JPH06312454A - Production of heat-shrinkable article - Google Patents

Abstract

PURPOSE:To continuously produce a heat-shrinkable article using a preformed product large in thickness by a method wherein the ridges of a molded product for a heat-shrinkable sheet are grasped while the molded product is fed in a softened state to laterally stretch the molded product and held to a parallel state to cool and cure the stretched one. CONSTITUTION:A pair of endless tracks 1 are rotated in mutually reverse directions along go-around routes 2, 3 and these routes 2, 3 are partially opposed left and right. Stretching parts 4 gradually wide in the opposed interval W therebetween and parallel parts 5 definite in the opposed interval W are set to the opposed parts of the routes 2, 3 and guide members 6 are arranged thereto. The guide members 6 and the routes 2, 3 are moved by an interval control mechanism 7 to control the opposed interval W. A cooling mechanism is arranged to the parallel parts 5. The endless tracks 1 are constituted by connecting a large number of grasping jigs 9 in a loop form by chains 10. A preformed product A is fed while the ridges (a) thereof are grasped and laterally stretched to be cooled and cured.

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 heat-shrinkable article in which a belt-shaped material to be stretched is continuously conveyed in the longitudinal direction and stretched in the width direction.

[0002]

2. Description of the Related Art A method for producing a heat-shrinkable article, for example, a heat-shrinkable sheet for protecting a connecting portion of a cable is described in the following: ) Are drawn one by one. Conventionally, a stretching device used for such a stretching method includes, for example, a pair of gripping tools arranged in an opposed state, and a moving mechanism that relatively moves these gripping tools in the facing direction,
The preform which has been preheated and softened is grasped on both sides by a gripping tool and stretched by pulling on both sides. That is, in the case of a heat shrinkable sheet,
Short preforms for several heat-shrinkable sheets are drawn one by one.

[0003]

The productivity is not so good if the short preforms are taken out one by one and stretched. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a heat-shrinkable article that can be stretched in the width direction while continuously transporting a strip-shaped material to be stretched in its longitudinal direction. It is to provide a manufacturing method.

[0004]

SUMMARY OF THE INVENTION The present invention continuously provides a long pre-formed product A for heat-shrinkable sheet, which has a strip shape and is provided with a projecting strip a projecting near both side edges thereof. After extrusion molding, the preform is conveyed in its longitudinal direction while being held in a softened state, and the ridges on both sides are gripped and tension is applied to the ridge. It is characterized in that it is gradually spread in the width direction and stretched, and then held in a parallel state and cooled and hardened.

When the track is rotated around the endless track, each gripping tool is pressed and closed by the guide member near the rear end of the extending portion (both chucking blocks are brought close to each other), and the guide member is pressed near the front end of the extending portion. Escape and open (separate both chucking blocks). Therefore, by feeding the tip of the softened strip-shaped material to be drawn between both endless tracks, each gripping tool of both endless tracks in the vicinity of the rear end of the stretched part sequentially holds both chucking blocks on both side edges of the material to be drawn. It is gripped between and conveyed in the circling direction. Then, in the stretching part, the facing interval between the circulation paths gradually widens, so that the gripping tool stretches the preform A (material to be stretched) in the width direction while conveying the material to be stretched. At this time, a large tension is applied from the inside of the side surface of the ridge a projecting near the side edges of the preform A toward the outside. Then, the grip of the preform A (material to be stretched) is released near the front end of the stretching portion, and the preform A is circulated again near the rear end of the stretching portion. After the stretching step, both side edges of the stretched preform A are cooled and hardened by the cooling mechanism 8 while being held in parallel. The long heat-shrinkable sheet thus manufactured is sequentially cut into a certain length in the next cutting step to manufacture a heat-recoverable article.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of an apparatus for carrying out the method of the present invention, in which reference numerals 1 and 1 are a pair of endless tracks. These endless tracks 1 and 1 are made to rotate in opposite directions along respective circulation paths (paths formed by the chain guide 2 and the sprocket wheel 3) laid so as to draw a loop in a substantially horizontal plane. It is arranged such that a part of the two orbiting paths face each other on the left and right. In the opposing portions of the two orbiting paths, the opposing distance W gradually extends toward the front in the traveling direction of the endless track 1 (the orbiting direction in the opposing portions, that is, the direction of arrow A in FIG. 1), and the extending portion 4. Continuing in front of section 4 and facing interval W
And a parallel portion 5 having a constant value are formed. In addition, the stretching section 4
A guide member 6 for pressing a chucking block, which will be described later, is disposed on the circulation path from the rear position to the parallel portion 5. For example, as shown in FIG. 2, the guide member 6 inclines so that the portion behind the extending portion 4 gradually lowers its height toward the front, and the portion on the front side from the extending portion 4 to the parallel portion 5. Is a rail whose height is constant. The guide member 6 and the circulation path (that is, the chain guide 2 and the sprocket wheel 3) are configured to be movable in the facing direction (the direction of arrow B in FIG. 1). An interval adjusting mechanism 7 that adjusts the interval W is continuously provided on both circulation paths. Further, a cooling mechanism 8 (see FIG. 2) that blows a refrigerant (for example, cool air or cooling gas) into the space between the parallel portions 5 is disposed above and below the parallel portion 5.

