JPS5910005B2 - Continuous manufacturing method and manufacturing device for multi-product plastic-coated wires - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 10 The present invention relates to a new method for manufacturing plastic-coated electric wires and a manufacturing device with a novel structure for carrying out the method.

Plastic-coated wires are normally manufactured using a series of manufacturing equipment and 15 steps, mainly consisting of a plastic extruder, but due to its nature, plastic extrusion is unsuitable for small rod production. The only way to reduce production costs has been to manufacture a single product continuously and without interruption for long periods of time.

The reason why the 20 plastics extrusion operation is unsuitable for small rod production is due to the following properties.

(1) As the work is high temperature and requires precise temperature control of cylinders, screws, heads, ties, etc., it takes a lot of heat energy and 25 hours to generate residual heat before starting the machine. After the start of operation, it is inevitable that a large amount of material will be lost as adjustment loss until the temperature conditions stabilize. (2) Once the machine is stopped, residual plastics in each part of the extruder will be thermally degraded due to residual heat in each part of the extruder.
It cannot withstand reuse due to thermal decomposition, etc.

Also, depending on the material, it may be necessary to disassemble and clean the machine, consuming a long time, in order to remove deteriorated or decomposed material every time the machine is stopped. (3) Even when the system is restarted after it has been stopped, it is unavoidable that losses in deflection adjustment, losses due to temperature stabilization, and material losses due to the flow of degraded materials and foreign matter left during disassembly and cleaning are unavoidable.

(4) When changing materials or colors without stopping the machine, mixed materials and colors double the amount of residual material in the machine, resulting in a large amount of material loss, and stagnation in the head and other parts. Materials used may spill out unexpectedly and become contaminated, causing defective products.

As mentioned above, extrusion operations involve large time losses and material losses due to machine stoppages after the start of operation, and have been considered unsuitable for small rod production. The average loss time per stop of an extruder with a cylinder inner diameter of 50 mm and 65 mm is 30 to 40 minutes, and the material loss is 3 kg to 41 <g for PVC material. Despite the above, in the following cases, the machine must be stopped during plastic extrusion coating work.

(1) When it is necessary to change the plastic material (
disassembly and cleaning).

(2) When changing the hue of plastic materials (
disassembly and cleaning).

(3) When changing the outer diameter of the coating to a larger width (disassemble and clean the head to replace the die).

(4) When changing the coating shape (solid extrusion, hollow extrusion, round coating, square coating, single-core extrusion, multi-core extrusion, etc.) (disassemble and clean the head to change the die).

(5) When changing the outer diameter of the conductor, (nipple type)
Disassembly and cleaning of the head for changing) When changing the core outer diameter, (
(6) When the conductor material changes significantly, (hard alloy wire,
annealed copper wire, aluminum wire, copper-clad steel wire, etc.) (replacement of feeding device set).

As mentioned above, the manufacturing of plastic-coated wires is completely unsuitable for small rod production due to the nature of the extrusion process and equipment, and the best way to reduce costs is to mass produce large rods. it is obvious.

Despite this, recent rapid technological innovations have had a major impact on the needs of society, ushering in an era of so-called diversification. The product lifespan of various electrical devices is short, and due to the polarization phenomenon, high-end high-performance devices and low-grade consumer-oriented devices and disposable products coexist, and products with diverse functions are appearing one after another. Therefore, the requirements for various types of plastic-coated wires as wiring materials and for connections between these devices are diverse in terms of performance, structure, appearance, etc., and short delivery times are also a strong priority among users. It is becoming a trend. The structure of electric wires may seem simple at first glance, but the structure of the conductor, the type and structure of the core, the material, performance, hue, and tone of the plastic coated thereon, as well as the size and shape of the overlapping material, are important. , etc., there are hundreds of thousands of combinations. From this combination, equipment manufacturers select the type of plastic-covered wire that is most suitable for each of the tens of thousands of different types of equipment that each company has. There are 2 to 3 types of plastic-coated wires that a general manufacturer of wiring wires actually orders and produces.
It is estimated that it reaches the variety. Electric wire manufacturers try to improve efficiency by combining similar structures, similar colors, and the same materials, and making the rods as large as possible.

