JPH058118Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a stretching machine for stretching a belt-like object such as a thermoplastic resin film.

(Prior Art) A conventional belt-shaped object stretching machine will be explained with reference to FIG. 6) and guide it to the next preheating roll (a preheating roll that heats the film 6 to a temperature suitable for stretching) 2, and the lower speed side take-up roll 1 may also serve as a heating roll. be. Further, reference numeral 3 denotes a low-speed stretching roll, which is provided for stretching the film 6, and may also serve as a heating roll. Further, numerals 11, 12, and 13 are Nippro rolls, and the Nippro rolls 11, 12, and 13 bring the film 6 into close contact with the mating roll to prevent air from entering between the rolls 1, 2, and 3 and the film 6. , are provided to improve heat transfer from the rolls 1, 2, 3 to the film 6. The above is the low speed side. Next, the high speed side will be explained. 4 is a high speed stretching roll, and the film 6 is stretched by the difference in circumferential speed between the low speed stretching roll 3 and the high speed stretching roll 4. The high-speed stretching roll 4 also serves as a cooling roll. A high-speed take-up roll 5 is provided for taking the film 6 from the high-speed stretching roll 4 and sending it to the next process. The high-speed take-up roll 5 may also serve as a cooling roll. Also, 14 and 15 are nipprol, and the same nipprol 1
4 and 15 are for bringing the film 6 into close contact with the mating roll to prevent air from entering between the rolls 4 and 5 and the film 6, and to improve heat transfer from the rolls 4 and 5 to the film 6. It is set in. Note that the film 6 is made of polypropylene,
Thermoplastic resins such as polyethylene terephthalate, polystyrene, and polyethylene. The film 6 is heated to a temperature suitable for stretching by a preheating roll 2 and a low-speed stretching roll 3, and then stretched by a low-speed stretching roll 3 and a high-speed stretching roll 4.

FIG. 4 shows another conventional example in which a nip roll 21 is added to the low-speed stretching roll 3. The nip roll 21 is disposed near the contact point on the film exit side of the low-speed stretching roll 3, and has the same rubber hardness as the nip roll 13.

(Problems to be Solved by the Invention) In the conventional strip stretching machine shown in FIG.
When the film 6 is stretched due to the difference in circumferential speed between them, the stretching point of the film 6 may not be fixed on the stretching space A depending on the state of the friction coefficient between the low-speed stretching roll 3 and the film 6. There was a problem in that the film returned to the low-speed stretching roll 3 side, causing uneven stretching in extreme cases.

In order to eliminate this stretching unevenness, a nip roll 21 is disposed near the contact point on the film exit side of the low-speed stretching roll 3, as shown in FIG. In this case, uneven stretching can be prevented, but the Nippro roll 21
An air pocket is formed between the nipped film 6 and the low-speed stretching roll 3, as shown in FIG. 4B, and the stretching machine cannot operate stably. The reason why this air pocket occurs is that although the film 6 is brought into close contact with the low-speed stretching roll 3 by the nip roll 13, a small amount of air passes between the nip roll 13 and the film 6, and it is transferred to the next nip roll 21. This is due to being blocked by and accumulating.

(Means for Solving the Problems) The present invention addresses the above-mentioned problems by disposing nip rolls near the inlet side contact point and near the outlet side contact point of the low-speed stretching roll of the strip, and This relates to a stretching machine for strips, characterized in that the rubber hardness of the Nippro roll is made softer than the rubber hardness of the nippro roll on the exit side, and its purpose is to return the stretching point of the strip to the low speed stretching roll side, An object of the present invention is to provide an improved stretching machine for a strip-like material that can prevent air from being trapped in the nip roller section on the exit side of the stretching roll.

(Function) As mentioned above, in the stretching machine for a strip of the present invention, the rubber hardness of the nip roll on the inlet side is softer than that of the nip roll on the outlet side. is better than the degree of adhesion between the strip and the low-speed stretching roll at the nip roll portion on the exit side. Therefore, the amount of air entrained between the strip and the low-speed stretching roll is reduced, and even if the entrained air is blocked at the nip roll section on the exit side, more air passes through and is accumulated in this section. air pockets are prevented. Further, the outlet side nip roll has the above-mentioned hardness, and the exit side nip roll prevents the stretching point from returning.

(Example) Next, the stretching machine for a strip according to the present invention will be explained with reference to an embodiment shown in FIG. , 5 is a high-speed side take-up roll, 6 is a film (strip-like material), 11, 12, 14, 15 are nip rolls, 33 is a nip roll for preventing air entrainment on the inlet side, 31 is a nip roll on the exit side, The inlet side nip roll 33 is the film 6
is arranged near the inlet side contact point of the low-speed stretching roll 3,
The exit side nip roll 31 is disposed near the exit side contact point of the low speed stretching roll 3 of the film 6, and the rubber hardness of the inlet side nip roll 33 is softer than the rubber hardness of the exit side nip roll 31.
Incidentally, the film 6 is made of polyethylene terephthalate. Ethylene-propylene rubber is used for the inlet side nip roll 33, and its hardness is Hs 50°, and ethylene-propylene rubber is used for the outlet side nip roll 31, and its hardness is Hs 70°.

