JPS598928B2 - Continuous manufacturing equipment for multi-product plastic coated wires - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for continuously manufacturing plastic-coated electric wires.

Plastic-coated electric wires are normally manufactured using a series of manufacturing equipment and processes centered on a plastics extruder, but plastics extrusion is, by its nature, unsuitable for small rod production. Therefore, the only way to reduce production costs has been to manufacture a single product over long periods of time without stopping.

The reasons why plastics extrusion operations are unsuitable for small rod production are due to the following properties.

10(l) Since the work is high temperature and requires precise temperature control of cylinders, screws, heads, dies, etc., it requires a lot of time and thermal energy to generate residual heat before starting the machine, and it is difficult to recycle. After the start of operation, it is inevitable that a large amount of material will be lost as adjustment loss 15 until the temperature conditions are stabilized.

(2) Once the machine is stopped, the residual plastics in each part of the extruder will undergo thermal deterioration, thermal decomposition, etc. due to the residual heat of each part of the machine, and cannot be reused.

Also, depending on the material, deteriorated or decomposed materials may be removed each time the system is stopped.
In order to remove zero, it becomes necessary to disassemble and clean the machine, which takes a long time. (3) Deflection adjustment loss occurs even when restarting after a temporary stop.

25 occurrences such as loss due to temperature stabilization and material loss due to deterioration and foreign matter remaining during disassembly and cleaning are unavoidable. (4) When changing materials or colors without stopping the machine, mixed materials and mixed colors double the amount of residual material in the machine, resulting in a large amount of material loss, and the previous time stagnation in the head and other parts. Materials used may leak out at unexpected times 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 3530 to 40 minutes, and the material loss is 3 in 9 to 4 layers in the case of 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 wider width, (Disassembly and cleaning of the head for die replacement) (4) Coating When changing the 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, (Head disassembly and cleaning due to nipple change) When changing the core outer diameter (same as above) (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 production of plastic-coated wires is completely unsuitable for small rod production due to the nature of extrusion work and equipment, and it is difficult to reduce costs. It is clear that the best way to achieve this is to adopt a large rod mass production system.

And that too! However, recent rapid technological innovations have had a major impact on the needs of society, and we are now entering an era of so-called diversification. Even in various electrical equipment, the product lifespan is short, and due to the polarization phenomenon, high-end high-performance equipment and low-class consumer-oriented equipment and disposable products coexist, and products with a variety of diverse functions are appearing one after another! be. Therefore, the requirements for various plastic-coated wires as wiring materials and for connections between devices are based on their performance,
There is a wide variety of structures, appearances, etc., and short delivery times are becoming a strong need for users! be. The structure of electric wires seems simple at first glance, but there are various factors such as the type and structure of the conductor and core, the material, performance, hue, and tone of the plastic coated on it, as well as the size, shape, and size of the coating. There are hundreds of thousands of combinations. From this combination, equipment manufacturers select the type of plastic-coated wire that is most suitable for each of the tens of thousands of different types of equipment that each company has. There are two types of plastic-coated wires that a general manufacturer of electric wires actually orders and produces.
It is estimated that there are as many as 30,000 varieties. Electric wire manufacturers are trying to improve efficiency by integrating similar materials with similar structures and colors to make the rods as large as possible! Produce.

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. As a result, the time loss per machine per day is 1 to 5 hours, and the material loss is 6 to 30 odor. At a wire company of this size, the annual loss in switching between extruded products is a total of 18,000 hours, which translates to direct worker hourly wages of 240 hours per year.
Reach 00,000 yen. At the same time, the material loss that occurs is 10% per year.
8t0n, equivalent to 32 million yen in PvC amount. The losses incurred by the wiring wire manufacturer due to product change are not limited to the above-mentioned total loss of 56 million yen/year.