On the other hand, the endless track 1 has a large number of grippers 9 ...
It is made by connecting the chains in a loop with the chain 10.
Each gripping tool 9 includes a pair of upper and lower chucking blocks 11 and 12 as shown in FIG. The lower chucking block 11 is fixed to the chain 10, the upper chucking block 12 is connected to the lower chucking block 11 via a rod 13 so as to be vertically slidable (approachable), and It is biased upward (separation direction) by the spring 14. The chucking block 12 on the upper side is provided with an engaging groove 15 on the lower surface thereof along the extending direction of the endless track 1.

Next, the operation method and operation of the apparatus for stretching the preformed product (reference numeral A in the figure) of the heat-shrinkable sheet by using the continuous stretching apparatus thus constructed will be described. However, the preformed product A is, for example, a continuously extruded strip-shaped plastic molded product, and ridges a, a protruding from one surface thereof are formed on both side edge portions thereof as shown by a chain line in FIG. It has been done.

First, the gap adjusting mechanism 7 is operated to move the chain guide 2, the sprocket wheel 3 and the like in the facing direction to set the facing distance W between the circulating paths to a desired distance. That is, the facing distance W near the rear end of the stretched portion 4 is matched with the width dimension of the preform A, and the facing distance W in the parallel portion 5 is matched with the width dimension after stretching (width dimension determined by a desired stretch ratio). . Then, the cooling mechanism 8 is activated and the sprocket wheel 3
Is driven to orbit the endless orbits 1 and 1 continuously. At this time, since the chucking block 12 on the upper side is biased upward by the spring 14, each gripping tool 9 moves along the circular path with the chucking blocks 11 and 12 separated from each other as shown in the right end of FIG. Try to run to. But,
When approaching the opposing portion of the circulation path, the guide member 6 presses the upper surface of the upper chucking block 12 and gradually guides it downward (approaching direction), so that each gripping tool 9 moves to the rear end of the extending portion. By the time it reaches the position, it completely closes as shown in FIG. 3 (the chucking blocks 11 and 12 are brought close to each other), and when passing through the parallel portion 5, it escapes the pressing force of the guide member 6 and the chucking block 12 on the upper side rises. So open again (separate both chucking blocks 11 and 12)
Such an operation is performed.