However, as mentioned above, due to shortened delivery times, similar wires and wires of the same type are being separated multiple times, there is an increasing trend of emergency additional orders, and interruptions are being made for products with very short delivery times. Notes,
The number of rods produced has not decreased, and it is estimated that the number of changes in production types per company per month has reached over 3,000 times. When extrusion coating such a wide variety of products using about 30 machines, the number of product changeovers per machine per day ranges from 2 to 10 times, with an average of about 5 times. Due to this, the time loss per machine per day is 1 to 5 hours, and the material loss is 6 to 30 kg.
At a wire company of this size, the time lost in switching extruded products in one year is 18,000 hours in total, which is equivalent to 22 hours per year in terms of direct worker hourly wage.
．． It reaches 4 million yen. At the same time, the material loss that occurs is equivalent to 32 million yen per year, converted to 108 tons of PVC. The losses incurred by the wiring wire manufacturer due to the change in product type are not limited to the above-mentioned total loss of 56 million yen/year. In order to deliver products to users without delay in response to high-mix, low-volume production and short delivery times, it is necessary to prepare a huge amount of products in stock in advance. This is because it is impossible to wait for the manufacturing order of a large variety of products, and interrupting production by disrupting the manufacturing schedule will cause confusion in the factory schedule. Also, in order to shorten the delivery period, a large amount of semi-finished product inventory and material inventory is required. For this reason, the bank interest rate increases dramatically, reaching an extremely large amount, and this is also a loss due to the switching of extruded products due to high-mix, low-volume production and short delivery times. In addition, warehouse costs and salaries of management personnel are also losses due to the increase in inventory items. Increased costs due to unavoidable out-of-order notes to meet delivery deadlines, increases in machinery and buildings, and increases in personnel costs are all losses due to product switching. It is estimated that the amount per company will reach several hundred million yen.As mentioned above, the recent diversification trend driven by social needs has brought about an era of high-mix, low-volume production and short delivery times for the electric wire business, and plastic-coated In the case of electric wires, if you rely on conventional manufacturing methods and equipment,
The enormous losses caused by frequent product changeovers during work are becoming an important problem not only for some electric wire manufacturers but also for the electric wire business as a whole.

The present invention provides a new manufacturing method and equipment for the extrusion work of plastic-covered electric wires, thereby eliminating most of the number of times of product changeover during the work, and thereby eliminating the huge loss of products. The aim is to prevent this and achieve significant cost reductions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before explaining one embodiment of the present invention with reference to the drawings, the principle of the present invention will be explained in detail below.

In an application filed on the same date, the applicant of the present invention has disclosed that a main extruder is used to continuously extrude an inner layer coating that determines the main performance of a plastic-coated wire, and two sub-extruder units are constructed in combination with the main extruder. This paper proposes a manufacturing method and an apparatus for manufacturing a wide variety of plastic-coated wires continuously without interruption by extrusion-coating the wires with outer layers that provide different functions alternately depending on the machine.

However, even with this, if the diameter, structure, or material of the conductor or core to be coated changes, the machine must be stopped, disassembled and cleaned, parts replaced, and re-extruded. It is impossible to apply it to all types of mass-produced products, and it is necessary to select the same or similar conductors or cores from the types produced for one month or several months and construct a combination rod. It was hot. By carrying out the present invention in combination with the proposed manufacturing method and its manufacturing equipment, almost all types of plastic-coated wires can be manufactured without stopping or with very short interruptions, without disassembling the machine, and without having to disassemble the parts. It is an object of the present invention to provide a manufacturing method and a manufacturing device that enable continuous production without replacement. That is, the present invention relates to a manufacturing method and an apparatus for manufacturing the same, which makes it possible to manufacture linear bodies such as conductors or cores having different outer diameters in a continuous operation. During extrusion work, the parts inside the head are replaced by replacing the nipple to guide the wire to keep the wire in the center of the forming hole of the die and prevent uneven thickness, and by replacing the die to form the outer diameter. be.

