JP2005066958A - Extruder and method for extrusion of cylindrical ceramic body using the same - Google Patents

Abstract

Since the ceramic raw material moves forward while rotating the extrusion screw, when the ceramic raw material is pushed out of the mold, the tip of the inner die is rotated in a circle to cause a vibration, and the cylindrical ceramic body Concentricity and inner diameter roundness deteriorate.
The ratio of the outer diameter D of the extrusion screw to the inner diameter d of the outer die is set to D / d = 12 to 30, thereby increasing the amount of extrusion per unit time and lowering the rotation speed of the extrusion screw.
[Selection] Figure 1

Description

  The present invention relates to an extrusion molding machine for a ceramic ferrule body for an optical connector for fixing an optical fiber used for optical communication or the like, and an extrusion molding method using the same.

  In recent years, optical communication using an optical fiber has been used with an increase in the amount of information in communication. In this optical communication, an optical connector as shown in FIG. 4 is used for connecting optical fibers or connecting an optical fiber and various optical elements.

  For example, in the case of a connector for connecting optical fibers, the end portions of the optical fiber 42 are held in the through holes formed in the ferrule 41, and the pair of ferrules 41 are inserted from both ends of the sleeve 43 so as to have a convex spherical shape inside. It is the structure which made the end surfaces processed into contact | abut.

  Various materials such as ceramics, metal, plastic, and glass have been made as materials for the ferrule 41 and the sleeve 43, but most of them are made of ceramics at present. The reason for this is that ceramics have high processing accuracy, so the tolerance of the inner and outer diameters can be as high as 1 μm or less, and because ceramics have a low coefficient of friction, the insertability of the optical fiber 42 is excellent and the rigidity is high. This is because the coefficient of thermal expansion is low, so it is stable against external stress and temperature change, and has excellent corrosion resistance.

  In the ferrule 41, the concentricity of the inner diameter and the outer diameter is particularly important. This is because the end faces of the ferrule 41 need to be brought into contact with each other with high precision inside the sleeve 43 in order to reduce the optical connection loss, and a concentricity dimension of 1 μm or less is required. For this reason, processing is performed using ceramics as described above, but it is required that the concentricity and inner diameter roundness of the cylindrical ceramic body used for processing are also good.

  The cylindrical ceramic body is formed in a predetermined shape by extrusion molding, press molding, injection molding, or the like, and, if necessary, cut in a ceramic material, and then in an air atmosphere at a firing temperature in the range of 1350 ° C. to 1450 ° C. It is obtained by baking with. In press molding or injection molding, the outer die that forms the outer periphery of the ferrule 41 and the inner die that forms the insertion hole for the optical fiber 42 of the ferrule 41 are separated for each molding shot. While it is difficult to improve the concentricity of the inner and outer diameters, the extrusion molding has a structure in which the outer die and the inner die are fixed. Therefore, the concentricity of the cylindrical ceramic body is relatively high. It is possible to

  As shown in FIG. 3, the mold 13 used for extrusion molding includes an outer die 11 that forms an outer peripheral portion of a ferrule 41 and an inner die 12 that forms an insertion hole for an optical fiber 42, and the inner die 12 is a spider 19. It is bonded and fixed to the outer die 11 at a support portion called. At this time, the position of the inner die 12 is adjusted so that the concentricity between the inner diameter portion of the outer die 11 and the outer diameter portion of the inner die 12 becomes zero.

  The ceramic raw material introduced from the supply hopper 31 is kneaded by the upper screw 32 and then enters the vacuum chamber 33. This vacuum chamber 33 is for performing vacuum degassing of the ceramic raw material passing through the inside of the extrusion molding machine, and is connected to a vacuum pump device 34 installed on a gantry inside the extrusion molding machine by an air tube 35, It has a structure that can be evacuated. The vacuum-degassed ceramic raw material is pressurized by the rotation of the extrusion screw 14 and compressed by the mold 13 to form a molded body having a predetermined concentricity dimension and extruded.

