JP2008155443A - Screw extruder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screw extruder for obtaining a rod-shaped molding reduced in density irregularity by providing a through-hole unformed region so as to cover the outlet part of a mold when looked from a screw leading end part without using a cylindrical straightening part. <P>SOLUTION: In the screw extruder 1, a tabular member 9 having a plurality of through-holes 9a is provided between the screw leading end part 7a and the outlet part 8a of the mold 8 and a through-hole unformed region 9b is provided to the tabular member 9 so as to cover the outlet part 8a when looked from the screw leading end part 7a to inexpensively and efficiently manufacture the rod-shaped molding reduced in density irregularity, reduced in the occurrence of internal voids and reduced in the occurrence of deformation or cracking at the time of drying and baking at a low cost. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a screw-type extruder for obtaining a rod-shaped molded body.

  Conventionally, an extrusion molding method has been used as a molding method for obtaining a rod-shaped molded body made of ceramics or the like. The extrusion molding machine used for this extrusion molding method continuously forms a rod-shaped molded body having a specific outlet shape in cross-sectional shape by extruding a molding material prepared in a clay shape from a mold having a specific outlet shape. And can be suitably used for efficient mass production of rod-shaped molded bodies.

  This extrusion molding machine includes a plunger type and a screw type, but the screw type is superior in that it can be continuously formed and has excellent mass productivity as compared with the plunger type in which the supply of molding material is a batch type. Extruders are commonly used.

  FIG. 7 is a schematic cross-sectional view showing an example of a conventional screw-type extruder.

  The screw-type extruder 20 shown in FIG. 7 has a vacuum chamber 25 between an upper screw 24 and a lower screw 27. The upper screw 24 covers the upper barrel 23, and the lower screw 27 covers the lower barrel 26. It has been broken. In addition, a molding material inlet 22 is opened in a part of the upper barrel 23, and a mold 28 is connected to the outlet side of the lower barrel 26.

  Furthermore, the upper stage screw 24 and the lower stage screw 27 are formed with a spiral convex portion 31, one of which is connected and fixed to the upper stage bearing 29 and the lower stage bearing 30, respectively, and connected to a power source (not shown). . The vacuum chamber 25 is connected to a vacuum pump (not shown) for evacuating the inside of the vacuum chamber 25.

  Next, a procedure for forming a rod-shaped molded body using the screw type extruder 20 will be described.

  First, for example, flour and water, or ceramic powder, a binder and water are mixed and kneaded to obtain a clay-like molding material. Then, this molding material is introduced from the inlet 22 of the screw type extrusion molding machine 20. The charged molding material is pushed out to the vacuum chamber 25 through the gap between the upper screw 24 and the upper barrel portion 23 by the rotation of the upper screw 24. The molding material extruded into the vacuum chamber 25 is decompressed by a vacuum pump connected to the vacuum chamber 25 and discharges bubbles inside the molding material. After that, by rotating the lower screw 27, it is pushed out through the gap between the lower screw 27 and the lower barrel 26 in the direction of the mold 28, and passes through the outlet portion 28a of the mold 28, thereby corresponding to the outlet shape. A rod-shaped molded body having a specific cross-sectional shape is obtained.

  The rod-shaped molded body thus obtained is, for example, a rod-shaped noodle product when a molding material using flour and water is used. Moreover, when it is set as the molding material using ceramic powder, a binder, and water, it becomes a rod-shaped ceramic member by drying and baking the obtained rod-shaped molded object.

  However, according to the screw-type extrusion molding machine 20, it is possible to continuously form a rod-shaped molded body, but the obtained rod-shaped molded body has a problem that a variation in density is large in its cross section.

  That is, in the screw type extrusion molding machine 20, the extrusion pressure applied to the molding material is applied by the shearing action by the spiral convex portion 31 provided on the outer peripheral part of the lower screw 27. The extrusion pressure varies depending on the location, and the low-density part is the central part of the molding material (hereinafter simply referred to as “connecting the screw tip part 27a on the extension of the axis of the lower screw 27) and the outlet part 28a of the mold 28” A phenomenon that makes it easier to concentrate on the center part) occurs. For this reason, density variation occurs inside the obtained rod-shaped molded body, the density of the central portion becomes extremely low, creating a cavity inside, and deformation or cracking during drying or firing of the rod-shaped molded body. There was a problem that occurred.

