JPH0446797A - Cutting method of extruded material - Google Patents

Abstract

PURPOSE:To obtain a cut piece practically equal to a set cut-length by selecting a shrinkage quantity stored per each extruded material on the basis of a tip position and a rear position of the extruded material, speed of carrying conveyor and temperature of the extruded material, and controlling a cutting device on the basis of the correction control signal corresponding to each selected shrinkage quantity. CONSTITUTION:The raw material rubber is extruded onto a carrying conveyor 18 by an extruder 10 comprising a connector which has a cross section corresponding to a tread and a side wall of a tyre to be formed, and is formed into a predetermined-form extruded material 12, and after cooling the extruded material 12 in a cooling vessel 16, the extruded material 12 is cut by a skiver 20 into a cut piece having a preset length. At this stage, each shrinkage quantity stored in memories 34, 40, 46 per each extruded material in relation with a tip position and a rear position of the extruded material, speed of the carrying conveyor 18 and temperature of the extruded material to be carried. The correction control signal corresponding to these shrinkage quantities is output from computing devices 50, 51, 52 to control a cutting device 20 on the basis of this control signal.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a cutting method for cutting an extruded material formed by extruding rubber, plastic, etc. into cut pieces of a predetermined length.

(Prior art) For example, treads, sidewalls, bead fillers, etc. that make up tires are usually made from raw rubber kneaded in a Banbury mixer and passed through a mouthpiece that has a gate that corresponds to the cross-sectional shape of the tread or sidewall. The extruded material is continuously extruded into an extruded material, and a conveyor installed adjacent to the extruder conveys this extruded material through a cooling tank to a skiver as a cutting device, where it is cut into tires.
It is cut to the specified length for the duty. After each shredded piece is confirmed to be within the set length range, it is generally accumulated in a stockyard equipped with shelves, etc., and taken out and used at any time during the tire molding process. It is.

In this way, confirming that the length of the shredded pieces is of a predetermined thickness is important because the weight of the tread rubber that makes up the tread portion of the tire accounts for approximately 50% of the total weight of the pneumatic tire. This is because it has a great influence on the various performances of the extruded material, and therefore, great care is taken when cutting the extruded material.

(Secret B to be Solved by the Invention) However, the extruded material forming the tread rubber is extruded from the die of the extruder, pulled by a conveyor, and furthermore forcibly cooled in a cooling tank. Since stress remains inside, there is a problem in that the extruded material and the pieces cut from it shrink after being cut. Moreover,
The amount of shrinkage varies depending on the working conditions and environment, the shape and dimensions of the extruded material, and each raw rubber, so cutting the extruded material into pieces of a certain length requires considerable experience. It happens. In particular, immediately after the cutting operation starts and just before the end, the shrinkage of the extruded material at the extrusion front end and rear end is large, making it difficult to obtain cut pieces of the desired length, resulting in a decrease in yield.

The present invention was made in view of such problems,
The object of the present invention is to provide a cutting method capable of cutting extruded materials, particularly extruded materials such as rubber or plastic, whose cutting length is difficult to maintain constant, into a predetermined length.

(Means for achieving the object) In order to achieve this object, in the method of the present invention, when cutting the extruded material conveyed by the conveyor into cut pieces of a predetermined length using a cutting device, the amount of shrinkage after cutting related to the extrusion tip and rear end positions of the extruded material;
The amount of shrinkage after cutting related to the conveyor speed and the amount of shrinkage after cutting related to the temperature of the extruded material are memorized for each extruded material, and the amount of shrinkage stored for each extruded material is applied to the extrusion tip of the extruded material. The cutting apparatus is characterized in that the cutting device is controlled based on a correction control signal corresponding to each amount of shrinkage, which is selected based on the position of the end and rear end, the speed of the conveyor, and the temperature of the extruded material.

(Function) The raw rubber is extruded onto a conveyor by an extruder equipped with a mouthpiece with a cross-sectional shape corresponding to the tread or sidewall of the tire to be molded, and is formed into an extruded material with a predetermined cross-sectional shape. After being cooled in the tank, the extruded material is cut into pieces of a preset length using a Skyper. The shredded pieces will shrink.

However, even in that case, the amount of shrinkage stored in advance for each extruded material, which is related to the positions of the leading and trailing ends of the extruded material, the speed of the conveyor, and the temperature of the extruded material being conveyed, can be calculated. Since the cutting device is controlled by a correction control signal corresponding to the selected amount of shrinkage, the length of the cut piece can be maintained at the set length.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

An extruded material cutting apparatus to which the method of the present invention is applied, which is schematically shown in FIG.
This extruded material 12 is transferred to a conveyor 18 via a cooling tank 16 by a drawer conveyor 14 disposed adjacent to the extruder 10, and then cut into cut pieces 22 of a set length by a Skyper 20. Cut in order. Then, it is confirmed that each of the cut pieces 22 has a predetermined length using a total length 24 provided on the downstream side of the SKYPER 20.

Cutting work by the Skyper 20 is performed by operating a driver 28 based on a setting signal from a cutting length setting device 26 that sets the cutting length of the extruded material. A cutting length correction calculation device 30 for correcting the length is connected, and the device 30 calculates the deviation corresponding to the measurement signal from the setting signal and adds or subtracts it to the original setting signal (that is, representing the setting length). , a correction signal representing the corrected cutting length is input to the shrinkage amount correction calculation device 50 at the next stage.