In such an operating condition, when the preformed product A which has been preheated and softened is made substantially horizontal and the tip thereof is fed from the rear of the extension part 4 into both endless tracks 1 and 1, firstly, the extension part is drawn. The gripping tool 9 approaching to the rear position of is closed and grips both side edges of the preform A between the chucking blocks 11 and 12. At this time, the engaging groove 15 of the chucking block 12 on the upper side engages with the ridges a of the preform A as shown by the chain line in FIG. And the first gripper 9
As the front end of the preform A is conveyed in the traveling direction, the subsequent grippers 9 ... Grasp the preform A one after another and convey it in cooperation. Next, when the gripping tools 9 ... In the gripping state approach the extending portion 4, the facing distance W between the two orbiting paths gradually increases, so that the gripping tools 9 on both endless tracks 1 gradually increase the distance between each other. Therefore, while conveying the grasped preform A in the longitudinal direction (direction of FIG. 1A), it is stretched in the width direction (direction of FIG. 1B). At this time, a reaction force against the tension at the time of stretching is generated in the preform A, and this reaction force tends to disengage both side edges from the gripper 9, but the engagement groove 15 and the protrusion a are engaged with each other. Prevents this. Then, when the gripping tools 9 ... Are approaching the parallel part 5, the cooling mechanism 8 cools the preform A immediately after stretching from above and below. Due to this cooling action, the preform A after stretching is
Since both side edges are hardened in a gripped state (tensioned by tension), the corrugation phenomenon of the sheet that tends to occur after gripping and releasing is unlikely to occur. After that, the gripping tools 9 ... Reach the rear end of the parallel part 5 and reach both chucking blocks 1.
1 and 12 are separated from each other, the preform A after stretching is released, and the preform A is circulated to the rear position of the stretching section 4 again. Therefore, the released preform A is continuously conveyed as it is to the next step, that is, the cutting step, or wound on a bobbin or the like.

On the other hand, FIGS. 4 to 6 show another embodiment of the present invention. In these figures, the endless track 16 ・ 16
Are circulated in the same direction along each looping path that draws a loop in a substantially vertical plane, and part of both looping paths are arranged so as to face left and right. That is, in this case, the endless track 16 is formed by connecting a large number of gripping tools 9 ... With the so-called curved chain 17. Since such a stretching device has a circular path of the endless track 16 in a vertical plane, it occupies a smaller area than the stretching device of the above-described embodiment, and is suitable for installation in a limited space.

In the above-mentioned embodiment, the both circulation paths are opposed to each other in the left and right directions, but they may be opposed to each other in any direction such as up and down or obliquely. Further, in the embodiment, the upper chucking block 12 is biased upward by the spring 14, but, for example, the chucking blocks 11 and 12 are arranged upside down, and the chucking block 12 is biased downward by gravity. And this chucking block 1
It is also possible to adopt a structure in which 2 is pushed upward by a guide member. Further, a belt may be used instead of the chain 10 or the curved chain 17, and the chucking blocks 11 and 12 may be hinged instead of being connected via the rod 13.

[0013]

According to the present invention, a long pre-formed product A for heat-shrinkable sheet is continuously extruded in the form of a strip and provided with protrusions a projecting near the both side edges thereof. After the molding, the preform is conveyed in its longitudinal direction while being held in a softened state, and the ridges on both sides are gripped and tension is applied to the ridge so that its width direction is increased. It is constructed so that it is gradually spread out and stretched, and then it is held in a parallel state and is cooled and hardened. The projected ridges can be securely gripped one after another, and in addition, the ridges can be used to perform stretching with a large tension. Therefore, a heat-shrinkable article can be continuously produced using a long preform for a heat-shrinkable sheet having a large thickness.

[Brief description of drawings]

1 is a schematic plan view showing an embodiment of an apparatus for carrying out the method of the present invention.

FIG. 2 is a view taken along the line II-II of FIG.

FIG. 3 is a view taken along the line III-III in FIG.

FIG. 4 is a schematic plan view showing another embodiment of the present invention.

5 is a view taken along the line VV of FIG.

6 is a view taken along the line VI-VI of FIG.

[Explanation of symbols]

 1 endless track 4 extended part 5 parallel part 6 guide member 7 spacing adjusting mechanism 8 cooling mechanism 9 gripping tool 10 chain 11 chucking block 12 chucking block 14 spring 15 engaging groove 16 endless track 17 curved chain A preform a protrusion Article W Opposing interval

Claims (1)

[Claims] 1. A continuous preform A for a heat-shrinkable sheet, which has a strip shape and is provided with protrusions a protruding near the both side edges thereof, is continuously extruded, and then the preliminary While the molded product is held in the softened state, the preformed product is conveyed in the longitudinal direction thereof, and the ridges a on both sides are gripped, and tension is applied to the ridge to gradually widen the width direction. A method for producing a heat-shrinkable article, which comprises stretching, and then maintaining this in a parallel state and cooling and curing.