JP5546738B2 - Extrusion machine die - Google Patents

Description

  The present invention relates to a die of an extrusion molding machine comprising a die body for extruding a resin composition melted in a cylinder, a die attached to an extrusion port of the die body, and a mandrel disposed in the die body. About.

  The covered electric wire includes a core wire made of copper, aluminum, or the like, and a covering portion made of a resin composition such as a synthetic resin that covers the core wire. Such a covered electric wire is manufactured by, for example, an extrusion molding machine.

  The extrusion molding machine includes, for example, at least a screw, a cylinder in which the screw is housed, a heater for heating the inside of the cylinder, and a die (die) attached to the tip of the cylinder. The resin composition constituting the covering portion of the covered electric wire is supplied into the cylinder from the base end portion of the cylinder, melted in the cylinder by the shearing heat from the screw and the heat from the heater, and pushed out to the die.

  The die is a so-called cross head die. The die is an L-shaped cylindrical die body that extrudes the molten resin composition in the cylinder, a base that is attached to the extrusion port of the die body, and a core that is arranged in the die body and passes the core wire of the covered wire inside With money. The molten resin composition in the die body passes between the die and the mandrel, and is extruded onto the outer peripheral surface of the core wire that moves at a constant speed along the longitudinal direction, thereby covering the core wire. As described above, the covered electric wire is manufactured.

  By the way, when a covered electric wire is manufactured continuously for a long time, so-called discoloration may occur on the contact surface of the base or the core with the resin composition. An eye-gear is a deteriorated product of a resin composition, a part of a compounding agent (such as a filler), an oxide thereof, or a decomposition product thereof. When the spear occurs and adheres to the contact surface, a concave groove-like streak is formed on the outer surface of the molded product, that is, the covered electric wire. Further, the spear becomes larger with time and peels off from the contact surface and adheres to the outer surface of the covered electric wire. For this reason, it is necessary to remove the generated spears as needed, and it is difficult to continuously manufacture the covered electric wire.

In order to solve such a problem, various dies have been proposed (see, for example, Patent Document 1). In the die described in Patent Document 1, a contact surface with a base or a resin composition of a mandrel is sequentially subjected to a blast treatment, a hard chrome plating treatment, and a chromium nitride treatment. By setting it as such a contact surface, the lubricity of this contact surface is improved and generation | occurrence | production of an eye scum is prevented. In addition to improving the structure of the die in this way, there are also those that prevent generation of eyes by improving the composition of the resin composition or applying ultrasonic vibration to the die. .
JP 2005-246817 A

  However, in the die described in Patent Document 1, the contact surface with the base and the resin composition of the mandrel is subjected to blasting, hard chrome plating, and chromium nitride treatment in order to improve lubricity, Depending on the type of the resin composition, there is a problem that the eyes may be generated and it is difficult to cope with various resin compositions. For example, when the resin composition is a polyolefin-based synthetic resin containing a high proportion of filler, it is difficult to prevent the occurrence of eyes.

  Further, the method for improving the composition of the resin composition has a problem that it is difficult to cope with various resin compositions because it is necessary to examine the composition of each resin composition. In addition, the method of applying vibration by ultrasonic waves to the die can be applied to various resin compositions, but it is difficult to reliably propagate the vibration to the entire contact surface of the base and the mandrel. Is a difficult situation.

  The present invention aims to solve such problems. That is, an object of the present invention is to provide a die for an extruder that can improve the lubricity of the contact surface with the resin composition and can reliably prevent the occurrence of creaking.

In order to solve the above problems and achieve the object, the invention described in claim 1 includes a die body for extruding a resin composition melted in a cylinder, a die attached to an extrusion port of the die body, In a die of an extrusion molding machine provided with a mandrel disposed in a die body, the die is composed of a sintered body having continuous pores that can be impregnated with a lubricant, and the tip of the mandrel Is composed of a sintered body having continuous pores that can be impregnated with a lubricant, and the Vickers hardness HV of the sintered body is 680 or more as a minimum value. It is the die | dye of the extrusion molding machine characterized by being comprised with the iron-type sintered alloy containing% .

The invention described in claim 2 is the die for an extruder according to claim 1 , wherein the continuous pores have a diameter of 1 to 50 μm.