In the conventional structure, there was no other way than to disassemble the head, cut the wire, and replace it. For this purpose, it is necessary to clean the inner wall of the head, the inner wall of the die, the nipple holder, etc., which wastes a lot of time, and during this time, the plastic material inside the cylinder of the extruder main body also has to be wasted. The die can accommodate changes in the outer diameter over a relatively wide range without having to be replaced, and the structure allows the die attachment to be changed from outside the head, and in some cases, the die can also be split. By adopting a die structure or the like, it is easily possible to eliminate the need to disassemble the head and furthermore to make it unnecessary to cut the linear body.

However, in the case of nipples, if the guide hole and the outer diameter of the wire body do not match, uneven thickness will occur, and plastic material will flow back into the nipple and the pressure will cause the wire to break, so the nipple must be replaced. Without this, it would be impossible to accommodate a wide variety of conductors.

Also, due to its structure, it is completely impossible to replace it from the outside or to make it into a split mold. However, if it is possible to draw the tip of the nipple by operating the nipple from the outside, it becomes possible to reduce the hole diameter of the nipple in accordance with the outer diameter of the conductor or core. The present invention has been made based on this principle. Since this is a drawing process, the nipple hole diameter is only reduced in size, and is an irreversible adjustment. Therefore, in continuous production of a wide variety of products, the diameter of the conductor or core is gradually reduced from large to thin, and the nipple is drawn to fit the diameter. It is impossible to do so. As described above, the method for manufacturing multi-product plastic electric wires according to the present invention begins by appropriately selecting and combining unit linear bodies of conductors or cores.

In other words, by selecting unit linear bodies that are as close as possible to each other and sequentially connecting and connecting them in order of thickness, a long linear body can be constructed, and the coating can be processed starting from the one with the largest diameter. This is one of the elements of the present invention. However, this connection does not necessarily have to be completed in advance, and may be carried out by extrusion coating starting from the largest diameter, and then sequentially connecting the thinner ones. The element can be used to draw the nipple tip during an extrusion coating operation without stopping the operation, or by stopping or slowing down the extrusion equipment for a very short time, without disassembling the extruder head, and without replacing the nipple in the head. The purpose is to reduce and adjust the diameter to match the outer diameter of the linear body passing through the inner diameter of the linear body guide hole.

FIG. 1 is a sectional view showing the structure of a head that allows drawing of the tip of the nibble by operation from outside the head. A feature of this structure is that a protrusion made of an extremely hard material is provided on the inner wall of the die or die holder, and the protrusion may be of a type in which the height of the protrusion can be adjusted or of a type in which the height of the protrusion is fixed. Another feature of this structure is that the tip of the nipple can be rotated while being brought into pressurized contact with the protrusion by external operation. Of course, the pressing force in this case is the pressure necessary for drawing. In addition, this pressure may be applied by the protruding body in the case of the above-described protruding height adjustable type. In FIG. 1, 1 is the head main body, and 2 is the nipple holder-supporting tubular body.

2 supports a nipple holder 3 so as to be rotatable and movable back and forth.

For this purpose, a ball bearing 9 is provided between the two,
Furthermore, the contact area between the two is filled with a high temperature resistant lubricant such as fine molybdenum disulfide powder. A nipple 4 is held by a nipple holder 3, rotates together, and moves back and forth together.

In addition, in conventional extruders, nipples were made of wear-resistant metal and given extremely high hardness, but in order to implement the present invention, we sacrificed hardness in order to give extreme malleability and improve drawing workability. It is distinctive in that it is The tongue 12, the tightening bolt openings 1 and 1V, and the thrust bearing 10 keep the nipple holder 3 and the nipple 4 in a freely rotatable state.
It is a mechanism that can be moved back and forth and brought into pressure contact with the protrusion 8. V indicates sheaves 13 and 13' for transmitting power for rotating the nipple holder 13 and the nipple 4. Reference numeral 5 denotes a die for molding the outside diameter of the plastic coating, and in this embodiment, the exit side of the molding hole is provided with a relatively large radius on the exit side to widen the outside diameter of the finished coated wire. It is designed to handle the continuous production of a wide variety of electric wires.