In order to respond to high-mix, low-volume production and short delivery times and to deliver products to users without delay, it is necessary to prepare a huge amount of inventory 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. Furthermore, in order to shorten the delivery period, a large amount of semi-finished product inventory and material inventory is also 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 management staff salaries for this increase in inventory are losses as well. Increased costs due to unavoidable out-of-order notes to meet delivery deadlines, addition of machinery and buildings (to compensate for changeover time losses) to meet delivery deadlines, and increased labor costs are all losses caused by product switching. . It is estimated that the total losses from these operations amount to hundreds of millions of yen per company. 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 in the case of plastic-covered electric wires, traditional manufacturing methods and manufacturing equipment are no longer relied on. Therefore, the enormous losses caused by frequent product changeovers during work become an important problem not only for some electric wire manufacturers but also for the electric wire business as a whole.
be. The present invention provides a new manufacturing method and equipment for the extrusion work of plastic-coated electric wires, thereby eliminating most of the number of times the product type must be changed during the work, and thereby eliminating the huge losses caused by the process. The aim is to prevent this and achieve significant cost reductions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The manufacturing method and apparatus thereof according to the present invention will be explained in detail below with reference to the drawings.

The basis of the present invention lies in the conversion of the design concept of plastic-coated electric wires, and therefore starts with improving the structure of plastic-coated electric wires. Figure 6 is a cross-sectional view showing the structure of a conventional plastic-coated electric wire. 25 is a conductor and 26 is a plastic coating.

This is an example of the structure, and the conductor 25 may be a single wire, or may be a stranded conductor with 7, 12, or 19 wires, or may be a composite stranded wire of steel wire and aluminum wire. Moreover, instead of a conductor, a core formed by twisting or gathering various insulated core wires may be used. Furthermore, various tapes may be wound around this core. The coating 26 may be an insulating coating or a protective coating.

Further, the coating may be a solid type coating that completely adheres to the conductor or core, or it may be a non-solid type coating that is simply covered with a tubular hollow pipe. The coating 26 has insulation performance, abrasion resistance, heat resistance, low temperature resistance, heat deterioration characteristics, photostability, flexibility, tensile strength, impact resistance, and the intended use of the wire according to the needs of the user. In the case of identification and exposed wiring, more than a dozen different hues and tones are used to harmonize with the surrounding colors. The combination of the above-mentioned changes results in the use of an almost infinite number of plastic materials, which, on the other hand, is a source of inefficiency in extrusion coating operations. FIG. 7 is a cross-sectional view of an electric wire showing the electric wire design concept and structure that are the basis of manufacturing the plastic-coated electric wire according to the present invention.

Note that the same parts are indicated by the same reference numerals. Reference numeral 25 designates a conductor, core, etc. exactly the same as in FIG.

30 and 31 are plastic coatings of different types or colors, respectively.

The electric wire illustrated in FIG. 7 exhibits exactly the same performance or appearance as the electric wire illustrated in FIG. 6, and its uses are also exactly the same.

That is, the coatings 30 and 31 are both knobs. This serves as the covering 26.

Furthermore, the outer coating 31 is characterized by an extremely thin wall thickness compared to the inner coating 30. The above-mentioned change in the design concept of electric wires is based on these two points.In other words, the conventional idea of achieving the desired function with a single plastic material was changed to two types: a thick inner layer coating and a thin outer layer coating. The novel wire manufacturing method and device according to the present invention are designed to have a composite structure with a wire covering, and to combine the functions of two different types of plastics to perform the same functions as conventionally designed wire coverings. There is a basis for creating it. Conventionally, many electric wires with composite structures have been provided. That is, wires coated with a thin film for different colors, wires coated with a nylon jacket to improve the abrasion resistance of PVC wires, and the like. However, from the time of their design, they were designed with their own complex functions in mind. The composite covered wire shown in Fig. 7, which is the basis of the present invention, was originally the single coated wire shown in Fig. 6, which was generally used or specified, and by changing its design concept, it was possible to create a coated wire that provides the same and equivalent functions. They are designed and manufactured, and they differ in their significance, use, etc. For example, there is no PVC wire with the same function as the nylon jacket PVC wire, but a fire-retardant wire as shown in FIG. 6 is designed to have the structure shown in FIG. 7, and the sheath 30 is formed using fire-spreadable PVC. The sheath 31 is formed using extremely flame-retardant PVC, and it is possible to design an electric wire that has exactly the same function as the structure shown in FIG. 6 as a whole. Cost reduction by reducing the amount of inventory, which is one of the objects of the present invention, can be brought to a considerable effect simply by changing the electric wire design concept as described above.