According to a third aspect of the present invention, there is provided the die of the extrusion molding machine according to the first or second aspect , wherein a hole through which the lubricant supplied to the die passes is penetrated through the die body. A linear portion having a tip opened toward the outer peripheral surface of the base, and an annular portion that is connected to the linear portion and provided in a concave shape from the inner surface of the die body over the entire circumferential direction of the die body. This is a die of an extruder.

According to a fourth aspect of the present invention, in the die of the extrusion molding machine according to any one of the first to third aspects, the second hole portion through which the lubricant is passed is the main body of the mandrel. A die for an extrusion molding machine, characterized in that the die is provided so as to penetrate the portion and have its tip opened toward the back surface of the tip of the mandrel.

The invention described in claim 5 is the die of the extrusion molding machine described in any one of claims 1 to 4 , wherein the lubricant has a kinematic viscosity at 25 ° C. of ²⁰ to 1000 mm ² / s. It is the die | dye of the extrusion molding machine characterized by being comprised with a certain lubricating liquid.

The invention described in claim 6 is the die for an extruder according to claim 5 , wherein the lubricating liquid is made of silicone oil.

The invention described in claim 7 is the die for an extruder according to claim 5 , wherein the lubricating liquid is composed of a polyoxyalkylene compound. .

  According to the invention described in claim 1, since the die is composed of a sintered body having continuous pores that can be impregnated with a lubricant, the die contacts the resin surface of the die from the continuous pores. Lubricant is constantly supplied to improve the lubricity of the contact surface, prevent the occurrence of spears on the die, improve the surface quality of the product, and operate the extrusion machine continuously for a long time. it can. Moreover, by improving the lubricity of the contact surface, the extrusion speed of the extruder can be set high, and various resin compositions from low viscosity to high viscosity can be handled.

Further, since the tip of the mandrel is composed of a sintered body having continuous pores that can be impregnated with the lubricant, the lubricant is provided on the contact surface between the continuous pores and the resin composition at the tip of the mandrel. Is constantly supplied to improve the lubricity of the contact surface, prevent the occurrence of spears at the tip, improve the surface quality of the product, and operate the extruder continuously for a long time. it can. Moreover, by improving the lubricity of the contact surface, the extrusion speed of the extruder can be set high, and various resin compositions from low viscosity to high viscosity can be handled.

In addition, since the sintered body has a Vickers hardness HV of 680 or more, the sintered body is not damaged by the pressure applied during operation of the extrusion molding machine, and the base and the core have sufficient strength. be able to.

In addition , since the sintered body is made of an iron-based sintered alloy containing 10 to 30% copper, the Vickers hardness HV can be easily set to 680 or more, and a die or core having sufficient strength. It can be gold.

According to the second aspect of the present invention, since the diameter of the continuous pores is 1 to 50 μm, the lubricant can be smoothly passed through the continuous pores while maintaining the strength of the sintered body.

According to the third aspect of the present invention, the hole portion extends through the die body and the tip of the hole portion opens toward the outer peripheral surface of the die, and the straight portion extends to the entire circumferential direction of the die body. Since the annular portion provided in the concave from the inner surface of the die body is provided, the lubricant can be evenly supplied from the entire circumferential direction of the die to the entire inside of the die. Furthermore, since the lubricant can be constantly supplied to the die even when the extruder is in operation, the lubricant is not exhausted from the die and the extruder is not stopped to supply the lubricant. It can be operated continuously for a long time.

According to the invention described in claim 4 , since the second hole portion is provided so as to penetrate the main body portion of the mandrel and the tip thereof is opened toward the back surface of the tip portion of the mandrel, the lubricant Can be reliably supplied to the tip of the mandrel. Furthermore, since the lubricant can be supplied to the tip of the mandrel at all times even when the extrusion molding machine is in operation, the lubricant is not exhausted from the tip of the mandrel, and extrusion is performed to supply the lubricant. It can be operated continuously for a long time without stopping the machine.

According to the invention described in claim 5 , since the lubricant is composed of a lubricating liquid having a kinematic viscosity at 25 ° C. of ²⁰ to 1000 mm ² / s, the lubricant is smoothly passed through the continuous pores. The contact surface with the resin composition of the base or the core can be reached.