Conventionally, an extruder has been selected so that the ratio of the outer diameter D of the extrusion screw 14 to the inner diameter d of the outer die 11 is D / d = 3-10. This ratio is empirical, and the range is such that if D / d is less than 3, the ceramic raw material may not be sufficiently compressed, and the density of the molded body may be reduced. This is because when D / d is larger than 10, even if the gear ratio is set to a low value, the molding speed cannot be increased and the molded body cannot be taken up and stored. For this reason, in the case of a product having a small outer diameter, an extruder having a small outer diameter of the extrusion screw 14 so that the ratio of the outer diameter D of the extrusion screw 14 to the inner diameter d of the outer die 11 is D / d = 3-10. Was used to perform extrusion molding.
JP 2002-55255 A

  However, the position of the inner die 12 of the mold 13 and the outer diameter portion of the inner die 12 are adjusted so that the concentricity is 0, and then the inner die 12 is attached to the outer die 11 by the spider 19 even when the die is fixed. Therefore, there is a problem that the tip of the inner die 12 is shaken by various fluctuations during extrusion molding, and the concentricity and the inner diameter roundness are deteriorated. Here, since the tip of the inner die 12 is used as an insertion hole for the optical fiber 42 having a diameter of 0.125 mm after processing, the outer diameter is extremely thin as 0.15 to 0.20 and is easily affected by minute fluctuations.

  There are the following two factors that cause the tip of the inner die 12 to shake during extrusion molding, resulting in poor concentricity. One is a case where the ceramic raw material moves forward while rotating the extrusion screw 14, so that when the ceramic raw material is pushed out from the mold 13, the tip of the inner die 12 is rotated in a circle to cause a shake. . Further, when the molding speed is increased in order to improve the productivity, there is a problem that the runout is further increased because the rotational speed of the extrusion screw 14 is increased.

  The other is a case where the tip of the inner die 12 vibrates due to vibration of the extrusion molding machine, causing vibration. The largest cause of vibration is the vibration of the vacuum pump device 34. This vacuum pump device 34 is for vacuum deaeration of the ceramic material passing through the inside of the extrusion molding machine and to increase the density of the molded body, but it is installed on the same pedestal such as the inside of the extrusion molding machine. Therefore, there has been a problem that the rotational vibration of the pump vibrates the entire extruder and the tip of the inner die 12 through the gantry.

  The deflection of the tip of the inner die 12 due to the above causes is particularly a problem in a ceramic ferrule body for an optical connector that requires an outer diameter of the tip of the inner die 12 as extremely small as φ0.15 to 0.20 and requires high-precision concentricity. It was.

  Therefore, the present invention has been made in view of the above-described problems. The extrusion screw is rotated to apply pressure to the raw material, and the raw material is passed through a mold composed of an outer die and an inner die to form a cylindrical shape. In the extrusion molding machine, the ratio of the outer diameter D of the extrusion screw to the inner diameter d of the outer die is D / d = 12-30.

  The outer diameter D of the extrusion screw can be changed with respect to the inner diameter d of the outer die. Further, the number of revolutions of the extrusion screw is controlled by an inverter so that the molding speed of the molded body is 100 to 200 mm / s.

  That is, as a result of various experiments conducted by the inventors, the ratio of the outer diameter D of the extrusion screw to the inner diameter d of the outer die is set to D / d = 12 to 30, thereby increasing the amount of extrusion per unit time. The number of rotations of the extrusion screw can be lowered, the deflection of the inner die tip caused by the rotation of the ceramic raw material accompanying the rotation of the extrusion screw is reduced, and the concentricity and inner diameter roundness of the cylindrical ceramic body can be improved. I found it. Further, the productivity is impaired by controlling the inverter so that the molding speed of the molded body becomes 100 to 200 mm / s after setting the ratio of the outer diameter D of the extrusion screw to the inner diameter d of the outer die. Therefore, the number of revolutions of the extrusion screw can be reduced, and the fluctuation of the tip of the inner die caused by the rotation of the ceramic raw material accompanying the rotation of the extrusion screw can be reduced.