6 is a die holder, and 7 and 7' are thickness unevenness adjustment bolts.

Reference numerals 8 and 8' denote protrusions for drawing, which protrude from the inner wall of the die 5 and whose height is adjusted by the screw holes in the die hole.

The tip is located at a position where it can press the tip of the nipple. In this embodiment, the protrusions 8 are provided on the inner wall of the die 5, but depending on the structure of the die 5, they may be provided on the inner wall of the die holder 6. 16 is molten plastic, and after extrusion, a coating 15 is formed around the conductor or core 14.

Reference numeral 17 denotes a gap between the nipple holder 13 and its supporting tubular body 2, which is filled with a heat-resistant lubricant such as molybdenum disulfide.

Because of this structure of the extrusion head used in carrying out the present invention, sufficient pressure can be applied to the tip of the nipple 4 by the protrusions 8, 8' even during extrusion operation by external operation. or with sufficient pressure, press the tip of the nipple against the protruding body 8,
8', the nipple 4 is rotated, thereby melting the tip of the nipple, compressing and reducing the inner diameter of the guide hole 4a in the tip of the nipple to a desired inner diameter, and reducing the inner diameter of the guide hole 4a in the tip of the nipple. Even if the inner diameter of the nipple becomes smaller, it is maintained at the center of the die forming hole by the reduced guide hole 4a to prevent uneven thickness, and the molten plastic enters into the nipple guide hole 4a and the pressure increases. This makes it possible to prevent the shaped body from breaking.

FIG. 2 is a sectional view of the protrusions 8, 8' in FIG. 1 at their installation positions, clearly showing the relative positional relationship with the tip of the nipple.

FIG. 3 is a cross-sectional view of the case where the protrusions 8, 8' of fixed protrusion height are provided. The protrusions 8, 8' are made of a material with extremely high hardness, and the smoother the protrusions, the better the drawing workability. If the diameter of the tip of the nipple is large and a large resistance occurs during drawing, it is more effective to provide a rotatable hard spherical body at the tip of the projections 8, 8'. As mentioned above, the tip of the nipple is made of a material with relatively low hardness in order to provide ductility.

Therefore, when working continuously for a long time, the inside of the guide hole will wear unevenly due to the pressure of the molten plastic, and there is a risk that the wire will dig into this worn part and cause damage or breakage. be. In order to prevent this, it is desirable to always rotate the nipple holder from the outside at a low speed, that is, to carry out the extrusion operation while rotating the tip of the nipple. As a result, the guide hole 4a at the tip of the nipple can always maintain a perfect circular shape. If the guide hole 4a is enlarged due to wear and the extrusion operation is about to be hindered, use the external operation described above to reduce the inner diameter of the guide hole 4a by drawing while continuing the extrusion operation. It only needs to be reduced in size, and like the nipple 4 formed of a hard material in this way, it can withstand long-term use.

As described above, the method for producing a wide variety of plastic-coated wires according to the present invention can extrude a large number of coated wires with different conductor or core diameters and slightly different coating outer diameters without stopping the extrusion operation or reducing the extrusion speed to a low speed. This makes it possible to perform production while changing product types without stopping or with only an extremely short stoppage. As mentioned at the beginning, compared to conventional multi-product extrusion work that relies on product switching, this reduces time loss, reduces material loss, increases the ability to respond to high-mix, low-volume production and short delivery times, and increases product inventory. Its contribution is immeasurable, such as the reduction in interest costs and management costs due to the reduction in semi-finished product inventory and material inventory charges. Matasui Oshide Greeting 1
If you combine a manufacturing method that combines a stand and two sub-extruders and use the sub-extruders alternately to continuously produce a wide variety of covered wires, you can continuously produce almost all kinds of plastic-covered wires. This makes it possible to perform non-stop production, and the effects described above can achieve even greater results. The internal structure of the extrusion head for carrying out the above-mentioned manufacturing method, in which the tip of the nipple is drawn by an external operation, is as shown in FIGS. 1, 2, and 3.
Although various structures other than the one shown in the figure can be considered, this one has the following advantages: it has the simplest structure, is easy to disassemble and assemble, and is also extremely easy to operate from the outside. It is easy to implement and extremely useful.