According to the sixth aspect of the present invention, since the lubricating liquid is composed of silicone oil, a flame retardant lubricant layer is formed on the surface of the product, and it is possible to prevent the product from spreading. Further, the lubricant layer imparts gloss to the surface of the product, and the product value can be improved.

According to the invention described in claim 7 , since the lubricating liquid is composed of the polyoxyalkylene compound, the lubricant surface formed on the surface of the product gives gloss to the surface of the product, thereby improving the product value. Can be made.

  Hereinafter, a die of an extruder according to an embodiment of the present invention will be described with reference to FIGS. A die 1 (hereinafter simply referred to as a die) 1 of an extruder according to an embodiment of the present invention is used in an extruder 10 that manufactures a covered electric wire 6 as shown in FIG.

  As illustrated in FIG. 4, the covered electric wire 6 includes a conductive core wire 61 and an insulating covering portion 62. The core wire 61 is composed of a single wire 61a. The strand 61a which comprises the core wire 61 is comprised with electroconductive metals, such as copper and aluminum. The core wire 61 may be formed by twisting a plurality of strands 61a.

  The covering portion 62 covers the outer peripheral surface of the core wire 61. The covering portion 62 is made of, for example, a resin composition 8 (of FIG. 3) based on a polyolefin resin and having a high filler content (high filler). Such a resin composition 8 is easy to form a spear on the die 3 and the core 4 of the die 1. Of course, the resin composition 8 may be of any kind.

  The core wire 61 of the covered electric wire 6 described above is wound around a roll (not shown) before the covering portion 62 is formed. And the core wire 61 is pulled out from the roll and wound up by a winder (not shown). The core wire 61 moves along the arrow A direction (FIG. 1 etc.) between a roll and a winder along the longitudinal direction. The extrusion molding machine 10 is disposed between the roll and the winder, and manufactures the covered electric wire 6 by forming the covering portion 62 on the outer peripheral surface of the core wire 61 that moves along the arrow A direction.

  As shown in FIG. 1, the extrusion molding machine 10 includes at least a screw 11, a cylinder 12, a screw driving unit 13, a heater 14, and a die 1. The screw 11 is formed in a long and substantially cylindrical shape as a whole. The screw 11 is made of a metal member having high wear resistance, for example. The screw 11 includes a shaft portion 11a and a flight 11b standing in a spiral shape from the outer peripheral surface of the shaft portion 11a. The resin composition 8 is passed between the flights 11 b and is transported in the cylinder 12, and is melted by the shearing heat of the screw 11 and the heat from the heater 14 while being transported.

  The cylinder 12 is provided in a cylindrical shape and accommodates the screw 11 therein. The cylinder 12 is made of a metal member having high wear resistance, for example. The cylinder 12 is arranged along the vertical direction. The inner diameter of the cylinder 12 is slightly larger than the outer diameter of the screw 11 and is formed to be substantially constant. The cylinder 12 is provided with a supply port 10a. The supply port 10 a is an opening continuous in the cylinder 12. The supply port 10 a is provided at one end of the cylinder 12. The resin composition 8 is supplied into the cylinder 12 through the supply port 10a. A hopper 15 is attached to the supply port 10a.

  The screw drive unit 13 is composed of a motor or the like. The screw drive unit 13 pivotally supports the screw 11 accommodated in the cylinder 12 so as to be rotatable about its axis, and rotationally drives the screw 11 about the axis.

  The heater 14 is embedded in the outer peripheral wall of the cylinder 12. The heater 14 is, for example, a belt-like plate heater 14. Of course, the heater 14 may be a band-shaped band heater. The heater 14 supplies heat into the cylinder 12.

  The die 1 is attached to the other end portion away from the supply port 10 a of the cylinder 12. The die 1 is a so-called cross head die. As shown in FIG. 2, the die 1 includes a die body 2, a base 3, a core 4, a base cap 31, a hole 23, and a second hole 43.

  The die body 2 is made of, for example, a hard metal material and is formed in a cylindrical shape. The die body 2 includes a small diameter hole 21 and a large diameter hole 22 inside. The small diameter holes 21 are arranged along the vertical direction. The small diameter hole 21 communicates with the inside of the other end of the cylinder 12 and supplies the resin composition 8 melted in the cylinder 12 to the die 1. The large diameter hole 22 is disposed along the horizontal direction and is orthogonal to the small diameter hole 21. The inner diameter of the large diameter hole 22 is larger than the inner diameter of the small diameter hole 21. The large diameter hole 22 accommodates the mandrel 4 inside. The opening of the large-diameter hole 22 is an extrusion port 10b for extruding the resin composition 8 to the outside.

