport mechanism
Has a flow path for raw materials from the mechanism to the molding header
The gear pump in the middle of the communication flow
Associate the drive mode between the pump and the screw transport mechanism
Along with the
-A molding device for multi-layer molded products, characterized by being equipped with a valve . Wherein provided insertion portion of the pressure sensor between the gear pump and the overflow valve, a plurality of layers according to claim 1 comprising controlling the screw conveyor mechanism by the pressure detectors inserted into the insertion portion Molding equipment for molded products.