JP3299084B2 - Mandrel connection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for connecting a mandrel. More specifically, it is a method of connecting a synthetic resin or rubber mandrel used as a core material mainly when manufacturing rubber hoses, which can be easily connected, and from a vulcanized rubber hose to a mandrel When removing the mandrel, it is possible to easily secure a cavity for applying water pressure to the end of the mandrel, and it is not necessary to cut the mandrel itself, so the mandrel can be used many times. .

[0002]

2. Description of the Related Art An ordinary rubber reinforced hose is formed of three layers, an inner rubber layer, a reinforcing layer, and an outer rubber layer. The inner rubber layer is formed of natural rubber, synthetic rubber, or the like, and the reinforcing layer is formed of three layers. The outer surface rubber layer is formed from a synthetic rubber or the like.

The steps of manufacturing such a reinforcing hose include a step of forming an inner rubber layer by extruding raw rubber around a flexible mandrel, a step of forming a reinforcing layer, a step of forming an outer rubber layer, It comprises a vulcanization step, a step of cutting the rubber hose after vulcanization together with the mandrel, and a step of pulling out the mandrel from the rubber hose.

[0004] The mandrel is used as a core material of raw rubber which is easily deformed to secure a predetermined inner diameter. There is a limit to the length of one of these for reasons such as securing the nature. Therefore, the typical length of the mandrel is 100-300 m.

[0005] On the other hand, extrusion of rubber for forming the inner rubber layer and the outer rubber layer is performed in consideration of work efficiency.
It is preferably performed continuously, and the next mandrel is connected to the terminal after the previous mandrel one after another and sent to each step.
Conventionally, the following four methods are known as this connection method (see FIGS. 5 to 8).

A method of screwing heatons (fish hook-like connecting fittings) 53, 54 into both ends of the mandrels 51, 52 and connecting them directly or by a wire 55 (not necessarily made of metal) (see FIG. 5); A method in which the mandrels 63 and 64 are integrated by a resin injection 62 in a mold 61 (see FIG. 6), high-frequency dielectrics 73 and 74 are buried in desired positions of the mandrels 71 and 72 in advance, and dielectric heat is generated. A joining method (see FIG. 7) and a joining method in which the end faces are melted by a burner or electric heat.

[0007]

However, in the above-described method of connecting with a heaton, as shown in FIG. 5, when the mandrels 51 and 52 are pulled out of the rubber hose 56, the corners 51a or 52a of the ends of the mandrel are formed. There is a problem that the inner diameter side of the rubber hose 56 is hardly bitten out. In addition, since the strength of the portion where the heatons 53 and 54 are screwed is weak and cannot be reused after vulcanization, it is necessary to reattach the heatons. For this reason, the portion where the heaton was previously attached (the end of the mandrel) must be cut off to expose the new end, which reduces the overall length of the mandrel and limits the number of times the mandrel can be used. Also occurs. Furthermore, such a mandrel 51,
At the connecting portion 52, there is also a problem that the raw rubber easily flows into the inside and a step is likely to occur. Such a step is not preferable because there is a possibility that the rubber may be broken in the step of forming the inner rubber layer. Heaton can be wrapped around with tape to fill the steps, but a human must intervene each time the connection passes. Further, in the batch production method, it is necessary to make the mandrel a fixed size, but there is a problem that cutting the mandrel itself to a fixed length is expensive as an apparatus.

[0008] On the other hand, the joining method by injection is a joining method that does not cause a step, but it has a problem that it takes time to join the mandrel and requires expensive facilities and technical skills. Not a target.

In the joining method using welding such as dielectric heating or a burner, the equipment is relatively inexpensive, but centering is difficult, and there is a problem that a step 75 occurs at the connecting portion.

Further, by any of the above methods,
A problem remains in the process of pulling out the mandrel from the rubber hose after vulcanization. That is, as shown in FIG. 8, the mandrel 81 is pulled out of the rubber hose 82 by applying water pressure in the direction of the arrow to the end of the mandrel 81.
End 82a must be clamped. Therefore, in the related art, the end 82a of the hose 82 was manually pulled to secure a small cavity 83. However, such a work is manually performed, and requires a hang and is inefficient. there were.