  The base 3 is made of a sintered body, which will be described later, and is formed in a ring shape. The outer diameter of the die 3 is slightly smaller than the inner diameter of the extrusion port 10b. The inner diameter of the base 3 is larger than the outer diameter of the core wire 61 of the covered electric wire 6. The inner diameter of the base 3 is formed so as to gradually decrease from one end of the central axis of the base 3 toward the other end, and the inner diameter on the small diameter side is substantially equal to the outer diameter of the covering portion 62. The base 3 is attached to the extrusion port 10b so that the end on the large diameter side faces the core 4 and the end on the small diameter side is arranged outward.

  A concave groove 32 is provided on the outer peripheral surface of the base 3. The concave groove 32 is formed over the entire circumferential direction of the base 3. The concave groove 32 communicates with an annular portion 23b (described later) of the hole portion 23 when the base 3 is attached to the die body 2.

  The mandrel 4 is formed in a long cylindrical shape. The outer diameter of the mandrel 4 is smaller than the inner diameter of the large-diameter hole 22 of the die body 2. The mandrel 4 is disposed in the large diameter hole 22 of the die body 2 with a gap from the inner surface of the large diameter hole 22. Further, the core 4 is disposed coaxially and in series with the base 3 and is disposed with a gap from the base 3. The molten resin composition 8 is sequentially passed through these gaps and pushed out to the outer peripheral surface of the core wire 61. A through hole 40 is provided at the center of the mandrel 4 along the central axis of the mandrel 4. The through-hole 40 passes the core wire 61 before the coating portion 62 is formed therein. The mandrel 4 includes a main body portion 41 and a tip portion 42.

  The main body 41 is made of a hard metal material. The distal end portion 42 is provided at the end portion of the main body portion 41 on the extrusion port 10b side. The tip portion 42 is composed of a sintered body to be described later. The distal end portion 42 is formed such that the outer diameter gradually decreases as the distance from the main body portion 41 increases. The distal end portion 42 projects outward from the base 3 along the longitudinal direction of the core wire 61.

  The above-described mandrel 4 includes an epoxy-based adhesive or a heat-resistant ceramic as a main body 41 that is cast and a tip 42 that is a sintered body by heating a green compact described later to near the melting point (below the melting point). It is integrally formed by bonding with an adhesive.

  The base 3 and the tip end portion 42 of the core 4 are made of a sintered body. A sintered body is a mixture of one or more kinds of solid powders in a predetermined ratio, then filled in a mold and compression molded to form a green compact, which is heated to near the melting point (below the melting point). Then, the surfaces of the individual solid powders can be melted, and the solid powders can be combined and integrated with each other.

  The sintered body thus obtained has innumerable continuous pores. The continuous pores can be impregnated with a lubricant 7 (FIG. 3) described later. The continuous pores exist inside the sintered body and open to the surface of the sintered body, and the lubricant 7 exists inside and on the surface of the sintered body (in FIG. 3, only the lubricant present on the surface is present). Shown). Further, it is preferable that the continuous pores are impregnated with the lubricant 7 before the extruder 10 is operated. By impregnating the lubricant 7 in advance, the molten resin composition 8 does not enter the continuous pores.

  Moreover, it is preferable that the diameter of a continuous pore is 1-50 micrometers. When the diameter of the continuous pores is less than 1 μm, it is difficult to impregnate the continuous pores with a sufficient amount of the lubricant 7 or allow the lubricant 7 to pass through the continuous pores. Further, if the diameter of the continuous pores is larger than 50 μm, the strength of the sintered body, that is, the die 3 and the core 4 decreases, and the pressure applied to the die 3 and the core 4 during the operation of the extrusion molding machine 10 (at the time of extrusion). There is a possibility that the base 3 and the core 4 are damaged.