  In addition, the rotation of the lower screw 27 causes a flow in the rotational direction of the molding material, and the rod-shaped molded body thus obtained is twisted and deformed by passing through the outlet portion 28a of the mold 28 as it is. there were.

In order to solve these problems, Patent Document 1 includes a cylindrical rectifying unit for adjusting the flow of the molding material between the lower screw 27 and the mold 28, and a plurality of flows connecting the inlet and the outlet in the rectifying unit. A flow path is formed to divide the flow of the molding material, and the molding material flowing into the central portion at the rectifying portion inlet is at the peripheral portion at the rectifying portion outlet, and the molding material flowing into the peripheral portion at the rectifying portion inlet is centered at the rectifying portion outlet. The extrusion machine which changes to each part is disclosed. According to this extrusion molding machine, since the molding material can be mixed without difficulty in the barrel, variation in density is reduced, and a rod-shaped molded body having high strength and less deformation, warping, and cracking is obtained.
Japanese Unexamined Patent Publication No. 2006-103072

  However, since the resistance to the flow of the molding material in the cylindrical rectifying unit becomes extremely large, the extruder disclosed in Patent Document 1 cannot be used in a small-sized extruder with a small extrusion pressure.

  Further, in the cylindrical rectifying unit, the molding material is completely separated into a plurality of flow paths, so that the molding material separated even at the rear of the cylindrical rectifying unit cannot be completely integrated and obtained. There was a problem that linear flaws occurred on the surface of the rod-shaped molded body.

  Moreover, since the structure of the cylindrical rectifying unit is complicated, there are problems that the production cost of the extrusion molding machine is increased, maintenance is difficult, and the efficiency of the molding operation is deteriorated.

  The present invention has been devised to solve the above-described problems, and has a through hole non-formation region so as to cover the outlet portion of the mold as viewed from the screw tip without using the cylindrical rectification portion. An object of the present invention is to provide a screw-type extrusion molding machine for obtaining a rod-shaped molded body with little variation in the above.

  The screw-type extrusion molding machine of the present invention is provided with a plate-like body having a plurality of through holes between a screw tip portion and a die outlet portion, and the plate-like body is viewed from the screw tip portion. And a through-hole non-formation region is provided so as to cover the outlet portion.

  The screw type extrusion molding machine of the present invention is characterized in that, in the above configuration, the through hole is formed at an angle with respect to the extrusion direction of the molding material.

  Furthermore, the screw-type extrusion molding machine of the present invention is characterized in that, in the above-described configuration, a conical raised portion is provided in the through hole non-forming region of the plate-like body.

  According to the screw-type extrusion molding machine of the present invention, a plate-like body having a plurality of through holes is provided between the screw tip portion and the outlet portion of the mold, and the plate-like body is viewed from the screw tip portion. By providing the non-through-hole formation region so as to cover the outlet portion, the low density portion of the central portion of the molding material connecting the screw tip portion on the extension line of the screw shaft center and the outlet portion of the mold is once By dispersing so as to be pushed away from the central part in the outer peripheral direction, the concentration of the low density part in the central part is relieved, so the obtained rod-shaped molded body has a small variation in density and generation of cavities inside. In addition, there are few deformations and cracks when the rod-shaped molded body is dried or fired. Furthermore, since the structure is simple and the number of parts is small, the production cost of the screw-type extruder can be kept low, the maintenance is easy, and the molding efficiency is improved.

  Further, according to the screw type extrusion molding machine of the present invention, since the plate-like body is provided with a plurality of through holes, since the resistance when the molding material passes through the plate-like body is small, the extrusion pressure is low. Even in a small and small screw-type extruder, it is possible to obtain a rod-shaped molded body with little variation in density.

  Furthermore, according to the screw-type extrusion molding machine of the present invention, when the through hole is formed at an angle with respect to the extrusion direction of the molding material, it goes from the peripheral part to the central axis direction of the screw at the rear stage part of the plate-like body. By causing the flow of the molding material, the clogging of the molding material in the central portion of the rod-shaped molded body is improved, and it becomes possible to obtain a rod-shaped molded body with less variation in density. Alternatively, when the molding material passes through the through-hole, it is possible to suppress the flow in the rotation direction of the molding material by giving a flow in the direction opposite to the rotation direction of the screw, and the screw-type extrusion molding of the present invention. If it shape | molds using a machine, it can reduce that the extruded rod-shaped molded object is twisted and deform | transformed.

  Furthermore, according to the screw type extrusion molding machine of the present invention, when the conical ridge is provided in the through hole non-formation region of the plate-like body, the flow of the molding material before and after the plate-like body is further improved. Furthermore, the pressure variation in the screw-type extrusion molding machine is eliminated, and the variation in the density of the obtained rod-shaped molded body is reduced. Further, since the resistance when the molding material passes through the plate-like body becomes smaller, it is possible to obtain a rod-like molded body with little variation in density even in a small screw type extruder with a small extrusion pressure.

  Hereinafter, the best mode for carrying out the present invention will be described.

  FIG. 1 shows an example of an embodiment of a screw-type extruder according to the present invention, (a) is a schematic cross-sectional view, and (b) is a view of a mold from a screw tip of a lower screw in (a). It is an expanded sectional view when seeing the direction of an exit part.

  The screw-type extruder 1 shown in FIG. 1 has a vacuum chamber 5 between an upper screw 4 and a lower screw 7, and the upper screw 4 covers the upper barrel 3 and the lower screw 7 covers the lower barrel 6. It has been broken. Further, a molding material inlet 2 is opened in a part of the upper barrel 3, and a mold 8 is connected to the outlet side of the lower barrel 6. Here, the screw-type extrusion molding machine 1 refers to an apparatus in which the extrusion molding machine and the mold 8 are combined.

  Furthermore, the upper stage screw 4 and the lower stage screw 7 are formed with a spiral convex portion 12, one of which is connected and fixed to the upper stage bearing 10 and the lower stage bearing 11 and connected to a power source (not shown). The vacuum chamber 5 is connected to a vacuum pump (not shown) for evacuating the inside of the vacuum chamber 5.

  Next, a procedure for forming, for example, a ceramic rod-shaped molded body using the screw-type extruder 1 will be described.

  First, ceramic powder, a binder, and water are mixed with a mixing and stirring mixer, and further passed through a three-roll kneader three times to knead to obtain a clay-like molding material. Then, this molding material is charged from the charging port 2 of the screw type extrusion molding machine 1. The input molding material is pushed out to the vacuum chamber 5 through the gap between the upper screw 4 and the upper barrel 3 while being sheared by the convex portion 12 by the rotation of the upper screw 4. The molding material extruded into the vacuum chamber 5 is decompressed by a vacuum pump connected to the vacuum chamber 5 to discharge bubbles inside the molding material, and then sheared to the convex portion 12 by the rotation of the lower screw 7. However, it is pushed out in the direction of the mold 8 through the gap between the lower screw 7 and the lower barrel 6, and passes through the outlet 8 a of the mold 8, thereby forming a rod-shaped molded body.

  In the case of extrusion using such a screw-type extrusion molding machine 1, the extrusion pressure applied to the molding material is applied by the shearing action of the spiral convex portion 12 provided on the outer peripheral portion of the lower screw 7. However, there is a variation in the extrusion pressure due to this shearing action, and the low density portion of the extruded molding material is the screw tip portion 7 a on the extension of the axis of the lower screw 7 and the outlet portion of the mold 8. A phenomenon of concentration at the center of the molding material connecting 8a occurs.

  If the density of the central portion is low, there arises a problem that cracks and deformation occur in the rod-shaped molded body due to variations in shrinkage during drying and firing. Moreover, since the density of the central portion becomes extremely low, a cavity is formed inside the rod-shaped molded body, or the central portion is not densified at the time of firing, resulting in problems such as failure.

  Therefore, the present inventor has made various studies so as to obtain a rod-shaped molded body with less variation in density. As a result, as shown in FIG. 1, the present inventor is provided between the screw tip portion 7a and the outlet portion 8a of the mold 8. A plate-like body 9 having a plurality of through-holes 9a is provided, and a screw-type non-through-hole forming region 9b is provided on the plate-like body 9 so as to cover the outlet 8a of the mold 8 when viewed from the screw tip 7a. It has been found that the extrusion molding machine 1 can provide a rod-shaped molded body in which no voids are formed in the molded rod-shaped molded body and deformation and cracks are less likely to occur during drying and firing.

  This is because the low-density portion concentrated in the central portion of the molding material is once dispersed from the central portion toward the outer periphery by the through-hole non-forming region 9b provided in the plate-like body 9, and then the mold 8 By being pressure-filled again while being pushed out in the direction of the outlet portion 8a, variation in density between the central portion and the peripheral portion is reduced, and then passes through the outlet portion 8a of the mold 8 to form a rod-shaped molded body. Therefore, the obtained rod-shaped molded product has less variation in density between the central portion and the outer peripheral portion, and the molded rod-shaped molded product is not subject to internal cavities, deformation or cracking during drying or firing. By becoming a thing.

  Here, the through hole non-forming region 9b is provided so as to cover the outlet portion 8a of the mold 8 when viewed from the screw tip portion 7a side, so that the outlet portion 8a of the mold 8 is viewed from the screw tip portion 7a side. If it is not covered with the through-hole non-forming region 9b, the low density portion concentrated in the central portion of the molding material is not completely dispersed in the outer peripheral direction by the through-hole non-forming region 9b, and a part of As it passes through the outlet 8a of the mold 8 as it is and becomes a rod-shaped molded body, the obtained rod-shaped molded body has a large variation in density, and the molded rod-shaped molded body has internal cavities, during drying and firing. This is because deformation and cracks occur.

  Therefore, a plate-like body 9 having a plurality of through-holes 9a is provided between the screw tip portion 7a and the outlet portion 8a of the die 8, and the outlet of the die 8 when viewed from the screw tip portion 7a is provided in the plate-like body 9. If the screw-type extrusion molding machine 1 provided with the through-hole non-forming region 9b so as to cover the portion 8a is used, there is no cavity inside the molded rod-shaped molded body, and deformation and cracks occur during drying and firing. Therefore, the screw-type extrusion molding machine 1 having a simple structure and excellent cost and maintenance can be provided. Moreover, the obtained rod-shaped molded body is excellent in mass productivity and low in cost.

  At this time, it is important that the area of the through-hole non-forming region 9b is larger than the area of the outlet portion 8a of the mold 8, but if it is too large, the resistance when the molding material passes through the plate-like body 9 is increased. Since the molding with the small screw type extruder 1 having a small extrusion pressure becomes difficult, the area of the through-hole non-forming region 9b is not perpendicular to the axial direction of the lower screw 7 of the lower barrel 6. It is desirable that it is 50% or less with respect to the area. Further, the shape of the through-hole non-forming region 9b is preferably a substantially circular shape from the viewpoint of the uniform flow of the molding material, but there is no practical problem even if it has other shapes.

  In addition, since the through hole 9a is formed in a plurality of parts, a mixing and stirring action works when the molding material passes through the through hole 9a of the plate-like body 9, so that the obtained rod-like molded body has a variation in density. Becomes smaller. For this reason, it is better that the number of through holes 9a is larger in a range where the opening area is 30% or more with respect to the cross-sectional area perpendicular to the axial direction of the lower screw 7 of the lower barrel 6. However, if the opening area of the through hole 9a is less than 30% with respect to the cross-sectional area perpendicular to the axial direction of the lower screw 7 of the lower barrel 6, the resistance when the molding material passes through the plate-like body 9 is large. Therefore, it is difficult to form with a small screw type extruder 1 having a small extrusion pressure, which is not preferable.

  The screw type extrusion molding machine 1 has various sizes, and may be appropriately selected according to the desired size of the rod-shaped molded body. However, in consideration of mass productivity and maintainability, A diameter of about 30 mm to 200 mm is suitable.

  The screw-type extruder 1 of the present invention is an enlarged cross-sectional view of an example of the plate-like body 9 in the screw-type extruder as shown in FIG. 2A, and FIG. As shown in the enlarged cross-sectional view when viewing the outlet portion, it is preferable to use a plate-like body 9 in which a plurality of through holes 9a are formed at an angle with respect to the extrusion direction of the molding material. For example, as shown in FIG. 2A, by forming the through hole 9a at an angle from the outer peripheral portion toward the central axis direction of the screw, the molding once dispersed in the outer peripheral direction by the through hole non-forming region 9b. Since the material easily collects in the central part again, it becomes easier to press-fill the molding material in the central part, resulting in less variation in the density of the rod-shaped molded body, less generation of internal cavities, and when drying And less deformation and cracking during firing. Alternatively, as shown in FIG. 2B, when the molding material passes through the through hole 9a, the through hole 9a is formed at an angle so as to give a flow in a direction opposite to the rotational direction of the screw. It becomes possible to suppress the flow of the material in the rotation direction, and to reduce the twisting and deformation of the rod-shaped molded body.

  Furthermore, the screw-type extruder 1 of the present invention is a plate-shaped body as shown in an enlarged sectional view of the plate-shaped body 9 shown in FIG. 3 as another example of the plate-shaped body 9 in the screw-type extruder. It is preferable to provide a conical raised portion 9c in the 9 through-hole non-forming region 9b. By doing so, the molding material is not retained by the through-hole non-forming region 9b of the plate-like body 9, so that the flow of the molding material before and after the plate-like body 9 is further improved, and the screw-type extruder 1 The dispersion of pressure inside is eliminated, the dispersion of density of the obtained rod-shaped molded body is reduced, the generation of internal cavities is further reduced, and a rod-shaped molded body with less deformation and cracks during drying and firing is obtained. It becomes possible. Moreover, since the flow of the molding material in the through-hole non-formation region 9b flows along the conical bulge portion 9c due to the conical shape of the bulge portion 9c, the resistance portion is reduced and the small size of the extrusion pressure is small. Also in the screw type extrusion molding machine 1, it is possible to obtain a rod-shaped molded body with little variation in density. At this time, it is desirable that the size of the conical raised portion 9c is substantially the same size as the through-hole non-forming region 9b from the viewpoint of reducing the retention of the molding material. Moreover, you may provide the cone-shaped protruding part 9c in both the front and back of the plate-shaped body 9, or any one. In addition, the cone shape here means a shape close to a cone, and there is no problem even if it is a polygonal pyramid shape or a shape whose ridgeline is a curve.

  For example, if the molding material is mixed and kneaded with wheat flour and water to form a molding material, the resulting rod-shaped molded body is dried to a required moisture content to form a rod-shaped material such as udon or spaghetti. Since there is little variation in density, there is little deformation or breakage during drying, and a low-cost dry noodle product excellent in yield can be produced.

  Further, if a thermosetting resin is used as a molding material, the obtained rod-shaped molded body is subjected to a heat treatment necessary for the resin to be cured, and as a rod-shaped resin member, for example, for an electronic device. It can be used as an insulating member.

  Further, as a manufacturing method for obtaining a rod-shaped ceramic member, a molding material is prepared by mixing ceramic powder, a binder, and additives such as water, a plasticizer, and a dispersant, and the molding material is used as a screw type of the present invention. The extrusion molding machine 1 is used to extrude from the mold 8 to form a rod-shaped molded body, and the obtained rod-shaped molded body is dried and fired in an appropriate firing furnace.

  In this case, as the ceramic powder, alumina, zirconia, silicon nitride, silicon carbide, aluminum nitride, ferrite, cordierite, etc. are appropriately selected according to the purpose of use, and silicon oxide, calcium oxide, magnesium oxide are used as necessary. Sintering aids such as nickel oxide, zinc oxide and copper oxide may be added. In addition, as a binder, considering the flowability at the time of extrusion molding, the shape retention of the molded body, the strength of the molded body, and the handling property, it is preferable to use a cellulose-related binder, and among these, a water-soluble cellulose ether is used. It is preferred to use.

  The molding material inside the screw-type extruder 1 is subjected to frictional heat because it receives shearing forces generated between the upper screw 4 and the upper barrel 3 and between the lower screw 7 and the lower barrel 6. The temperature rises. Depending on the molding material, the fluidity deteriorates or the characteristics deteriorate due to the temperature rise due to this frictional heat, so that the jacket portion and the screw interior of the screw-type extruder 1 can be cooled with cooling water. It is preferable.

The molding procedure for obtaining the rod-shaped ceramic member by the screw-type extruder 1 of the present invention is as follows. First, the ceramic powder, the binder, and water are mixed with a mixing and stirring mixer, and further mixed into a three-roll kneader. Knead and knead to obtain a clay-like molding material. At this time, the clay-shaped molding material after kneading is, for example, a flow tester CFT-500C type manufactured by Shimadzu Corporation, and set conditions of a pressure of 6 MPa, a temperature of 20 ° C., a mold diameter of 1 mm, and a mold length of 1 mm. It is good to adjust so that the measured value in may become a viscosity range of 1 × 10 ² to 1 × 10 ⁴ Pa · s.

  Then, this molding material is charged from the charging port 2 of the screw type extrusion molding machine 1. The charged molding material is pushed out to the vacuum chamber 5 through the gap between the upper screw 4 and the upper barrel 3 by the rotation of the upper screw 4. The molding material extruded into the vacuum chamber 5 is decompressed by a vacuum pump connected to the vacuum chamber 5 to discharge bubbles inside the molding material, and then the lower screw 7 and the lower barrel are rotated by the rotation of the lower screw 7. 6 is extruded in the direction of the mold 8 through the gap between the plate 6 and the plurality of through holes 9a of the plate-like body 9 and then passes through the outlet portion 8a of the mold 8 to obtain a rod-like molded body. It is done.

  And in order to dry this rod-shaped molded body, rapid drying may deform the rod-shaped molded body, so that natural drying may be performed. However, after natural drying for a certain period of time, a kerosene boiler is further dried. It is preferable to carry out a combination of drying in a drying chamber set at a room temperature of around 80 ° C.

  Next, baking is performed after drying a rod-shaped molded object. The firing temperature pattern varies depending on the ceramic powder used. For example, when alumina is used, the temperature is first raised from room temperature to a temperature of 300 to 500 ° C. over 2 to 6 hours, and then 1 to 4 hours. Thus, the binder contained in the rod-shaped molded body is burned out. Thereafter, the temperature is raised to a maximum temperature of 1400 to 1650 ° C. over 2 to 6 hours, a holding time of 1 to 4 hours is provided, and then gradually cooled to room temperature.

  The rod-shaped ceramic member thus obtained can be suitably used as an insulating member used for a thermal fuse, a breaker or the like that requires heat resistance and insulation.

  Examples of the screw type extruder 1 of the present invention will be described below.

(Example 1)
A rod-shaped ceramic member is manufactured using the screw-type extruder 1 of the present invention shown in FIG. 1 and the conventional screw-type extruder 20 shown in FIG. A comparative test was conducted to confirm whether there were few deformations and cracks that occurred during drying and firing. The outlet 8a of the mold 8 at this time was circular with a diameter of 5 mm.

  First, a molding material for extrusion molding was produced. As a raw material powder to be used, a commercially available alumina raw material having a purity of 99% and an average particle diameter of 1 μm was used. 100 parts by mass of this alumina raw material, 3 parts by mass of sintering aid, 100 parts by mass of alumina raw material, 4 parts by mass of water-soluble cellulose ether as a binder, 6 parts by mass of surfactant, and 8 parts by mass Were mixed in a commercially available mixing and stirring mixer. Next, this was passed through a three-roll kneader three times and kneaded to obtain a clay-like molding material.

  Next, this molding material was thrown in from the inlet 2 of the screw type extrusion molding machine 1 shown in FIG. 1 to perform extrusion molding.

  The inside of the upper barrel 3, the lower barrel 6 and the lower screw 7 of the screw-type extruder 1 has a water-cooled jacket structure, and the temperature of the molding material is circulated by circulating cooling water set to 10 ° C. or lower. The rise was prevented. Furthermore, the vacuum pump 5 was operated and molding was performed while the vacuum chamber 5 was evacuated.

  As the molding conditions of the screw-type extruders 1 and 20, the rotation speeds of the upper screw 4 and the lower screw 7 were adjusted so that the molding speed of the rod-shaped molded body was 8 to 12 m / min.

  The obtained rod-shaped compact was cut to a length of 10 cm immediately after molding, dried for 12 hours by natural drying, and then placed in a batch-type firing furnace and fired to form a rod-shaped ceramic. A member was obtained. The temperature pattern of firing at this time was raised from room temperature to 400 ° C. in the air in 3 hours, held for 2 hours, then raised to 1600 ° C. in 6 hours and then held for 2 hours. The temperature pattern was cooled to room temperature over time. 100 rod-shaped ceramic members were produced by each molding machine.

  The position for measuring the deformation amount of the obtained rod-shaped ceramic member is shown in FIG. As shown in FIG. 4, the rod-shaped ceramic member 50 is placed on a table (not shown) of a tool microscope, and the rod-shaped ceramic member 50 is confirmed by looking at the rod-shaped ceramic member 50 from an eyepiece having a dimension measurement scale of the tool microscope. The table was adjusted so that the line 51 fits both ends of the rod-shaped ceramic member 50, and the deformation amount H at the place where the deformation amount was the maximum was measured. Moreover, the presence or absence of the generation | occurrence | production of a crack was confirmed visually after processing with a penetrant flaw detection liquid. In addition, the central part of the length of the rod-shaped ceramic member was cut with a rotary cutting machine equipped with a diamond grindstone, and the cross section was observed with a binocular microscope with a magnification of 30 times. confirmed.

  As a result, the rod-shaped ceramic member formed using the screw-type extruder 1 of the present invention had a maximum deformation amount H of 0.9 mm, and the number of cracks generated was 2 out of 100. On the other hand, the rod-shaped ceramic member formed by using the conventional screw-type extruder 20 had a large maximum deformation amount H of 2.8 mm, and the number of cracks was as many as 8 out of 100.

  Further, the rod-shaped ceramic member formed by using the screw-type extruder 1 of the present invention had 0 of 100 internal cavities, whereas the conventional screw-type extruder 20 In the rod-shaped ceramic member formed using, the number of internal cavities was as high as 21 out of 100.

  Therefore, a plate-like body 9 having a plurality of through-holes 9a is provided between the screw tip portion 7a and the outlet portion 8a of the mold 8, and the plate-like body 9 has a metal plate as viewed from the screw tip portion 7a. The rod-shaped molded body obtained by the screw type extrusion molding machine 1 of the present invention in which the through-hole non-forming region 9b is provided so as to cover the outlet portion 8a of the mold 8 has little density variation, and therefore, the internal cavity It was confirmed that there was little generation and deformation and cracking during drying and firing were reduced.

  Furthermore, a rod-shaped ceramic member was produced by the same method as described above using the screw-type extruder 1 of the present invention shown in FIG. At that time, the optimum range of the opening area of the plurality of through holes 9a was confirmed using the plate-like body 9 shown in FIG. 1B in which the areas of the plurality of through holes 9a were changed.

  As a result, when the opening area of the plurality of through holes 9a is 30% or more with respect to the cross-sectional area perpendicular to the axial direction of the lower screw 7 of the lower barrel 6, a rod-shaped molded body by extrusion molding can be obtained without problems. However, when the opening area of the plurality of through-holes 9a is less than 30% with respect to the cross-sectional area perpendicular to the axial direction of the lower screw 7 of the lower barrel 6, the plate shape with respect to the extrusion pressure of the lower screw 7 Since the resistance of the body 9 is large, a phenomenon in which the molding speed is extremely reduced was observed.

  Furthermore, when the opening area of the plurality of through holes 9a is less than 20% with respect to the cross-sectional area perpendicular to the axial direction of the lower screw 7 of the lower barrel 6, the resistance of the plate-like body 9 to the molding material is further increased. Since it becomes large, it becomes difficult for the lower screw 7 to extrude the molding material from the outlet portion 8a of the mold 8, and a good rod-shaped molded body could not be obtained.

  Accordingly, the opening area of the plurality of through holes 9a is preferably 20% or more with respect to the cross-sectional area perpendicular to the axial direction of the lower screw 7 of the lower barrel 6, and more preferably the plurality of through holes. It was confirmed that the opening area of 9a is preferably 30% or more with respect to the cross-sectional area in the axial direction of the lower screw 7 of the lower barrel 6.

(Example 2)
Next, as shown in FIG. 2 (b), when the molding material passes through the through-hole 9a, the through-hole 9a is formed at an angle so as to give a flow in the direction opposite to the rotational direction of the screw. A rod-shaped ceramic member was produced in the same manner as in Example 1 by using a screw-type extruder 1 and a conventional screw-type extruder 20. At this time, the outlet portion 8a of the mold 8 was a square having a side of 5 mm, and 20 rod-shaped ceramic members were cut to a length of 10 mm by a rotary cutting machine equipped with a diamond grindstone to produce 20 pieces. In this rod-shaped ceramic member, when the outlet portion 8a of the mold 8 is thus a square having a side of 5 mm, the rod-shaped molded body 18 is a prism.

  FIG. 5 shows a state in which the obtained rod-shaped ceramic member is extruded from the outlet portion 8a of the mold 8 as a prismatic rod-shaped formed body 18 in this case. As the molding material passes through the outlet portion 8a of the mold 8, as shown in FIG. 5, the rod-shaped molded body 18 of the rectangular column formed in the rotation direction of the lower screw (right rotation in the extrusion direction in FIG. 5) also rotates. Because it is pushed out, it twists and deforms.

  FIG. 6 shows a position at which the twisted and deformed angle of the rod-shaped ceramic member obtained by firing the twisted and deformed prismatic rod-shaped molded body 18 is measured.

  FIG. 6 shows a cross-section of the rod-shaped ceramic member as seen from the same direction as seen from the direction of the arrow in FIG.

  Next, the twisted and deformed angle of the obtained rod-shaped ceramic member 60 is measured by a projector with an angle measuring function, with the rod-shaped ceramic member 60 standing on a table (not shown) in the length direction of 10 mm. First, the table is adjusted after focusing on one side 63 of the bottom surface portion of the rod-shaped ceramic member 60, and the one side 63 of the bottom surface portion of the rod-shaped ceramic member 60 is aligned with the reference cursor 62 written on the screen. Next, after focusing on one side 64 of the upper surface of the rod-shaped ceramic member 60, the reference cursor is rotated so as to match the one side 64 of the upper surface of the rod-shaped ceramic member 60, and the rod-shaped ceramic member 60 is twisted and deformed. Measurements were made.

  As a result, when the molding material passes through the through hole 9a, the screw type of the present invention provided with the plate-like body 9 formed with the through hole 9a at an angle so as to give a flow in the direction opposite to the rotational direction of the screw. The angle S at which the rod-shaped ceramic member 60 is twisted and deformed when the extruder 1 is used is as small as 0 to 0.2 degrees, whereas the rod-shaped ceramic member 60 when the conventional screw-type extruder 20 is used. The angle S that was twisted and deformed was as large as 0.3 to 0.8 degrees.

(Example 3)
Next, as shown in FIG. 3, the screw-type extruder 1 of the present invention in which a conical raised portion 9c is provided in the through-hole non-forming region 9b of the plate-like body 9 is used in Examples 1 and 2. A rod-shaped ceramic member was prepared in the same manner as described above, and a test was performed to confirm whether the obtained rod-shaped ceramic member has few deformations, cracks, and internal defects.

  As a result, the maximum amount of deformation H of the obtained rod-shaped ceramic member was 0.5 mm, and the number of cracks generated was 1 in 100. The number of internal cavities was 0 out of 100.

  From this, the rod-shaped molded body obtained by using the screw-type extrusion molding machine 1 of the present invention in which the conical raised portion 9c is provided in the through-hole non-forming region 9b of the plate-shaped body 9 further has a variation in density. It was confirmed that there was little generation of internal cavities, and deformation and cracks during drying and firing were further reduced.

  Further, since the resistance when the molding material passes through the plate-like body 9 is small, it was confirmed that a compact with little variation in density can be obtained even in the small extrusion molding machine 1 having a small extrusion pressure.

An example of embodiment of the screw type extrusion molding machine of the present invention is shown, (a) is a schematic sectional view, (b) is a view when the direction from the screw tip part in (a) to the exit part of the mold is seen. It is an expanded sectional view. An example of the plate-shaped body in the screw-type extrusion molding machine of the present invention is shown, (a) is an enlarged cross-sectional view of the plate-shaped body, (b) is an enlarged cross-section when the outlet portion of the mold is viewed from the screw tip. FIG. It is an expanded sectional view of a plate-like object showing another example of a plate-like object in the screw type extrusion molding machine of the present invention. It is a figure which shows the position which measures the deformation amount of the rod-shaped ceramic member of this invention. It is a perspective view which shows the state which a rod-shaped molded object is twisted and extruded from a metal mold | die. It is a figure which shows the position which measures the angle which the rod-shaped ceramic member of this invention twisted and deform | transformed. It is a schematic sectional drawing which shows an example of the conventional screw type extrusion molding machine.

Explanation of symbols

1: Extruder 2: Input port 3: Upper barrel 4: Upper screw 5: Vacuum chamber 6: Lower barrel 7: Lower screw 7a: Screw tip 8: Mold 8a: Outlet 9: Plate 9a: Through Hole 9b: Through hole non-formation region 9c: Raised portion
10: Upper bearing
11: Lower stage bearing
12: Convex

Claims (3)

A plate-like body having a plurality of through-holes is provided between the screw tip and the mold outlet, and the plate-like body is not provided with a through-hole so as to cover the outlet when viewed from the screw tip. A screw-type extruder having a forming region. The screw-type extruder according to claim 1, wherein the through hole is formed at an angle with respect to the extrusion direction of the molding material. The screw-type extruder according to claim 1 or 2, wherein a conical raised portion is provided in the through hole non-formation region of the plate-like body.

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