For example, in several dozens of different colored wires with similar performance,
If all the plastic materials corresponding to the inner layer coating 30 are manufactured in the same color, the material for color change is only used for the thin coating 31 as the outer layer coating, so the amount of material inventory can be greatly reduced. I can do it. Also, in the case of heat-resistant wires,
In many cases, the purpose can be achieved by using a general-purpose plastic for the inner layer and using a heat-resistant material only for the outer layer. By changing the design in this way, we can reduce the usage of expensive heat-resistant materials and use the wire itself! In addition to being able to reduce costs, it is also possible to significantly reduce the inventory of expensive heat-resistant materials, thereby reducing costs. In addition, by stocking semi-finished products that are common to a wide variety of products with the inner layer coating completed, and shipping after applying the outer layer coating according to orders, it is possible to shorten delivery times and reduce the type and amount of semi-finished products in stock. This makes it possible to reduce costs. The effects of the present invention are not limited to this level, and even greater cost reductions can be achieved through the improved manufacturing method of the improved designed product.

1 to 5 show a method and apparatus for continuously manufacturing a wide variety of plastic-coated wires according to the present invention.

Figures 1 and 2 show the structure of the plastics extrusion coating device, Figure 3 shows the structure of the extrusion head, and Figure 4 shows the structure of the extrusion head.
Figure 5 shows the injection amount of molten plastic for outer layer coating,
The structure of the flow control section that controls the direction etc. is shown. In FIG. 1, 1 is a main extruder, 2 and 3 are sub-extruders, and 6 sub-extruders 2 and 3 each have a common head 5, which is the tip of an extrusion head 4 of the main extruder 1. It is arranged so that it is connected to the common head 5 at the tip of the head.

Although this arrangement is symmetrical in the drawing, it is not necessarily limited to this arrangement. One unit may be vertical, one unit may be horizontal, or both units may be arranged at an angle. The tips of both sub-extruders and the common head 5 are connected by hollow tubes 6 and 7, which are molten plastic flow paths. The molten plastic flow path is provided with flow path adjustment sections 8a and 9a for injecting and stopping the injection of molten plastic into the common head 5. In addition, the flow path adjustment parts 8a, 9a are equipped not only with the main pots 8, 9 for injecting and stopping molten plastic, but also with sub-cots 8', 8 and 9', 9. The molten plastic is allowed to overflow at the front and back, and the overflow can be stopped or adjusted. Using the main extruder 1 and the sub-extruders 2 and 3 arranged in this manner, a plastic-coated electric wire having a composite coating as shown in FIG. 7 is manufactured to carry out the manufacturing method according to the present invention.

The conductor or core 10 is the main extruder head 4 and its tip, and passes through the common head 5 of the sub-extruders 2,3. At this time, the main extruder 1 is supplied with a plastics material (FIG. 3, 20) which determines the basic performance of the electric wire, and the plastic material 10 is coated at the tip of the extrusion head. This is the inner layer coating of the electric wire, and this inner layer coating operation continues until the planned extrusion coating of various types of electric wires is completed. When applying the inner layer coating at the tip of the head, at the same time, an outer layer coating is applied around the inner layer coating. The outer layer coating material is a material that is combined with the inner layer coating to provide the desired function, and two sub-extruders 2 and 3 are used to continuously extrude various outer layer coating materials alternately. To manufacture a wide variety of plastic-coated electric wires while providing various desired functions in combination with a common inner layer coating. The manufacturing method according to the present invention is characterized in that when switching the product type, the outer coating is switched at an accurate predetermined length with as little switching loss as possible. The procedure will be explained below with reference to FIG. First, a first type of outer layer material 21 is extruded into the common head 5 using the sub-extruder 2.