The sintered body preferably has a Vickers hardness HV (JIS Z2244) of 680 or more. The Vickers hardness HV is determined by calculating the diagonal lengths d ₁ and d ₂ of the indentation remaining on the test piece after pressing the diamond indenter with a regular quadrangular pyramid (face angle 136 °) into the surface of the test piece and releasing the test force F. Calculated by measuring. The Vickers hardness HV is proportional to the value obtained by dividing the test force F by the surface area S of the recess assuming that the bottom surface is square and the apex angle is the same pyramid as the indenter. The Vickers hardness HV is calculated as follows, assuming that the test force F (N) and the lengths d ₁ and d ₂ of the indentation diagonal lines are average d (mm).
Vickers hardness HV = constant × test force F / indentation surface area S
^{= 0.102 × F / (d 2} /2 × sin (136 ° / 2))
= 0.1891 × F / d ²
When the Vickers hardness HV of the sintered body is less than 680, the strength of the sintered body, that is, the base 3 and the core 4 decreases, and the base 3 and the core 4 may be damaged by the pressure applied during extrusion. .

Examples of such a sintered body having a Vickers hardness HV of 680 or more include a sintered alloy. More preferably, an iron-based sintered alloy containing 10 to 30% of copper is used. By using the iron-based sintered alloy, the Vickers hardness HV can be set to 680 or more, and it can be sufficiently strong without being damaged by the pressure during extrusion. Examples of the iron-based sintered alloy include Nikkaloy EK (manufactured by Hitachi Powdered Metallurgy Co., Ltd., 16 to 22% copper, 0.6 to 1% carbon, less than 1% other than iron, and the balance is iron. Density 6.4 g / cm ³ ).

  Furthermore, it is preferable that the sintered alloy having the above composition is subjected to carburizing and quenching treatment. The carburizing and quenching process is to perform a quenching process after heating the sintered alloy to 850 to 950 ° C. in a carburizing agent and impregnating the surface with the carbon in the carburizing agent. As the carburizing agent, a solid carburizing agent (charcoal, coke, etc.), a gas carburizing agent (coal gas or lamp gas containing carbon monoxide and hydrocarbons) or the like is used. By performing such a carburizing and quenching treatment, the surface of the sintered alloy can be further hardened and the wear resistance can be improved.

The kinematic viscosity at 25 ° C. of the lubricating liquid constituting the lubricant 7 impregnated in the continuous pores of the sintered body (sintered alloy) described above is preferably ^{20 to} 1000 mm ² / s. If the kinematic viscosity is less than 20 mm ² / s, the sintered alloy may flow out of the continuous pores, and a sufficient amount may not be impregnated in the continuous pores. When the kinematic viscosity is larger than 1000 mm ² / s, it becomes difficult to flow through the continuous pores of the size (1 to 50 μm) described above.

Examples of the lubricating liquid having a kinematic viscosity at 25 ° C. of ²⁰ to 1000 mm ² / s include silicone oil and polyoxyalkylene compounds. Silicone oil and polyoxyalkylene compounds are preferable because they have high affinity with the resin composition 8 constituting the covering portion 62 of the covered electric wire 6. These silicone oils and polyoxyalkylene compounds may be used alone or as a mixture of plural kinds. Furthermore, various additives may be added.

Examples of the silicone oil include straight silicone oil such as dimethyl silicone oil, methylphenyl silicone oil, and methyl hydrogen silicone oil, and modified silicone oil. Preferable examples include dimethyl silicone oil and methyl hydrogen silicone oil. More preferably, methyl hydrogen silicone oil is mentioned. Examples of commercially available methyl hydrogen silicone oils include SH1107 (manufactured by Toray Dow Corning), KF-99 and KF-9901 (manufactured by Shin-Etsu Silicone). Kinematic viscosity at these 25 ° C., respectively, 20 mm ² / s, a 20mm ² /s,20.6mm ² / s. Examples of the polyoxyalkylene compound include polyoxyethylene and polyoxypropylene.

  The base cap 31 is formed in a ring shape. The inner diameter of the cap 31 is formed so as to gradually increase from one end of the central axis of the cap 31 toward the other end. The inner diameter of the base cap 31 on the small diameter side is smaller than the outer diameter of the base 3 and larger than the inner diameter of the base 3 on the small diameter side. The base cap 31 is attached to the die body 2 so that the end on the small diameter side faces the base 3 attached to the die body 2, and fixes the base 3 to the die body 2.