Next, in order to correct the shrinkage at the extrusion front end and rear end of the extrusion material 12, in this embodiment, the extrusion front end and rear end positions of the extrusion material 12 are detected at the extraction portion of the cooling tank 16, for example. Extruded material detection device 3 equipped with an LED as a light source and a phototransistor as its light receiving section
2 is disposed, and when the light from the light source is blocked by the extruded material 12, the positions of the extruded front and rear ends are detected. When this detection signal is input to the storage device 34 that stores shrinkage amount information corresponding to the extrusion tip and rear end positions of each extruded material, the storage device 34 stores the contraction amount information corresponding to the extrusion tip and rear end positions of the extrusion material. The shrinkage amount information related to the position is input to the shrinkage amount correction calculation device 50 connected to the storage device 34, and this shrinkage amount is added to the corrected cutting length output from the cutting length correction calculation device 30 in the previous stage. The information is added and subtracted and input as a new corrected cutting length to the shrinkage amount correction device 51 at the next stage.

Furthermore, in order to correct shrinkage changes related to the temperature of each extruded material, in this embodiment, a thermometer 38 for measuring the temperature of the extruded material 12 is disposed near the conveyor 18, and the temperature detected by the thermometer is The signal is input to the converter 42. Conversion section 4
In step 2, the relationship data (conversion coefficient) between the temperature and shrinkage amount of each extruded material is retrieved from the storage device 40 that stores the relationship between the temperature of the extruded material and the amount of shrinkage after cutting. The amount of shrinkage is determined and sent to the shrinkage amount correction calculation device 51, where this amount of shrinkage is added or subtracted from the corrected cutting length output from the shrinkage amount correction calculation device 50 at the previous stage, and a new corrected cutting length is determined. The length is inputted to the shrinkage amount correction calculation device 52 in the subsequent stage.

In addition, in order to correct the amount of shrinkage of the shredded pieces that depends on the conveyance speed of the conveyor 18, a tachometer 44 is attached directly or indirectly to the rotating wheel of the conveyor, and the detection from the tachometer 44 corresponding to the conveyor speed is detected. The signal is input to converter 48 . The conversion unit 48 stores the relationship data (conversion coefficient) between the conveyor speed and the amount of shrinkage after cutting in the extruded material in the storage device 46.
, the amount of shrinkage after cutting corresponding to the speed of the conveyor indicated by the detection signal from the tachometer 44 is determined, and this is sent to the shrinkage amount correction calculation device 52, where it is processed by the shrinkage amount correction calculation device 52 at the previous stage. The amount of shrinkage is added or subtracted from the corrected cutting length outputted by 51 to obtain a new corrected cutting length again. This is inputted to the driver 28 as a final correction control signal to control the drive of the SKYPER 20 to obtain the set cutting length. so as to obtain

By the way, as shown in FIG. 2(a), the amount of shrinkage at the extrusion tip and rear ends of the extruded material 12 cooled by the cooling tank 16 is smaller at the extrusion tip and rear ends; In the portions other than those end portions, there is a tendency for large shrinkage in a bow-like manner, and it does not depend on the length of the extruded material, that is, the length of one loft. The relationship between conveyor speed, extrusion material temperature, and shrinkage amount after cutting is as follows:
As schematically shown in FIG. 2 0)), similar trends are shown, and although these relationships differ depending on the extruded material, the relationships are unique to each extruded material.

Therefore, a preliminary test is performed for each extruded material, and the relationship between them is stored as information for each extruded material. By selecting the corresponding information based on the information power S and operating the cutting device based on the correction control signal and setting signal corresponding to each type of reduction, it is possible to obtain a cut piece of a predetermined length. can.

Incidentally, when the quality of each cut piece was examined by applying the method of the present invention and the conventional method, it was found that when the method of the present invention was used, the defect rate of pieces that deviated from the set length decreased to about 1710.

(Effects of the Invention) Thus, according to the present invention, when cutting an extruded material formed by extruding rubber, plastic, etc., cutting can be performed while correcting the set cutting length based on the amount of shrinkage that differs for each extruded material. Therefore, it is possible to provide cut pieces that are substantially equal to the set cut length.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an extruded material cutting device to which the method of the present invention is applied, and Figs. 2 (a) and (c) show the extrusion tip and rear end positions of the extruded material, the conveyor, and the extrusion FIG. 2 is an explanatory diagram qualitatively showing changes in shrinkage amount with respect to material temperature. 10 - Extruder 12 - Extruded material 18 - Conveyor 20 - Sky bar 22 - Cutting piece 24 - Length meter 26 - Cutting length setting device 28 - Driver 3 - Cutting length correction calculation device 42 .48-Conversion unit 50.51.52-Shrinkage correction calculation device 34.40,4
6-Storage device

Claims (1)

[Claims] 1. When cutting the extruded material conveyed by the conveyor into pieces of a predetermined length using a cutting device, the amount of shrinkage after cutting related to the extrusion tip and rear end positions of the extruded material and the conveyance The amount of shrinkage after cutting related to the conveyor speed and the amount of shrinkage after cutting related to the temperature of the extruded material are stored for each extruded material, and the amount of shrinkage stored for each extruded material is
selected based on the extrusion tip and rear end positions of the extruded material, the conveyor speed, and the extruded material temperature,
A method for cutting an extruded material, comprising controlling a cutting device based on a correction control signal corresponding to each amount of shrinkage.