In view of the circumstances described above, the present invention makes it possible to connect mandrels in a short time, is low in cost, easily secures a cavity for applying water pressure, and can be used repeatedly. It is an object of the present invention to provide a method of connecting a mandrel that can be used.

[0012]

According to the present invention, there is provided a method for connecting a mandrel, comprising the steps of: (a) having an outer diameter substantially equal to the inner diameter of a connecting tube having an outer diameter equal to the outer diameter of the mandrel; (B) attaching a connection jig having a groove to an end of the mandrel by screwing or injection molding, and (b) applying an adhesive to the outer periphery of the connection jig and then inserting the connection tube. It is characterized by becoming.

(A) A connecting jig in which a male thread portion having an outer diameter slightly larger than the inner diameter of a connection tube having an outer diameter equal to the outer diameter of the mandrel is formed on a part or the whole of the surface. Is attached to the end of the mandrel by screwing or injection molding, and (b) a step of press-fitting the connection tube into the connection jig.

Further, (a) a claw which can be inserted into the inner diameter side of a connection tube having an outer diameter equal to the outer diameter of the mandrel, and which bites into the inner diameter side of the connection tube when trying to pull out the inserted connection tube. A step of attaching a connecting jig having a portion formed therein and easily connecting by simply inserting the connecting tube to the end of the mandrel by screwing or injection molding; and (b) inserting the connecting tube into the connecting jig. It is characterized by comprising a step.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for connecting a mandrel according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an explanatory view of a method of connecting a mandrel according to claim 1, FIG. 2 is a view illustrating a method of pulling out a mandrel from a rubber hose, and FIG. 3 is an explanatory view of a method of connecting a mandrel according to claim 2. FIG. 4 is an explanatory view of a method for connecting a mandrel according to claim 3.

In FIG. 1, 1 is a mandrel, 2 is a connection tube, and 3 is a connecting jig.

The mandrel 1 is a flexible solid cylinder or solid rod made of a synthetic resin such as TPX (methylpentene resin), the outer diameter of which is used for centering. It depends on the size of the rubber hose,
It is usually 3 mm to 25 mm, and its length is 100 mm.
m to 300 m.

The connecting tube 2 is a member for connecting the two mandrels 1 and is interposed at the connecting portion. Therefore, the length L needs to be at least twice the length L1 of the connecting jig 3, the outer diameter of the connecting tube 2 is equal to the outer diameter of the mandrel 1, and the inner diameter D is the outer diameter D1 of the connecting jig 3. Is almost equal to The connection tube 2 is made of a synthetic resin such as nylon, and has flexibility like the mandrel 1.

The connecting jig 3 has an outer diameter D1 substantially equal to the inner diameter D of the connecting tube 2 and the end 1 of the mandrel 1.
a is buried so that its central axis coincides with the central axis of the mandrel 1. The connecting jig 3 can be formed from carbon steel or the like, but it is preferable to use a metal or the like that responds to the magnetic sensor, since a cutting location in the cutting step can be easily detected. A spiral groove 4 is formed on the outer periphery for stabilizing the adhesion of the tube. The groove 4 is not limited to a spiral shape but may be an annular shape or the like, and is preferably a long groove that intersects with the direction in which the tube comes off. If the adhesive strength of the adhesive is secured, the surface may be smooth without forming such a groove 4.

The connecting jig 3 is attached to the end 1a of the mandrel 1 by screwing or injection molding. That is, as shown in FIG.
A thread 3a is formed at the end of the mandrel 1 side of
A screw hole 1b is also formed in the end 1a on the mandrel 1 side so as to withstand repeated use, and can be attached by screwing. Also, in the injection molding, the connecting jig 3 can be inserted, and the protective cover and the screw 3a which are hard to inject the molding agent into the surface of the connecting jig 3 are 3 mm or more.
By injecting a molding agent equivalent to the material of the mandrel between the mandrel 15 mm apart, the mandrel 1
The connecting portion 3 can be formed at the end 1a of the connecting member.