  As shown in FIG. 2, the hole 23 is provided at the end of the die body 2 on the extrusion port 10 b side. The hole 23 supplies the lubricant 7 to the base 3 through the lubricant 7 inside. The hole portion 23 includes a straight portion 23a and an annular portion 23b.

  The straight portion 23 a is provided so as to penetrate the end portion of the die body 2 on the extrusion port 10 b side, and is orthogonal to the large-diameter hole 22 of the die body 2. The straight line portion 23 a connects the outside and the inside of the large diameter hole 22. The front end of the straight portion 23a on the large-diameter hole 22 side opens toward the outer peripheral surface of the base 3 attached to the extrusion port 10b.

  The annular portion 23b is connected to the end portion of the linear portion 23a on the large diameter hole 22 side, and is provided in a concave shape from the inner surface overlapping the outer peripheral surface of the base 3 of the large diameter hole 22. The annular portion 23 b is provided over the entire circumferential direction of the die body 2. The annular portion 23 b communicates with the concave groove 32 of the base 3 when the base 3 is attached to the die body 2.

  As shown in FIG. 1, a lubricant supply source 51 is connected to the outer end of the linear portion 23a. In addition, a pressurized gas supply source 52 is connected to the lubricant supply source 51. The pressurized gas supply source 52 sends the pressurized gas of a predetermined pressure to the lubricant supply source 51, thereby causing the lubricant 7 to flow sequentially into the linear portion 23 a, the annular portion 23 b, and the recessed groove 32, and the base 3 Lubricant 7 is supplied. The lubricant 7 passes from the outer peripheral surface of the base 3 through the continuous pores of the sintered body constituting the base 3, and reaches the inner surface 3 a of the base 3, that is, the contact surface with the resin composition 8 as shown in FIG. 3. To do.

  As shown in FIG. 2, the second hole 43 is provided in the mandrel 4. The second hole 43 is formed along the central axis of the mandrel 4, and two second holes 43 are provided across the central axis of the mandrel 4. The second hole 43 is provided through the main body 41 of the mandrel 4. The tip of the second hole 43 is open toward the back surface of the tip 42 of the mandrel 4, and connects the outside and the tip 42 of the mandrel 4. The second hole portion 43 supplies the lubricant 7 to the tip end portion 42 of the mandrel 4 through the lubricant 7 therein.

  As shown in FIG. 1, a lubricant supply source 53 is connected to the external end of the second hole 43 described above. In addition, a pressurized gas supply source 54 is connected to the lubricant supply source 53. The pressurized gas supply source 54 feeds the lubricant 7 to the tip portion 42 of the mandrel 4 by feeding the lubricant 7 into the hole 23 by sending a pressurized gas of a predetermined pressure to the lubricant supply source 53. . The lubricant 7 passes through the continuous pores of the sintered body constituting the tip portion 42 from the aforementioned back surface of the tip portion 42 of the mandrel 4, and as shown in FIG. 3, the outer surface of the tip portion 42 of the mandrel 4. 42a, that is, the contact surface with the resin composition 8 is reached.

  The pressure of the pressurized gas sent out by the pressurized gas supply sources 52 and 54 described above should be equal to or higher than the pressure applied to the vicinity of the die 3 when the extruder 10 is operated and the resin composition 8 is pushed out from the extrusion port 10b. Thus, the lubricant 7 can be efficiently supplied to the tip 3 of the base 3 and the core 4. For example, when the resin composition 8 is polypropylene or polyethylene, the pressure applied to the vicinity of the die 3 is 3 to 4 MPa, and therefore the pressure of the pressurized gas is preferably 3 to 5 MPa.

  When manufacturing the covered electric wire 6 with the extrusion molding machine 10 having the above-described configuration, first, the core wire 61 drawn from the roll is passed through the core 4 and the base 3 of the die 1 in this order, and then the winding machine is used. Install it. Then, the resin composition 8 is supplied from the supply port 10 a of the cylinder 12, the screw 11 is rotated, and the resin composition 8 is melted in the cylinder 12.

  Thereafter, the winder is driven to pull the core wire 61 from the roll and move it along the arrow A direction. Then, the resin composition 8 melted in the cylinder 12 is pushed out from between the inner surface 3 a of the base 3 and the outer surface 42 a of the tip end portion 42 of the core metal 4, and the resin composition 8 extends along the direction of arrow A. A covering portion 62 is formed by covering the outer peripheral surface of the moving core wire 61. After the covering portion 62 is cooled by a cooling device (not shown), the core wire 61 covered with the covering portion 62, that is, the covered electric wire 6, is sequentially wound around the winding machine. As described above, the covered electric wire 6 is manufactured.

