JPH081758A - Manufacture of synthetic resin-made extrusion molded product - Google Patents

Abstract

PURPOSE:To provide a method for manufacture of a synthetic resinmade extrusion molded product wherein dimensions of an aged product are settled within requirements specified in a standard. CONSTITUTION:A temperature of a surface near a cut part of an extrusion molded product 3 continuously extruded from an extruding machine 1 is detected with a temperature sensor 7. A central information processing part 8 cuts the extrusion molded product 3 while adjusting a cut length by calculating based on the detected result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a synthetic resin extruded product having a predetermined length by cutting a synthetic resin extruded product continuously extruded from an extruder.

[0002]

2. Description of the Related Art Conventionally, a method of cutting an extruded product continuously extruded from an extruder to obtain a synthetic resin extruded product such as a synthetic resin pipe having a predetermined length Adjust the sensor position so that the length is the standard, and cut the product when it hits the sensor, or contact the pulse encoder with a continuous long body that is being pushed out, and when the pulse reaches the set value, the cutting machine There is a method to cut the product.

[0003] Here, the length of the continuously extruded thermoplastic resin extruded product has the property of expanding when the temperature rises and contracting when the temperature falls. Therefore, when the extrusion molded product continuously extruded from the extruder is cut by the conventional method as described above, even if the length at the time of cutting is within the standard, the subsequent extrusion molded product is Occasionally, the product may be out of specification due to expansion and contraction, resulting in defective products.

This relationship will be described in detail with reference to FIG. FIG. 3 is a graph showing the state of changes over time in the surface temperature and the standard length immediately after the actual cutting of the polyvinyl chloride resin pipe.

That is, the relationship between the change Δt in the surface temperature of the hard vinyl chloride resin tube and the change ΔL in the length of the product of 4000 mm is as follows. ΔL = Δt × 4000 × 7 × 10 ⁻⁵ According to this, the surface temperature 120 minutes after cutting is 2
When the temperature drops from 9 ℃ to 15 ℃, the standard length is from 4007mm to 4
Shrink to 003 mm and shorten by about 4 mm.

Therefore, the surface temperature of the portion of the extruded product that is continuously extruded to be cut is delicate due to the outside air temperature due to the difference in season and time during the day and the difference in cooling conditions in the sizing die. And the length of the product changes when cut, regardless of the surface temperature.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and by taking into consideration the surface temperature at the time of cutting of an extruded product and cutting at the time of manufacturing, the product size over time is reduced. The purpose of the present invention is to provide a method for producing a synthetic resin extruded product that falls within the specifications.

[0008]

According to the present invention, a surface temperature near a cut portion of a synthetic resin extruded product continuously extruded from an extruder is detected by a temperature sensor, and based on the detection result, a central temperature is detected. It is a method of manufacturing a synthetic resin extruded product, which is calculated by an information processing unit and cuts the extruded product while adjusting the cutting length of the synthetic resin extruded product.

[0009]

The method of manufacturing the synthetic resin extruded product of the present invention is as follows.
The temperature sensor detects the surface temperature near the cut portion of the synthetic resin extruded product continuously extruded from the extruder, and the central information processing unit calculates the cutting temperature based on the detection result while adjusting the cutting length. By cutting the synthetic resin extruded product, the surface temperature of the part of the extruded product that is continuously extruded is to be cut by the outside air temperature and the sizing die depending on the season and the time difference of the day. It is possible to manufacture an extruded product made of a synthetic resin in which the size of the product over time falls within the standard even if it slightly changes due to the difference in the cooling conditions.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. FIG. 1 is a front view showing an entire molding line of a synthetic resin extruded product of the present invention. An uncured extruded product 3'which is continuously extruded from a die 2 provided at the tip of the extruder 1 is passed through the water tanks 4 and 4 to be cooled, and then by a take-up machine 5. After it is taken out, it is cut by a cutting machine 6 to obtain an extruded product 3.

A temperature sensor 7 is provided at a point A of the extruded product 3 immediately after the cutting machine 6, the surface temperature of the extruded product 3 immediately after cutting is detected by the temperature sensor 7, and the detection result is obtained. Is transmitted to the central information processing unit 8.