  Furthermore, the present invention provides a vacuum pump device for vacuum degassing of the ceramic raw material passing through the inside of the extrusion molding machine on the gantry outside the extrusion molding machine. It is characterized by connecting only with a tube.

  In other words, by installing the vacuum pump device on a stand outside the extrusion machine and connecting it with the vacuum chamber of the extrusion machine only by the air tube, the rotational vibration of the vacuum pump device is not transmitted to the inner die tip, and the inner die tip , And the concentricity and inner diameter roundness of the cylindrical ceramic body can be improved.

  As described above, in the extrusion molding machine of the present invention and the cylindrical ceramic body extrusion method using the same, the ratio of the outer diameter D of the extrusion screw to the inner diameter d of the outer die is D / d = 12-30. Thus, the amount of extrusion per unit time increases, the number of rotations of the extrusion screw can be reduced, and the deflection of the inner die tip caused by the rotation of the ceramic raw material accompanying the rotation of the extrusion screw is reduced, and the cylindrical ceramic body The concentricity and the inner diameter roundness can be improved. Further, the productivity is impaired by controlling the inverter so that the molding speed of the molded body becomes 100 to 200 mm / s after setting the ratio of the outer diameter D of the extrusion screw to the inner diameter d of the outer die. The number of revolutions of the extrusion screw can be reduced, the fluctuation of the tip of the inner die caused by the rotation of the ceramic raw material accompanying the rotation of the extrusion screw can be reduced, and the concentricity and inner diameter roundness of the cylindrical ceramic body can be reduced. Can be better.

  The extrusion molding machine of the present invention and the extrusion molding method of a cylindrical ceramic body using the extrusion molding machine have a vacuum pump device for vacuum degassing of the ceramic raw material passing through the inside of the extrusion molding machine on a stand outside the extrusion molding machine. Installed and connected to the vacuum degassing chamber of the extrusion molding machine only with the air tube, the rotational vibration of the vacuum pump device is not transmitted to the tip of the inner die, and the deflection of the tip of the inner die is reduced, and the cylindrical ceramic body The concentricity and the inner diameter roundness can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a tip mold part of an extrusion molding machine according to the present invention. The mold 13 is constituted by an outer die 11 and an inner die 12. The outer die 11 is housed inside a mold holder 17 fixed to the extrusion molding machine by a fixing means 18. Further, the inner die 12 has an outer diameter of φ0.15 to 0.20, and the spider 19 causes the outer die 11 to have a concentricity between the inner diameter portion of the outer die 11 and the outer diameter portion of the inner die 12. 11 is bonded and fixed.

  The ceramic raw material is pressurized by the rotation of the extrusion screw 14, passes through the auger barrel 15, is compressed by the tapered barrel 16, and then flows into the die portion. Further, after being compressed by the tapered portion 11 a of the outer die 11, a molded body having a predetermined concentricity dimension is formed and extruded while passing through the gap between the outer die 11 and the inner die 12.

  At this time, the ratio of the outer diameter D of the extrusion screw 14 to the inner diameter d of the outer die 11 is set to D / d = 12 to 30, more preferably D / d = 15 to 22. When this is smaller than D / d = 12, that is, when the difference between the inner diameter d of the outer die 11 and the outer diameter D of the extrusion screw 14 is small, the amount of extrusion per unit time is small, so the predetermined molding speed is set. Therefore, the rotational speed of the extrusion screw 14 must be increased, and the deflection of the tip of the inner die 12 caused by the rotation of the ceramic raw material accompanying the rotation of the extrusion screw 14 increases, resulting in the concentricity and inner diameter of the cylindrical ceramic body. This is because the circularity worsens. When D / d is larger than 30, that is, when the difference between the inner diameter d of the outer die 11 and the outer diameter D of the extrusion screw 14 is large, the compression rate of the ceramic raw material becomes too high and the molding pressure becomes high. This is because the deflection of the tip of the inner die 12 becomes large. Further, when D / d becomes large, there are cases where extrusion cannot be performed. Thus, by setting it as the range of D / d = 12-30, since the extrusion amount per unit time can increase and the rotation speed of the extrusion screw 14 can be made low, the ceramic raw material accompanying rotation of the extrusion screw 14 can be reduced. The deflection of the tip of the inner die 12 caused by the rotation is reduced, and the concentricity and inner diameter roundness of the cylindrical ceramic body can be improved.