In this case, the main pot 8 of the flow control section 8a is open, and the sub pot 8 is open.
′, 8〃 are set as closed and 1-. Therefore, the material discharge hole 23,
No overflow occurs from 23'. This state is the fourth
It is shown in the figure. The material 21 for the outer layer which has passed through the plastic channel hollow tube 6 is injected into an annular material reservoir 15 in the common head 5 by means of a nozzle 17 at the tip of the hollow tube 6. These conditions are illustrated in FIG. 3, a sectional view of the head of the main extruder 1 and the common head. During this time, in order to help fill the annular material reservoir 15 with the plastic material 21, the main pot 9 in the flow control section 9a of the sub-extruder 3 is closed.
Deputy Kotuku 9〃 is open. The air in the common head 5 is discharged to the outside through the material discharge hole 24' to help the material 21 fill the head, i.e., the annular material reservoir 15, completely and smoothly. Furthermore, it fills all the material passages up to the flow control section 9a of the sub-extruder 3, passes through the sub-cottle 9, and is discharged to the outside as an overflow 21' from the discharge hole 24'. At this point, when the sub-cock 9 is throttled so that the flow rate of the overflow 21' becomes extremely small, the internal pressure of the plastic material 21 increases in all parts of the flow path, and the inner pressure of the annular material reservoir 15 increases. Through the annular slit 16 of the common head 5
Inside, the outer coating material 20 is extruded around the inner coating material 20. This extrusion device is located near the tip of the nipple in the drawing, and the materials 20 and 21, which are concentric at this point, are almost exactly as they are! The cross section is reduced to a similar shape, the outer shape is adjusted with a die 14, and the wire body 10, which is a conductor or core, is coated and formed into a composite coated electric wire 11. During the above procedure, a very small amount of material 21 is removed from the material discharge hole 24'.
The reason why this is carried out while overflowing 21' is due to the following two reasons, which are also important features of the present manufacturing method. (1) Stopping during operation Material will accumulate in the plastic material flow path on the sub-extruder side, and the material in this area will cause thermal decomposition or thermal deterioration due to the influence of high heat from the head, and the next There is a risk of defective products occurring when switching to the second type.

In some cases, the decomposed and carbonized material may make it impossible to extrude, resulting in work stoppage. (2) Depending on the material, the material may not flow normally inside the annular material reservoir 15, and the flow may be particularly poor in the portion opposite to the injection side.

By opening the pot 9 slightly to allow overflow, the material can easily flow to the opposite part of the injection side, and the material can be extruded uniformly from the annular slit. As described above, the first type of plastic-covered electric wire is manufactured using the main extruder and the sub-extruder.

While manufacturing the first type of electric wire, it is necessary to prepare for manufacturing the second type of electric wire. That is, the second type of plastics 22 is supplied to the sub-extruder 3, the screw 1 is rotated, the screw 9' is opened, and the plastics overflow from the plastics discharge hole 24 to 22' as shown in FIG. Stabilizes the temperature of the screw, cylinder, extrusion tip, plastic flow path, etc. The temperature stabilizer stops the machine and waits for the product to be replaced. The time required for stabilization of temperature conditions is extremely short because the sub-extruder is extremely small, and therefore overflow loss during preparation is only a small experiment. This preparation time is very short, so do not keep the ingredients at high temperature for too long after preparation is complete! Since it is undesirable to wait, it is necessary to estimate the time for completion of manufacturing the first type of electric wire and to determine the start time of the preparatory work so that the preparation for extruding the second type of electric wire is completed at that time. Second
When the preparation for covering the electric wire of the first type is completed and the scheduled length of the electric wire coating of the first type is completed, the operation of the sub-extruder is started, the main socket 9 is opened, and the width socket 9' is closed. The material 22 overflows from the discharge hole 24' in very small quantities via the pot 9. Naturally, the first type material 21 flowing out from the discharge hole 24' stops flowing out due to the pressure of the material 22.
After that, Kotoku 8 is closed.