Based on the detection result, the central information processing unit 8 calculates the cutting length so that the length falls within the standard when the temperature reaches the specified temperature. The extruded product is cut by the cutting machine 6 based on the cutting length command from the central information processing unit 8. The method for cutting the extruded product by the cutting machine 6 is such that when the reading of the pulse encoder 9 reaches the cut instruction value, a cutting signal is output to cut the extruded product.

In order to perform the calculation in the central information processing unit 8, actual data such as the coefficient of linear expansion of the extruded product and the relationship between the surface temperature of the extruded product and the length when the temperature reaches a specified temperature are accumulated. It is necessary to do the calculation beforehand.

Therefore, first, the length of the extruded product at the point A is measured at the time of start and inspection. The surface temperature of the extruded product at that time is t, but it is desired that the length of the extruded product at a certain standard temperature t _{s be} the target value X. Therefore, the surface temperature t of the extruded product and the length L of the extruded product are L _{ts at the} standard temperature t _s , as shown in the following formula (1). The L _ts ≒ L _{[1-α (t-t s} ) ] Equation (1) alpha in said are the coefficients, the shape of the extrusion and a different depending on the material and the like.

[0015] search of the L _ts in arithmetic unit of the central processing unit 8, the difference ΔL between the target at the L _ts phrase standard temperature,
It is calculated by ΔL = X−L _ts . The cutting instruction value Y at the surface temperature t is calculated by the following equation (2). _{Y = X · L / L ts} = X / _{[1-α (t-t s} ) ] Equation (2) Therefore, as shown in FIG. 2 (a), the surface temperature of the extrudate at the point A The disconnection instruction value Y at the time of t is given by the equation (2).
The one calculated in step S1 is displayed on the control panel (central information processing unit 8).

Next, the surface temperature of the extruded product is from t to t '.
The disconnection instruction value Y ′ at the time of change is calculated by the following equation (3). Y '= Y [1 + α (t'-t)] = X [1-α (t'-t)] / [1-α (t -t _s ··· Equation (3) therefore, and FIG. 2 (b) As shown in FIG. 7, the cutting instruction value Y ′ at the surface temperature t ′ of the extruded product at the point A calculated by the equation (3) is displayed on the control panel (central information processing unit 8). .

The coefficient α in the formula (1) shows a different value depending on the shape, material, etc. of the extruded product. This data is measured by using the automatic product length measuring instrument 10 as shown in FIG. The result can be input to the central information device 8. As shown in FIG. 4, in the automatic product length measuring device 10, the length measuring parts 101,
102 are provided at a predetermined interval S. The length measuring units 101 and 102 have a pair of sensors 10 respectively.
1a, 101b, 102a, 102b are provided, and one sensor 101a, 102a side to the other sensor 1
The infrared rays R are radiated to 01b and 102b. Then, when both ends of the extrusion-molded product 3 cross between them,
It is possible to measure the light-shielding amount, calculate the lengths x ₁ and x ₂ , and measure the length of the extruded product as S + x ₁ + x ₂ .

Since the method for producing a synthetic resin extruded product of the present invention is configured as described above, it is possible to produce a synthetic resin extruded product in which the product size over time falls within the standard. .

[0018]

[Brief description of drawings]

FIG. 1 is a front view showing an entire molding line of a synthetic resin extruded product of the present invention.

2 (a) and 2 (b) are each an explanatory view showing a display example of a control panel in the present invention.

FIG. 3 is a graph showing changes in surface temperature and length of the polyvinyl chloride resin pipe with time immediately after cutting.

FIG. 4 is a front view showing an example of an automatic product length measuring instrument.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Extruder 2 Mold 3 Extruded product 4 Water tank 5 Take-off machine 6 Shearing machine 7 Temperature sensor 8 Central information processing section 9 Pulse encoder 10 Automatic product length measuring instrument

Claims (1)

[Claims] 1. A temperature sensor detects a surface temperature near a cutting portion of a synthetic resin extruded product continuously extruded from an extruder, and based on the detection result, a central information processing unit calculates a cutting length. A method for producing a synthetic resin extruded product, which comprises cutting the synthetic resin extruded product while adjusting the height.