Next, the operation of the stretching machine for the strip shown in FIG. 1 will be explained in detail. Since the hardness of the inlet side nip roll 33 is softer than the hardness of the outlet side nip roll 31, the degree of adhesion between the film 6 and the low speed stretching roll 3 at the inlet side nip roll 33 portion is lower than that at the exit side nip roll 31 portion. 3
The degree of adhesion between the film 6 and the low-speed stretching roll 3 is better than that between the film 6 and the low-speed stretching roll 3. There is more air, no accumulation, and air pockets are prevented. In addition, the reversal of the stretching point is prevented by the outlet side nip roll 31 having the above-mentioned hardness.

When the inlet side nip roll 33 and the outlet side nip roll 31 were made to have the same hardness (Hs70°), air pockets were generated in the outlet side nip roll 31 portion. In addition, the hardness of the Nippro roll 33 on the inlet side
Set Hs to 85° and set the hardness of Nippro roll 31 on the exit side.
When Hs was set to 70° (the hardness of the nip roll 33 on the inlet side was made harder than the hardness of the nip roll 31 on the outlet side), the nip roll 33 on the inlet side could not nip uniformly, and air pockets occurred in the nip roll 31 part on the exit side. .

Next, the belt-like stretching machine of the present invention will be explained with reference to other embodiments shown in FIG.
2, 14, 15 are the same parts as above, 43 is a nip roll for preventing air entrainment on the inlet side,
41 is a nip roll on the exit side; 42 is an intermediate nip roll for preventing air entrainment; the nip roll 43 on the inlet side is disposed near the contact point on the inlet side of the low-speed stretching roll 3 of the film 6; The rubber hardness of the nip roll 43 and intermediate nip roll 42, which are disposed near the contact point on the exit side of the low-speed stretching roll 3, is softer than that of the nip roll 41 on the exit side. Incidentally, the film 6 is made of polyethylene terephthalate. Also, the entrance side Nitsuprol 4
3. Ethylene-propylene rubber is used for the intermediate nip roll 42 and the outlet nip roll 41.

Now, the hardness of the nipple roll can be changed to soft, soft,
The hardness of the inlet side nip roll 43 is divided into four levels: medium and hard.
When the hardness of the nip roll 41 on the exit side is soft and the hardness of the nip roll 41 on the exit side is medium, the hardness of the nip roll 43 on the inlet side is softer than the hardness of the intermediate nip roll 42, so the film 6 and the low speed stretching roll 3 at the nip roll 33 part on the inlet side The degree of adhesion between the film 6 and the low-speed stretching roll 3 is better than that between the film 6 and the low-speed stretching roll 3 at 42 parts of the intermediate nip roll. Therefore, the amount of air trapped between the film 6 and the low-speed stretching roll 3 is reduced, and even if the trapped air is blocked by the intermediate nip roll 42 portion, the amount passing through this portion is greater. No accumulation and no air pockets.
Further, since there is the same hardness difference between the intermediate nip roll 42 and the outlet side nip roll 41, the same effect is achieved and no air pockets are generated in the outlet side nip roll 41 portion. In addition, the stretching point is prevented from returning to the drawing point by the exit side nip roll 41, so that the drawing machine can be stably operated. The intermediate nip roll 42 also has the following effect. That is, even if the amount of air entrained in the inlet side nip roll 43 increases due to insufficient adjustment of the thickness of the film 6 at the start of operation, surface changes that occur over time, or disturbances, the amount of air entrained by the inlet side nip roll 43 is blocked by the intermediate nip roll 42. , does not affect the exit side nip roll 41 immediately before stretching.

Furthermore, if the hardness of the inlet side nip roll 43 and the intermediate nip roll 42 is made soft as described above (if they are made the same), some air pockets will occur in the intermediate nip roll 42, but the hardness will be lowered between the intermediate nip roll 42 and the outlet side nip roll 41. The difference is that the above effect is achieved and no air pockets are generated in the outlet side nip roll 41 portion.

Note that when the hardness of the inlet side nip roll 43 is set to the above hardness, the hardness of the intermediate nip roll 42 is set to the above hardness, and the hardness of the outlet side nip roll 41 is set to the above hardness, a large amount of Air pockets occur, making stable operation of the drawing machine impossible.

Note that the constituent material of each Nipprol is not limited to the above examples, and silicone rubber, Hypalon rubber, etc. can also be used.

(Effect of the invention) As mentioned above, the rubber hardness of the inlet side nip roll is softer than the rubber hardness of the outlet side nip roll in the stretching machine for a strip of the present invention, so that the belt at the inlet side nip roll part and the low speed stretching roll are The degree of adhesion is better than the degree of adhesion between the strip and the low-speed stretching roll at the exit side nip roll portion. Therefore, the amount of air entrained between the strip and the low-speed stretching roll is reduced, and even if the entrained air is blocked at the nip roll section on the exit side, more air passes through and is accumulated in this section. This prevents air from becoming trapped. Further, the outlet side nip roll has the above-mentioned hardness, which has the effect of preventing the stretching point from returning back.

[Brief explanation of the drawing]

FIG. 1 is a side view showing one embodiment of a stretching machine for a strip according to the present invention, and FIG. 2 is a side view showing another embodiment.
FIG. 3 is a side view showing a conventional belt-like stretching machine, and FIG. 4 is a side view showing another conventional example. 3...Low-speed stretching roll, 6...Band-like material, 33 or 43...Entrance side nip roll, 31 or 4
1...Nitsprol on the exit side.

Claims (1)

[Scope of utility model registration request] A strip-like article characterized in that nip rolls are arranged near the contact point on the inlet side of the low-speed stretching roll and near the contact point on the outlet side of the strip article, and the rubber hardness of the nip roll on the inlet side is made softer than the rubber hardness of the nip roll on the exit side. Stretching machine.