  Even when the covered electric wire 6 is manufactured continuously for a long time, the base 3 and the core 4 are made of a sintered body having continuous pores that can be impregnated with the lubricant 7. 3a and the outer surface 42a of the distal end portion 42 of the mandrel 4 are highly slippery, so even if the resin composition 8 has a high filler content based on, for example, a polyolefin resin, these inner surfaces 3a and There is no occurrence of spears or the like on the outer surface 42a.

  Further, by driving the extrusion molding machine 10 for a long time, the lubricant 7 in the continuous pores opened on the inner surface 3a of the base 3 and the outer surface 42a of the distal end portion 42 of the core metal 4 adheres to, for example, the covering portion 62 and decreases. However, since the lubricant 7 is constantly supplied from the inside continuous pores and the lubricant 7 is always supplied from the lubricant supply sources 51 and 53, a predetermined amount of the lubricant 7 is always applied to the base 3. It can exist on the inner surface 3 a and the outer surface 42 a of the tip 42 of the mandrel 4.

  According to the present embodiment, since the die 3 is composed of a sintered body having continuous pores that can be impregnated with the lubricant 7, contact with the inner surface 3 a of the die 3, that is, the resin composition 8 from inside the continuous pores. Lubricant 7 is constantly supplied to the surface to improve the lubricity of the contact surface, preventing the occurrence of cracks in the mouthpiece 3, improving the surface quality of the outer peripheral surface of the covering portion 62, and the extruder. 10 can be operated continuously for a long time. Moreover, by improving the lubricity of the contact surface, the extrusion speed of the extruder 10 can be set high, and various resin compositions 8 from low viscosity to high viscosity can be handled.

  Since the tip 42 of the mandrel 4 is formed of a sintered body having continuous pores that can be impregnated with the lubricant 7, the outer surface 42 a of the tip 42 of the mandrel 4, that is, the resin composition 8. Lubricant 7 is always supplied to the contact surface with the contact surface to improve the lubricity of the contact surface, prevent the occurrence of spears at the tip portion 42, and improve the surface quality of the inner surface of the covering portion 62, in particular. The extrusion molding machine 10 can be operated continuously for a long time. Moreover, by improving the lubricity of the contact surface, the extrusion speed of the extruder 10 can be set high, and various resin compositions 8 from low viscosity to high viscosity can be handled.

  Since the sintered body has a Vickers hardness HV of 680 or more, the sintered body is not damaged by the pressure applied during operation of the extrusion molding machine 10, and the die 3 and the core 4 having sufficient strength. It can be.

  Since the sintered body is made of an iron-based sintered alloy containing 10 to 30% of copper, the Vickers hardness HV can be easily set to 680 or more, and the base 3 and the mandrel having sufficient strength 4 can be used.

  Since the diameter of the continuous pores is 1 to 50 μm, the lubricant 7 can be smoothly passed through the continuous pores while maintaining the strength of the sintered body.

  A hole 23 through which the lubricant 7 supplied to the base 3 passes is inserted into the die body 2, and the die body 2 is connected to the straight portion 23 a, the tip of which opens toward the outer peripheral surface of the base 3. Since the annular portion 23b is provided so as to be recessed from the inner surface of the die body 2 over the entire circumferential direction, the lubricant 7 can be evenly supplied from the entire circumferential direction of the base 3 to the entire inside of the base 3. Further, since the lubricant 7 can be always supplied to the die 3 even when the extruder 10 is in operation, the lubricant 7 is not exhausted from the die 3, and the extruder 10 can be supplied to supply the lubricant 7. Can be operated continuously for a long time without stopping.

  A second hole 43 through which the lubricant 7 supplied to the distal end portion 42 of the mandrel 4 passes is penetrated through the main body 41 of the mandrel 4, and the distal end thereof faces the back surface of the distal end portion 42 of the mandrel 4. Therefore, the lubricant 7 can be reliably supplied to the distal end portion 42 of the mandrel 4. Further, since the lubricant 7 can be always supplied to the tip 42 of the mandrel 4 even when the extrusion molding machine 10 is in operation, the lubricant 7 is not depleted from the tip 42 of the mandrel 4. 7 can be operated continuously for a long time without stopping the extrusion molding machine 10.