The material 21 filled in the plastic flow path is material 2.
The extrusion coating is continued on the outer periphery of the inner layer coating while replacing the material 22 at a pressure of 2. During this time, the subcock 8' is opened to start overflowing a very small amount of material, and the subcock 9 is closed. Plastic flow path and annular material reservoir 15
The inner material 21 is consumed and replaced with material 22, completing the coating of the first type electric wire, and starting the outer layer coating of the second type electric wire.

In order to reduce the loss of the material 21 as much as possible when changing the type, the supply of the material 21 to the sub-extruder 2 is stopped shortly before closing the main stock 8, and approximately 1/2 of the cylinder of the sub-extruder 2 is filled with the material 21. By supplying the plastic material for the third type electric wire when the wire is empty and closing the main stock 8 when the material for the third variety reaches the main stock 8, there is almost no loss in switching the material 21. It is possible to make it almost non-existent. Confirmation that the material for the third type electric wire has reached the position of the main pot 8 is confirmed by opening the sub-cot 8 very small and allowing a small amount of the material for the third grade to overflow from the discharge hole 23. You can.

In this way, after the outer layer coating of the second type of electric wire is started, as in the case of the first type, deterioration, decomposition, carbonization, etc. of the material in the stagnation area are prevented, and the material flows throughout the material reservoir 15. In order to make the coating uniform, it is desirable to carry out the coating while opening the secondary pot 8' very slightly and allowing a small amount of the plastic material 22 to continuously overflow from the discharge hole 23'. By the time the sub-extruder 3 completes the outer layer coating of the second type of electric wire, the sub-extruder 2 must complete preparations for the outer layer coating of the third type. The difference from the preparation for manufacturing the second type of electric wire is that the plastic material 21 used in manufacturing the first type of wire remains in the sub-extruder 2. As mentioned earlier, if the material of the third type is supplied when switching from the first type to the second type, there is almost no residual material 21 left, but in this case as well, the material of the 21st type and the third type are supplied. Due to the nature of the extruder, it is unavoidable that mixed materials for different types are left behind. Therefore, preparation for manufacturing the third type involves not only simply supplying the plastic material for the third type to the sub-extruder 2, but also discharging the remaining material 21 and a mixed material with the material for the third type. It is necessary to keep it.

The discharge is completed by opening the auxiliary pot 8 to allow overflow from the discharge port 23, and confirming that the overflowing material has been switched to the third type of plastic material. However, this discharged material is not greater than the initial extrusion operation, and is not much different from the extrusion outlet space required to stabilize the operating temperature conditions, and is extremely small both in terms of time and quantity. This is due to the fact that the sub-extruder is extremely small. Repeat the above procedure and turn the sub-extruders 2 and 3 into 2
By repeatedly using the extruder 1 alternately, various kinds of plastic materials are coated on the inner layer coating by the main extruder 1 to form an outer layer coating,
It becomes possible to manufacture virtually a wide variety of plastic-coated wires continuously and without interruption.

By appropriately selecting similar varieties from among the thousands to tens of thousands of varieties manufactured annually, it can be maintained continuously for 12 hours, 24 hours or more, or even for a week. This makes it possible to manufacture many types of electric wires without stopping.

In Fig. 2, the tip of the head 4 of the main extruder is used as the common head 5 of the sub-extruders 2 and 3, whereas in Fig. 1, the tip of the head of the main extruder is common to the sub-extruders 2 and 3. Head 5'
The figure shows the case where they are arranged separately.