The tolerance of the outer diameter of the connection tube 2 is set at a centering accuracy of the connecting jig 3 of 0 mm to 0.2 m so that a step is not generated inside the rubber hose at the outer periphery of the connecting portion.
m, for example, a mandrel outer diameter of -0.1 mm to
Suitably, it is in the range of the outer diameter of the mandrel + 0 mm.
Further, it is appropriate that the inner diameter tolerance of the connection tube 2 is in the range of the outer diameter of the connecting jig ± 0.05 mm so that the connecting jig 2 does not come off.

The mandrel shown in FIG. 1 is connected by an adhesive. As the adhesive, various adhesives such as a cyanoacrylate adhesive can be used, but it is preferable to use a cyanoacrylate adhesive in consideration of deterioration due to the vulcanization step and release property in the mandrel removal step.

Next, an embodiment of the method for connecting a mandrel of the present invention will be described with reference to FIG. First, the connection jig 3 is screwed into the screw holes 1b formed at both ends of the mandrel 1. Next, a few drops of a cyanoacrylate-based adhesive are applied to the connecting jig 3. In this case, care should be taken because a large amount of coating will result in insufficient adhesion due to insufficient drying. And
Before the adhesive is dried, the connection tube 2 is inserted into the connection jig 3.

The mandrel thus connected is:
It is used as a centering member in the process of manufacturing a rubber hose. First, an inner rubber layer is formed around the rubber hose. after that,
A reinforcing layer, an outer rubber layer, and the like are sequentially formed. In the cutting step, the connection jig 3 is detected using a magnetic sensor, and the connection tube between the connection jigs is cut with a blade using an air cylinder. After that, it reaches the vulcanization process. As a result, a rubber hose having a specified length can be easily obtained, and an effect that a cavity for inserting the nipple can be secured at the same time by cutting the hollow connecting pipe.

FIG. 2 shows an example of a method for pulling out the mandrel 1 from the rubber hose 6. In the present invention, since the hollow connection tube 2 is cut as described above, the cavity 9 is secured at the end of the cutting step, and the nipples 7 and 8 are inserted into the cavity 9 and the rubber hose 6 is cut. And the connecting tube together. In this state, if water pressure is applied in the direction of the arrow, the mandrel 1 is pulled out of the rubber hose 6 leaving the connection tube 2.

FIG. 3 is a view for explaining a method of connecting a mandrel according to the second aspect of the present invention.
1 is a mandrel, 32 is a connection tube, and 33 is a connection jig.

The shapes, sizes, materials, and the like of the mandrel 31 and the connection tube 32 are substantially the same as those of the mandrel 1 and the connection tube 2 shown in FIG. It is preferable that the distance be in the range of 0.05 mm to the outer diameter of the connection jig + 0.1 mm.

The connecting jig 33 is replaced with a screw part 34 instead of the groove 4.
The configuration is the same as that of the connecting jig 3 shown in FIG. The outer diameter D2 of the external thread portion 34 is slightly larger than the inner diameter D of the connection tube 32, and
If you press in by screwing 2 in, it will not come off easily. This connecting jig 33 is also attached to the end of the mandrel 31 by screwing or injection molding.

FIG. 4 is a view for explaining a method of connecting a mandrel according to the third aspect of the present invention. In FIG. 4, reference numeral 41 denotes a mandrel, reference numeral 42 denotes a connection tube, and reference numeral 43 denotes a connection jig.

The shapes, sizes, materials and the like of the mandrel 41 and the connection tube 42 are the same as those of the mandrel 1 and the connection tube 2 shown in FIG.

The connecting jig 43 has a front end 43a and a rear end 4a.
3b and the base 43c.
The rear end 43b is screwed into the rear end 4a.
3b is provided so as to be slidable. The claw 44 is inserted between the root 43c and the rear end 43b. The connecting jig 43 can be made of stainless steel or the like.