  Moreover, after setting it as the range of D / d = 12-30, the rotation speed of the extrusion screw 14 can be made low without impairing productivity by making the shaping | molding speed | rate of a molded object into 100-200 mm / s, The deflection of the tip of the inner die 12 caused by the rotation of the ceramic raw material accompanying the rotation of the extrusion screw 14 can be reduced. Here, when the molding speed is set to 100 to 200 mm / s, when the speed is slower than 100 mm / s, the rotational speed of the extrusion screw 14 can be lowered, and the inner die generated by the rotation of the ceramic raw material accompanying the rotation of the extrusion screw 14. This is because the tip 12 runout can be reduced, but the productivity is considerably deteriorated and is not practical. When the speed is higher than 200 mm / s, the rotational speed of the extrusion screw 14 is increased, and the deflection of the tip of the inner die 12 caused by the rotation of the ceramic raw material accompanying the rotation of the extrusion screw 14 is increased, and the concentricity and inner diameter of the cylindrical ceramic body are increased. This is because the roundness deteriorates.

  The extrusion screw 14 is driven by a motor, and is controlled by an inverter. This is because it is necessary to drive the extrusion screw 14 at a low rotational speed in order to reduce the deflection of the tip of the inner die 12.

  The outer die 11 and the inner die 12 constituting the mold 13 can be configured using raw materials such as carbon steel, stainless steel, and super steel, but are rigid in order to reduce the deflection of the tip of the inner die 12. It is desirable to use high super steel. Furthermore, it is desirable to use super steel having high hardness for the reason that abrasion resistance and corrosion resistance are necessary and that it is necessary to process with high accuracy.

  FIG. 2 is a sectional view showing the extrusion molding machine of the present invention. The ceramic raw material is fed from the supply hopper 31, kneaded by the upper screw 32, enters the vacuum chamber 33, and is vacuum degassed by the vacuum pump device 21. Here, in the conventional extrusion molding machine, as shown in FIG. 3, the vacuum pump device 34 is installed on a frame inside the extrusion molding machine together with a motor for driving a screw, and is connected to the vacuum chamber 33 by an air tube 35. In contrast, in the extrusion molding machine of the present invention, as shown in FIG. 2, the vacuum pump device 21 is installed on a stand outside the extrusion molding machine and is connected only by the vacuum chamber 33 and the air tube 22 of the extrusion molding machine. Therefore, the rotational vibration of the vacuum pump device 21 is not transmitted to the tip of the inner die 11, and the deflection of the tip of the inner die 11 is reduced, thereby improving the concentricity and inner diameter roundness of the cylindrical ceramic body. Can do.

  Further, the ceramic raw material is extruded from the mold 13 while being compressed by the lower extrusion screw 14. Here, the extrusion screw 14 is fixed to the extruder main body by a shaft coupling, and the extrusion screw barrel 36 that functions as a cylinder outside the extrusion screw 14 is fixed to the extruder main body by screws. Both are easily removable. And the extrusion screw 14 according to the outer diameter D of the extrusion screw 14 and the extrusion screw 14 which has the outer diameter D according to the inner diameter d of the outer die 11 is attached so that it may become the range of D / d = 12-30. Is possible. Here, the extrusion screw barrel 36 is provided with a clearance so as not to come into contact with the extrusion screw 14 when the extrusion screw 14 rotates, and the clearance is about 1 mm.

  Since the outer diameter on the shaft coupling side of the extrusion screw 14 is constant, the outer diameter D on the distal end side of the extrusion screw 14 is narrow at the extrusion screw barrel 36 in order to set the range of D / d = 12-30. It has a stepped structure.

  As an example of the present invention, an experiment was performed by the following method.

  The product shape was a ferrule 41 made of zirconia ceramic for an optical connector shown in FIG. 4, and each sample was formed as follows using the extrusion molding machine of the present invention shown in FIGS. 1 and 2.

First, a material in which a zirconia raw material and a binder necessary for extrusion molding are mixed is put into an extrusion molding machine, and the ratio of the outer diameter D of the extrusion screw 14 to the inner diameter d of the outer die 11 is set to D / d as shown in FIG. = Extruded by using the outer die 11 and the extrusion screw 14 to be 10, 11.7, 16.7, 22.9, 28.6, 33.3, 40 (samples A, B, D, G, H, I). Here, the positions of the outer die 11 and the inner die 12 were adjusted using a projector so that the concentricity was 0, and then bonded and fixed. Further, extrusion molding was performed under the condition of D / d = 16.7, changing the molding speed to 50, 100, 200, and 300 mm / s. (Samples C, D, E, and F) Furthermore, after the vacuum pump device 34 was installed outside the extrusion molding machine, extrusion molding was performed under the conditions of D / d = 16.7 and a molding speed of 100 mm / s. (Sample J)
Each sample was dried and fired under the same conditions, and then L-shaped cut processing was performed to prepare 50 samples. The shape of the sample is such that, in the mold 13, the inner peripheral surface of the outer die 11 has an inner diameter of about φ3 and 3.5 mm, and the outer peripheral surface of the inner die 12 has an outer diameter of about φ0.15 mm. The outer diameter was about 2.5 to 3.0 mm, the inner diameter was about 0.125 mm, and the cylindrical shape was about 12 mm long by cutting.

  For this cylindrical sample, the concentricity and inner diameter roundness of each sample were measured. Here, the concentricity was measured by a contact-type sensor, with the inner diameter of the sample supported at the center from both sides, and the deflection of the outer periphery when the sample was rotated. The inner diameter roundness was measured by taking the inner diameter of the end face of the sample with a CCD and analyzing the image.

Table 1 shows the results of measuring the concentricity and inner diameter roundness of these cylindrical samples.

  First, in the test in which the ratio of the outer diameter D of the extrusion screw 14 to the inner diameter d of the outer die 11 and D / d were changed at the same molding speed, D / d = 11.7 to 33.3. , D, G and H are samples D, G having a concentricity of 3 to 8 μm and an inner diameter roundness of 0.09 to 0.16 μm, particularly in the range of D / d = 16.7 to 22.9. The concentricity is 3 to 5 μm, the inner diameter roundness is 0.09 to 0.13 μm, and the larger the D / d, the better the tendency. This is because when the forming speed is constant, the amount of extrusion per unit time increases as D / d increases, so that the number of revolutions of the extrusion screw 14 can be reduced. It is considered that the concentricity and inner diameter roundness of the cylindrical ceramic body are improved by reducing the deflection of the tip of the inner die 12 that occurs. On the other hand, the sample A has a bad concentricity of 21 μm and an inner diameter roundness of 0.54 μm. This is because D / d is small, the amount of extrusion per unit time increases, the rotation speed of the extrusion screw 14 increases, and the deflection of the tip of the inner die 12 caused by the rotation of the ceramic raw material accompanying the rotation of the extrusion screw 14 increases. It is thought that the concentricity and inner diameter roundness of the cylindrical ceramic body deteriorated. Sample I also has a concentricity of 17 μm and an inner diameter roundness of 0.33 μm, but this is a large D / d and the rotational speed of the extrusion screw 14 is low, but the compression rate of the ceramic raw material is too high. This is probably because the molding pressure has increased and the deflection of the tip of the inner die 12 has increased.

  Next, in a test in which the molding speed was changed with the same D / d, samples C, D, and E having a molding speed in the range of 50 to 200 had a concentricity of 3 to 6 μm and an inner diameter roundness of 0.11. It was good with -0.15 micrometer, and the tendency which became so good that the shaping | molding speed was slow was acquired. This is because, when D / d is constant, the lower the forming speed, the lower the rotational speed of the extrusion screw 14 and the smaller the deflection of the tip of the inner die 12 caused by the rotation of the ceramic raw material accompanying the rotation of the extrusion screw 14. It is thought that it is to become. However, since slowing down the molding speed deteriorates productivity, the condition of the molding speed of 50 mm / s (sample C) is out of the scope of the present invention. Further, the molding speed of 300 mm / s (sample F) is poor with a concentricity of 16 μm and an inner diameter roundness of 0.27 μm. This is because the deflection of the tip of the inner die 12 is increased due to the high rotation speed of the extrusion screw 14. it is conceivable that.

  Finally, in the test (Sample J) in which the vacuum pump device 34 was installed outside the extrusion molding machine and subjected to extrusion molding, the concentricity was 5 to 2 μm with respect to the sample D having the same D / d and molding speed conditions. Further, the roundness of the inner diameter was improved from 0.13 to 0.08 μm. This is considered that the rotational vibration of the vacuum pump device 34 is not transmitted to the tip of the inner die 12, the deflection of the tip of the inner die 12 is reduced, and the concentricity and inner diameter roundness of the cylindrical ceramic body are improved. It is done.

  The extrusion molding machine and the extrusion molding method using the same according to the present invention are not limited to the ceramic ferrule body for an optical connector, but have a cylindrical shape and require a concentricity accuracy between an inner diameter and an outer diameter. Applicable to the body. Examples include capillaries, nozzles, fluid bearing sleeves, and the like.

  It has a cylindrical shape and can be used for ceramic parts that require the accuracy of concentricity between the inner and outer diameters. Examples include a ceramic ferrule for an optical connector that requires high-precision concentricity of 1 μm or less, a capillary, a nozzle, a sleeve of a fluid bearing, and the like.

It is sectional drawing which shows the front-end | tip metal mold | die part of the extrusion molding machine of this invention. It is sectional drawing which shows the extrusion molding machine of this invention. It is sectional drawing which shows the conventional extrusion molding machine. It is sectional drawing which shows the structure of the general optical connector which connects optical fibers.

Explanation of symbols

11: Outer die 11a: Tapered portion 12: Inner die 13: Mold 14: Extrusion screw 15: Auger barrel 16: Tapered barrel 17: Mold holder 18: Fixing means 19: Spider 21: Vacuum pump device 22: Air tube 31 : Supply hopper 32: Upper stage screw 33: Vacuum chamber 34: Vacuum pump device 35: Air pipe 36: Extrusion screw barrel 41: Ferrule 42: Optical fiber 43: Split sleeve

Claims (6)

In an extrusion molding machine in which a pressure is applied to a raw material by rotating an extrusion screw and the raw material is passed through a mold composed of an outer die and an inner die to form a cylindrical shape, the outer diameter D and outer diameter of the extrusion screw An extrusion molding machine characterized in that the ratio of the inner diameter d of the die is D / d = 12-30. The extrusion molding machine according to claim 1, wherein the outer diameter D of the extrusion screw can be changed with respect to the inner diameter d of the outer die. The extrusion according to claim 1 or 2, wherein a vacuum pump device for performing vacuum degassing of the raw material is installed on a stand outside the extrusion molding machine, and is connected to the vacuum chamber of the extrusion molding machine only by an air tube. Molding machine. The extrusion molding method of the cylindrical ceramic body which uses the extrusion molding machine described in any one of Claims 1-3. The method for extruding a cylindrical ceramic body according to claim 4, wherein the number of revolutions of the extruding screw is controlled by an inverter so that the forming speed is 100 to 200 mm / s. 6. The method for extruding a cylindrical ceramic body according to claim 4, wherein the cylindrical ceramic body is a ferrule for an optical connector.

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