In Fig. 1, the inner layer coating and outer layer coating are applied at the same time, whereas in Fig. 2, the inner layer coating is applied once in the main extruder head 4, and then the outer layer coating is applied by the common head 5'. become. This has the advantage of simplifying the structure of the head and making it easier to operate, but has the disadvantage of poor adhesion between the inner layer and outer layer. Also for outer layer coating.
If the operating temperatures of the plastic material and the outer coating plastic differ widely, a mechanical arrangement as shown in FIG. 2 may be necessary. In the case of the arrangement shown in FIG. 2, the manufacturing procedure is exactly the same. It is desirable that the sub-extruders 2 and 3 be as small as possible, and at present, plastic extruders with a screw diameter of about 18 mm are in practical use, and these can be used as the sub-extruders 2 and 3. However, by selecting a material with higher toughness as the material for the screw and further studying the screw structure, it is thought that it is possible to put into practical use an extruder with a risk of about 15 mm per screw diameter. This is to reduce the material remaining in the screw when changing the outer coating, or the mixed material before and after changing, and also to shorten the preparation time and adjustment time when stopping and restarting operations. . The time loss per stop of a conventional extruder with a screw diameter of 50 mm or 65 mm is 30 minutes to 40 minutes, and the material loss is 3 Kf to 4 Kf using PVC as an example, whereas in the case of a 15 mm diameter extruder, the time loss per stop is 30 minutes to 40 minutes. It is possible to reduce it to about 0.7 Kq in 10 minutes. By applying heat pipes to such small extruders and improving the rapid cooling and rapid heating characteristics, time loss is less than 5 minutes and material loss is 400g.
It is thought that it is not impossible to improve the situation within a short period of time.

In this case, the time can be increased by alternately using two sub-extruders as described above, and by operating the main extruders 8, 9 and sub-extruders 8', 9', 8〃, 9〃 in combination with these extruders. Loss is completely eliminated, and material loss is extremely small due to material cross-circuiting, temperature stabilization, etc. 20 to 30 times per day.
Changing the product type twice will not be a problem in terms of production efficiency. Next, we will consider the possibility of automating this manufacturing method.

(1) Preparatory work from stopping the sub-extruder to restarting it can be automated by standardizing the work for each material.

(2) When restarting the fork extruder, the delay time from the start of one screw rotation until the new material reaches the common head and starts coating can be predicted depending on the type of material and the screw rotation speed. be. (3) The material supply switching procedure between sub-extruders (mainly opening and closing of each main and sub-extruder) can be easily automated.

(4) Since the sub-extruder is small, the diameter of the plastic-coated wire to be manufactured can be finely adjusted with extremely high precision by controlling one rotation of the screw.

(5) Comparatively wide adjustment of the diameter of the covered wire is extremely easy by adjusting the line speed while keeping the screw rotation of the main extruder and sub-extruder constant.

(6) The completion of the scheduled length for each type of wire can be accurately predicted using a measuring machine, and the corresponding procedure for changing the outer layer coating and switching work for winding drums for completed electric wires can be performed by linking the measuring machine and a timer. is easy.

From the state of each factor constituting the present manufacturing method as described above, it can be seen that the type switching in the continuous manufacturing apparatus for multi-type coated wires according to the present invention can be performed with high accuracy with almost no loss, and at the same time, it can be seen that It can be seen that there are no problems in automating work using the existing automation technology.
The computer 1, which is programmed according to the overnight or weekly production schedule, controls each component machine according to the above-mentioned product changeover procedure, and automatically and continuously manufactures more than a dozen types of plastic-coated wires. It can be produced with almost no material loss or time loss.

In this case, the only thing that currently technically requires manual work is the work of connecting and continuously supplying conductors or cores. 1. The apparatus for producing plastic-covered electric wires according to the present invention has one main extruder and two sub-extruders arranged in combination, the sub-extruders are used alternately, and the common head of the two sub-extruders is connected to the common head of each sub-extruder. The two sub-extruders are equipped with a hole for controlling the flow of plastics and a discharge hole for overflow, and these are operated according to a certain procedure. This injection molding machine can be replaced with the same injection molding machine and carried out using exactly the same procedure. In this case, since there is a capacity limit per injection of the injection molding machine, product type switching will be performed more frequently. Therefore, one type of coated wire manufactured by the sub-extruder is divided into a large number of injection rods. The advantages of using an injection molding machine as a sub-extruder are that the amount of injection material per injection can be precisely measured and extruded to the required amount, and the cycle time is short, so the plastics flow There is no need to give much consideration to thermal deterioration or decomposition of the stagnation part in the road.

Therefore, the material loss per changeover becomes even smaller. The disadvantage is that the switching frequency is too high, so manual operation may result in inefficiency.

Therefore, since automated work based on program control is required, equipment costs are likely to be relatively high. However, when the wire diameter of the completed covered wire is very small, there may be an advantage that the frequency of switching is reduced and the accuracy of extruded wire diameter, coating thickness, etc. is improved. This is because injection molding machines have higher mechanical precision and can generate higher pressure than extrusion molding machines. The apparatus for manufacturing plastic-coated electric wires according to the present invention as detailed above solves most of the problems associated with the conventional extrusion method as described in detail at the beginning, and greatly reduces the cost of plastic-coated electric wires. It is clear that the contribution of

According to the present invention, most of the six factors that necessitate machine stoppage and reduce the productivity of high-mix, low-volume, short-term delivery products are resolved as follows. (1) Problems that can be completely solved by the manufacturing method of the present invention: (1) When changing the plastic material; (2) When changing the hue of the plastic material; (2) When producing by sorting and integrating products with approximate outer diameters. (3) When it is necessary to change the outer diameter of the coating, it is possible to change the outer diameter to some extent by improving the shape of the die, adjusting the line speed, and adjusting the rotational speed of the screw of the sub-extruder. deal with.

(4) When changing the outer diameter of the conductor or the outer diameter of the core, it is possible to change the inner diameter of the tip at the nipple end to an approximate outer diameter by using something with a relatively large margin.

3. Partially resolving the problem can be achieved by integrating the same type and type into production rods. (5) In the case of changing the coating shape (6) In the case of changing the conductor material In the above case, extrusion work is stopped and the product is changed in 80
It is estimated that more than % will be eliminated.

The continuous extrusion manufacturing method of a wide variety of plastic-coated wires according to the present invention corresponds to high-mix, low-volume production and short delivery times, eliminates most of the time loss and material loss, and continuously produces a large number of plastic-coated wires per day. It makes it possible to manufacture a variety of electric wires, greatly reducing product inventories, semi-finished products inventories, material inventories, etc. at electric wire manufacturers, which reduces interest rates, reduces management costs, and improves the ability to meet delivery dates. The contribution to increased profits, cost reduction, etc. is enormous. In order to implement this manufacturing method, it is necessary to significantly improve the plastic extruder, which is the central part of the operation. Eliminate extrusion work that relies on a single machine, instead of a single machine, combine one main extruder and two sub-extruders, and use the head end of the main extruder as a common head for the sub-extruders, or The basic structure is that two sub-extruders are connected to a common head that is separately arranged in series with the extruder head.

Alternatively, an injection molding machine may be used as the sub-extruder. Furthermore, as an essential structure of the extruder according to the present invention, a plastics flow control section is provided in each hollow tube section that is a plastics flow path that connects the common head and each sub-extruder.
(1) It is possible to prevent the molten plastic extruded from the sub-extruder in operation from flowing into the sub-extruder which is stopped.

(2) By discharging extremely small amounts of molten blastex from the stopped sub-extruder side, it is possible to prevent deterioration and decomposition of the blastex in areas where it cannot flow during the outer layer coating extrusion process, and to keep it in the common head. assists in uniform flow of plastics.

(3) While one sub-extruder is operating, plastic material is supplied to the other sub-extruder and overflow extrusion is performed to prepare for alternate extrusion.

(4) The remaining plastic from the previous extrusion can be discharged while the other sub-extruder is in operation. It is provided with the following functions.

In Figures 3, 4, and 5, one sub-cock 8, 8, 9', and 9 and one plastic discharge hole are provided in front and behind the main socket 8, 9 to provide these functions. . This does not necessarily have to be a completely similar design;
', 8〃, 9', shi, discharge holes 24, 24' are the main holes 8
, 9 can also be replaced by making them three-sided. The structures shown in Figures 4 and 5 are desirable in order to ensure the smoothness of the plastics flow path and to minimize the amount of accumulated plastics, but some manufacturers, for example, use machines as specialized equipment that handles only polyethylene materials. When designing, the smoothness of the flow path is not much of an issue since viscous resistance is small. If an injection molding machine is used instead of the auxiliary extruder, there is a risk that product types will have to be changed very frequently, so this device should be used for continuous extrusion of a wide variety of extremely thin wires, or the program should be programmed as described above. It is desirable to have an unmanned structure with automatic control.

This is because there is an increased possibility that the operator will make erroneous operations, such as adjusting the amount of material supplied and changing a total of 6 pots in a single period of time. However, since the extrusion apparatus according to the present invention does not have the problem of being difficult to automate as described above, it is preferable that the apparatus having the basic structure of combining two sub-extruders and one main extruder is also combined with a program automatic control device. Rather, it should be considered as the first step towards unmanned electric wire manufacturing factories.

It is believed that the manufacturing method and apparatus according to the present invention have great industrial value from this point as well. In addition to the above, the present invention uses a main extruder as a conventionally known working method and device. There has been a method and apparatus in which one unit and one sub-extruder are combined, and the sub-extruder extrudes an outer layer on the plastic coating extruded by the main extruder. The purpose is to apply colored or colored linear marks for identification.
There has never been any idea or device put into practical use that allows continuous, non-stop application of a wide variety of coatings by alternately using two sub-extruders.

Furthermore, it is possible to minimize the time loss and material loss during product changeover due to the switching operation of multiple units as in the manufacturing apparatus according to the present invention, and to prevent thermal decomposition and deterioration of stagnant material to provide a good quality coating. There are no methods or devices that can guarantee this.

Furthermore, the inner layer is continuously extruded and coated using the main extruder, and the outer layer is coated in various ways using the sub-extruder, resulting in a wide variety of plastic-coated wires with completely different functions due to the composite structure of the inner and outer layers. The idea of continuously manufacturing a wide variety of electric wires by configuring the wires as follows had never been considered before. That is, the manufacturing apparatus according to the present invention can be said to be a novel invention that has not existed in the prior art.

[Brief explanation of the drawing]

1 and 2 are structural explanatory diagrams showing an example of the combined arrangement of a main extruder and a sub-extruder in the method and apparatus for manufacturing multi-product plastic-coated wires according to the present invention, and FIG. 3 shows a main extruder head and a sub-extruder. A cross-sectional view showing the common head of the extruder, Figures 4 and 5 are enlarged cross-sectional views of the main and sub-heads;
The figure is a cross-sectional view of a conventional plastic-coated electric wire, and FIG. 7 is a cross-sectional view of a composite-structure plastic-coated electric wire according to the present invention. DESCRIPTION OF SYMBOLS 1... Main extruder, 2, 3... Sub-extruder, 5... Common head, 8, 9... Main cock, 8a, 9a... Flow control section, 8', 8〃, 9', 9I-- Vice Kotsuku, 1
0...Conductor or core, 12...Nipple holder -
13... Nipple, 15... Annular material reservoir, 16...
・Annular slit, 25...conductor or core, 26...
Plastic coating, 30, 31... Inner layer and outer layer plastic coating.

Claims (1)

[Claims] 1. A long linear body moving at a predetermined speed and a head through which the linear body is passed, and the linear body is coated with plastic when passing through the head. A main plastics extruder for forming plastics, and a plastics disposed at the head tip of the main extruder to coat the outer periphery of the plastics formed on the elongated linear body with a plastics different from the plastics. A continuous production device for multi-product plastic-coated electric wires, which is equipped with two sub-plastic extruders and a control device that alternately operates the sub-extruders. 2. While one of the sub-plastics extruders is in operation, the other is stopped, and a very small amount of plastics flows out from the stopped sub-extruder and also flows into the cylinder of the stopped sub-extruder. 2. The apparatus for continuously manufacturing multi-product plastic-coated electric wires according to claim 1, further comprising an overflow hole for discharging residual plastics.