Since the lubricant 7 is composed of a lubricating liquid having a kinematic viscosity at 25 ° C. of ²⁰ to 1000 mm ² / s, the resin composition of the base 3 and the core 4 is obtained by smoothly passing the lubricant 7 through the continuous pores. 8 can reach the contact surface.

  Since the lubricating liquid is composed of silicone oil, a flame retardant lubricant layer is formed on the surface of the product, thereby preventing the product from spreading. Further, the lubricant layer imparts gloss to the surface of the product, and the product value can be improved.

  Since the lubricating liquid is composed of a polyoxyalkylene compound, gloss is imparted to the surface of the product by the lubricant layer formed on the surface of the product, and the product value can be improved.

  In the present embodiment, both the base 3 and the tip 42 of the core 4 are made of a sintered body. This is because, as in the present embodiment, when the tip 42 of the core 4 protrudes outside the base 3 (downstream in the direction of arrow A), the inner surface 62a of the cover 62 (FIG. This is because the eyes are sprinkled on the surface that contacts the core wire 61. However, in the present invention, when the tip end portion 42A of the core 4 is on the inner side (upstream side in the arrow A direction) of the base 3 as shown in FIG. Therefore, the tip end portion 42A of the mandrel 4 need not necessarily be formed of a sintered body.

  In the present embodiment, the two second holes 43 are provided. However, three or more second holes 43 may be provided so that the lubricant 7 can be supplied to the tip 42 of the mandrel 4 more reliably. . Moreover, in this embodiment, although the die | dye 1 was used for the extruder 10 which manufactures the covered electric wire 6, of course, it may be used for the extruder 10 which manufactures another product.

  In addition, embodiment mentioned above only showed the typical form of this invention, and this invention is not limited to embodiment. That is, various modifications can be made without departing from the scope of the present invention.

It is explanatory drawing which shows the structure of the extrusion machine in which the die | dye concerning one Embodiment of this invention is used. FIG. 2 is a cross-sectional view of the die shown in FIG. 1. It is sectional drawing which expands and shows the principal part of die | dye shown by FIG. It is a cross-sectional perspective view of the electric wire manufactured with the extrusion molding machine shown by FIG. It is a partial sectional view showing a die concerning other embodiments of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 (Die of an extrusion molding machine) 2 Die body 3 Base 4 Core metal 7 Lubricant 8 Resin composition 10b Extrusion port 12 Cylinder 23 Hole 23a Linear part 23b Ring part 42 Tip part 43 2nd hole part

Claims (7)

In a die of an extrusion molding machine comprising: a die body for extruding a resin composition melted in a cylinder; a die attached to an extrusion port of the die body; and a mandrel disposed in the die body.
The base is composed of a sintered body having continuous pores that can be impregnated with a lubricant,
The tip of the mandrel is composed of a sintered body having continuous pores that can be impregnated with a lubricant,
Vickers hardness HV of the sintered body is 680 or more as a minimum value ,
A die for an extruder, wherein the sintered body is made of an iron-based sintered alloy containing 10 to 30% of copper. The die for an extruder according to claim 1 , wherein the diameter of the continuous pores is 1 to 50 µm. A hole through which the lubricant supplied to the base passes is a straight part that penetrates the die body and the tip of the hole opens toward the outer peripheral surface of the base. die extrusion molding machine according to claim 1 or 2, characterized in that it comprises an annular portion provided on the recessed from the inner surface of the die body over the entire direction. 2. The second hole portion through which the lubricant is passed is formed so as to penetrate the main body portion of the mandrel, and the tip of the second hole portion opens toward the back surface of the tip portion of the mandrel. The die of the extrusion molding machine according to any one of to 3 . The die for an extruder according to any one of claims 1 to 4 , wherein the lubricant is composed of a lubricating liquid having a kinematic viscosity at 25C of ²⁰ to 1000 mm2 / s. . 6. The die for an extruder according to claim 5 , wherein the lubricating liquid is made of silicone oil. 6. The die for an extruder according to claim 5 , wherein the lubricating liquid is composed of a polyoxyalkylene compound.

Images