The claw portion 44 has a substantially cylindrical shape and is made of spring steel or the like. The distal end 44b of the claw portion 44 is equally divided into six in the circumferential direction, and an elongated cut is provided from the distal end 44b side toward the root direction. The claw portion 44 is made of a flexible member and has a tip 44 in a natural state.
The outer diameter D3 of the connecting jig 43 is urged to be larger than the outer diameter of the connecting jig 43. The outer diameter D3 of the tip 44b is
It is larger than the inner diameter D of the connection tube 42. The tip 44b of the claw portion 44 has a jaw portion 44c so that the claw portion 44 can be hooked on the inner diameter side of the connection tube 42 with respect to the force in the pulling-out direction. On the other hand, when the connection tube 42 is inserted, the distal end portion 43 a is retracted, and the belly 44
When a is pressed, the distal end 44b of the claw portion 44 is reduced in diameter, becomes substantially equal to the outer diameter of the connecting jig 43, and the jaw portion 44c is not caught.

The method of connecting the mandrel shown in FIG.
This is performed by inserting the connection tube 42 into the connection jig 43. If the connection tube 42 is to be pulled out, the tip end 44b of the claw portion 44 expands, and the inside diameter side of the connection tube 42 is hooked, so that the connection tube 42 cannot be pulled out.

In the method of connecting the mandrel shown in FIG. 4, the tip 43a of the connection jig 43 is pressed by the water pressure when the mandrel is pulled out by the water pressure. An effect of being easily performed can also be achieved.

[0036]

As described above, the method for connecting mandrels according to the present invention is very simple and can be performed in a short time. Further, since a hollow connection tube is used and the rubber hose is cut at this portion, a cavity for applying water pressure is secured at the same time as the cutting. Further, since it is not necessary to cut the mandrel main body, the mandrel can be used any number of times simply by replacing the connection tube.

In addition, there is no step at the connecting portion,
Since the position can be easily known by using a magnetic sensor for cutting, a skilled worker is not required, and a rubber hose having an accurate length can be obtained.

By employing the connecting method of the present invention, the manufacturing cost can be reduced to about 3/5 as compared with a case where a rubber hose is manufactured by a conventional connecting method.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for connecting a mandrel according to claim 1;

FIG. 2 is a diagram illustrating a step of pulling out a mandrel connected by a mandrel connection method of the present invention from a rubber hose after vulcanization.

FIG. 3 is an explanatory view of a method for connecting a mandrel according to claim 2;

FIG. 4 is an explanatory view of a method for connecting a mandrel according to claim 3;

FIG. 5 is an explanatory view of a conventional method of connecting a mandrel.

FIG. 6 is an explanatory view of a conventional mandrel connection method.

FIG. 7 is an explanatory view of a conventional method for connecting mandrels.

FIG. 8 is a view illustrating a step of pulling out a mandrel from a rubber hose after vulcanization.

[Explanation of symbols]

 1, 31, 41 Mandrel 2, 32, 42 Connection tube 3, 33, 43 Connecting jig 4 Groove 34 Male thread 44 Claw

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 65/00-65/82 B29C 33/00-33/76 B29C 45/00-45/84 B29C 53/00-53 / 84

Claims (3)

(57) [Claims] (A) having an outer diameter substantially equal to the inner diameter of a connecting tube having an outer diameter equal to the outer diameter of the mandrel;
A step of screwing a connection jig having a smooth surface or a groove on the outer periphery to an end of the mandrel or attaching the connection jig by injection molding; and (b) applying an adhesive to the outer periphery of the connection jig, and then connecting the connection jig. A method for connecting a mandrel, comprising a step of inserting a tube. 2. A connecting jig in which a male thread portion having an outer diameter slightly larger than the inner diameter of a connection tube having an outer diameter equal to the outer diameter of a mandrel is formed on a part or the whole of the surface. And attaching the connection tube to the end of the mandrel by screwing or injection molding, and (b) press-fitting the connection tube into the connection jig. 3. A claw which can be inserted into the inner diameter side of a connection tube having an outer diameter equal to the outer diameter of the mandrel, and which bites into the inner diameter side of the connection tube when trying to pull out the inserted connection tube. A step of attaching a connecting jig having a portion formed therein and easily connecting by simply inserting the connecting tube to the end of the mandrel by screwing or injection molding; and (b) inserting the connecting tube into the connecting jig. A method for connecting a mandrel, comprising the steps of: