JP3235032B2 - Method for manufacturing ceramic molded body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing ceramics and molded articles, and more particularly to a method for extruding ceramics having a honeycomb structure having a rectangular cross section.

[0002]

2. Description of the Related Art Conventionally, a ceramic formed body having a honeycomb structure having a rectangular cell cross section has been used as an exhaust gas purifying apparatus for a diesel engine. That is, a honeycomb structure is formed by a large number of through-holes (cells) partitioned by thin partition walls, and one end face of the through-hole is closed in a checkered pattern, and the remaining open through-holes have other end faces. The sealing and exhaust gas are introduced through a through-hole opened on one end face, discharged through a hole opened on the other end face through the partition wall, and the fine carbon particles are collected in the partition wall. And
This ceramic molded body is usually molded by an extrusion molding method, and the molded body continuously extruded from a die provided at the exit end of the extruder is cut into desired dimensions using a piano wire, and then fired. Being manufactured.

However, when an extruded product is cut with a piano wire, the cut surface is coarse and the dimensional accuracy is poor.
Secondary processing such as press molding is performed again. In this case, the rough cut surface is subjected to re-cutting processing prior to the secondary processing, and at that time, cut chips are generated. Therefore, such a method is not economical because not only the processing chips are generated but also many processing operations are required.

Further, when a thin cell wall having a cell wall thickness of 0.2 μm or less is cut with a piano wire, a piano wire having a thickness of about 50 μm which is close to the critical thickness of the piano wire is selected. As a result, the object to be cut is deformed because the strength of the object to be cut is low, and the piano wire itself is disconnected due to damage due to friction with the surface to be cut. As a result, the thickness of the piano wire is practically limited to a range in which the wire is not broken because the productivity is reduced and the defect rate is increased.

[0005] The cut surface of the honeycomb formed body having a thin cell structure by a piano wire must be cut again after drying a length of several mm to several tens of mm or after firing. For example, when the product length is 100 mm, if the both end faces are cut again by 10 mm each, the generation of the above-mentioned cutting waste alone will generate a defective generation amount of nearly 20%.

[0006]

The present inventors have made various studies to solve these problems, and as a result, have completed the present invention. An object of the present invention is to improve the strength of an extruded article having a honeycomb structure. An object of the present invention is to provide a method for manufacturing a ceramic molded body by using a cutting method in which a cut end surface of a workpiece having a small cutting edge is not deformed.

[0007]

SUMMARY OF THE INVENTION The gist of the present invention is to use a honeycomb-shaped ceramic body having a rectangular cell cross-sectional shape and a double-sided steel sheet having a thickness of 0.01 mm to 0.5 mm. And cutting the ceramic molded body in a direction perpendicular to the extrusion direction from the ridge line of the two surfaces of the ceramic molded body extruded. That is, the present invention uses a double-sided blade steel having a specific thickness, and is perpendicular to the extrusion direction from the ridge line of the two surfaces of the object to be cut and 5 ° to the surface formed by extrusion. By cutting at an angle of up to 45 °, the honeycomb structure can be prevented from being broken, and the secondary processing step can be omitted.

In the present invention, the blade to be cut is a double-sided blade steel having a thickness of 0.01 mm to 0.5 mm. When the thickness of the double-sided blade is more than 0.5 mm, the cut end face is distorted, and "hair cracks" are easily formed on the end face in a drying step and a firing step. It is not preferable because defects such as the density of the cut end surface becomes larger than those of other portions are generated. The use of a single-sided blade not only increases the risk of damage to the cut end surface due to the application of double frictional force compared to the case of using a double-sided blade on one cut end surface, but also shortens the life of the blade. The efficiency is poor.

The starting point of cutting in the present invention will be described. That is, the direction of the extrusion axis of the molded body extruded from the extrusion die of the extruder is referred to as “a-axis direction”, and a plane perpendicular to the “a-axis direction” is referred to as “b-plane”. The intersection of the surfaces formed by extrusion is called a ridgeline. Therefore, in the present invention, the cutting is started from the ridge line of the object to be cut, and the cutting is performed on the b-plane. As described above, cutting a formed body having a rectangular honeycomb structure with a cell having a quadrangular cross section perpendicular to the extrusion direction from the ridgeline and at an angle of 5 ° to 45 ° with respect to the surface formed by the extrusion molding is performed by extrusion. As compared with the case of cutting from the surface formed by molding, the stress at the time of cutting is relatively uniform, and when cutting with a sharp blade as in the present invention, there is no deformation near the cut surface. Processing) becomes unnecessary.

[0010]

Next, the present invention will be described with reference to examples. Example 1 9 parts by weight of methylcellulose, 4 parts by weight of a polyalkylene / glycol derivative-based lubricant, 2 parts by weight of glycerin and 2 parts by weight of water based on 100 parts by weight of silicon carbide powder.
Using a kneaded clay obtained by mixing and kneading 2 parts by weight, using a vacuum extrusion molding machine, at a degree of vacuum of 30 Torr, at an extrusion pressure of 60 kg / cm, at a molding speed of 400 m / m, the outer dimensions are 30 mm × 30 mm.
Square rod shape with a cell wall thickness of 0.3 mm and 200 cells /
A silicon carbide-based ceramic molded body was formed. This molded body was cut by a cutting machine set to have a length of 153 mm.

FIG. 1 shows the cutting state. In FIG. 1, a molded article 1, which is an object to be cut formed by a vacuum extrusion molding machine, is carried to a cutting machine by a conveyor belt 2. The object to be cut is a silicon carbide ceramic molded body having an outer dimension of 30 mm x 30 mm, a cell wall thickness of 0.3 mm, and a cell number of 200 cells / in. The cutting machine is installed obliquely upward with a 45 ° eccentricity. The cutting machine comprises an elevating device 6 having an electric cylinder 5, and is installed so that the double-sided blade 3 can be moved back and forth by a double-sided blade support bar 4 provided at the tip thereof. The thickness of the double-sided blade 3 is 0.1 mm and the width is 10
mm and a length of 10 mm. The lifting / lowering device 4 is an electric / cylinder with a lifting / lowering speed set to 25 cm / sec.
・ The system method is used. In this method, the object is cut twice by one reciprocating motion.

After cutting the object to be cut formed by the above vacuum extruder using this cutting apparatus, the obtained cut object is conditioned and dried at 80 ° C. for 5 hours, and then heated under an inert atmosphere. As a result of sintering at 2,200 ° C for 2 hours,
mm was obtained. Both end faces of the obtained sintered body were able to produce a honeycomb filter free from defects such as cracks and chips.

[0013]

As described above, according to the method of the present invention, the extruded body having a honeycomb structure having a small cell wall thickness, a small strength, and a poor shape-retaining property is subjected to secondary processing after drying or firing. Therefore, it is possible to prevent the generation of defective waste of expensive raw materials.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a cutting device for carrying out the present invention.

FIG. 2 is an explanatory diagram showing a cutting direction according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Workpiece 2 Workpiece transfer conveyor 3 Double-sided blade 4 Double-sided blade support bar 5 Electric cylinder 6 Lifting device

Claims (1)

(57) [Claims] An extruded ceramic molded body having a honeycomb structure having a rectangular cell cross section and a thickness of 0.01 mm.
Using a double-sided blade steel of 0.5 mm to 0.5 mm, the direction perpendicular to the extrusion direction from the ridge line of the two extruded surfaces of the ceramic molded body is 5 mm from the extruded surface.
A method for producing a ceramic molded body, comprising cutting at an angle of from 45 to 45 degrees.