Another notable advantage is that the structure allows the nipple holder and the nipple to be constantly rotated at low speed during extrusion work, so the wear of the guide hole at the tip of the nipple is uniform and the tool can always maintain a circular shape. Therefore, the life of the nipple is long, and the thickness unevenness of the extrusion coating can be easily adjusted and high quality can be maintained. It is believed that the plastic coating apparatus according to the present invention as described in Section 7 will make an extremely large contribution to the industry due to these advantages. As a modification or application of the manufacturing apparatus according to the present invention, it is possible to omit the protrusion altogether or to provide a structure in which a very small ring-shaped protrusion is provided around the inner wall of the die. In this case, the drawing of the tip of the nipple is carried out by press-fitting the tip of the nipple into the tapered part of the die with the above-mentioned structure with relatively strong pressure, or by rotating the nipple and press-fitting it for a relatively long time. do. When creating such an applied structure, it is necessary to consider the use of cemented carbide, die steel, etc. in order to make the die a strong structure that can withstand strong pressure and to enhance wear resistance. In the case of such an applied structure, although there is an advantage that the structure and operation are easy, it is necessary to temporarily stop the extrusion operation and perform the drawing process, albeit for a short time. This is because the tapered part of the die is sealed during drawing, making it impossible to extrude the molten plastic. Furthermore, the manufacturing method and device according to the present invention can be said to be a new manufacturing method and device that greatly reduces the manual work required to change types as a first step toward unmanning a plastic coated wire manufacturing factory. From this point of view as well, it is considered to have great industrial value.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view for explaining an embodiment of the manufacturing method and apparatus for manufacturing the same according to the present invention, and FIGS. 2 and 3 are cross-sectional views of a protruding body portion. DESCRIPTION OF SYMBOLS 1...Head body, 3...Nipple holder 1, 4...Nipple, 5...Die, 8, 81...Protrusion body, 14 ······conductor,
15...Plastic coating, 16...
・Melting plastics.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a plastics-coated electric wire in which the outer periphery of a long linear conductor is continuously covered with plastics using a plastics extruder, in which a wire having a large diameter is placed inside the head of the extruder. The wire diameter of the linear conductor becomes thinner while introducing the long linear conductor connected sequentially from thinner to thinner one and leading it out from the guide hole of the nipple for guiding the linear conductor provided at the end of the head. Accordingly, there is provided a continuous manufacturing method for a wide variety of plastic-coated electric wires, characterized in that plastic coating is applied to the outer periphery of the conductor while adjusting the tip of the nipple using a plastic deformation processing means provided inside the head. 2. An extrusion head of a plastics extruder having a molten plastic flow path, which is rotatably arranged and supported within the flow path of the head, and has a linear conductor guide hole formed at its tip and a plastic extrusion head. A conical nipple body that can be deformed; a long linear conductor that is introduced from one end of the nipple body and led out from a guide hole at the other end and connected in order from one with a thicker wire diameter to one with a thinner diameter; a plastic molding die that covers the conical end of the nipple main body with a predetermined gap, has a hole in communication with the flow path and is coaxial with the guide hole, and is attached to the head end; and a predetermined number of protrusions provided at predetermined locations on the molding die, the tip of which is brought into pressure contact with the conical end of the nipple body to plastically deform the tip of the nipple body. Continuous production equipment for coated wires.