JPS6017659B2 - Machining method for ceramic molded bodies - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of machining a ceramic molded body of rock knot.

In recent years, ceramics have been used in electronic parts, precision mechanical parts, discharge lamp parts, etc., and there has been a demand for ceramics to have higher density and improved dimensional accuracy.

For this reason, efforts are being made to improve the density of ceramic molded bodies, improve the dimensional accuracy of molding molds, and make the firing shrinkage of ceramic molded bodies smaller and more uniform.

However, for items with strict dimensional accuracy, machining is performed on ceramic molded bodies or adjacent bodies, but since the latter is a dense, hard, and brittle body, the machining requires grinding using diamond grains. Since they are expensive, emphasis is placed on processing the former type of ceramic molded bodies as much as possible.

However, since substrate-shaped ceramic products have a two-dimensional shape, it is now possible to obtain products with relatively high dimensional accuracy and a small firing shrinkage rate using methods such as powder pressing and doctor blade methods. , rod-shaped, and tubular ceramic products are three-dimensional, and the molding methods are limited to extrusion and isostatic pressing methods. Therefore, molded products with good dimensional accuracy and uniform density, i.e., firing shrinkage. Uniform items are difficult to bind. For this reason, it is necessary to perform machining on rod-shaped and tubular ceramic molded bodies, and in the case of tubular molded bodies in particular, since they are molded to increase the accuracy of their inner dimensions, it is best to machine their outer sides. It's fast. Conventionally, the above-mentioned machining methods include cutting a ceramic molded body with a lathe or the like using a cutting tool made of metal ceramic or the like, or grinding using a grindstone such as a carbon random t-corundum type grindstone. However,
Since ceramic molded bodies are unscaled, their mechanical strength is low and dry processing is required, resulting in high wear of the cutting tool and grindstone, and the need for dressing due to clogging, especially for thin-walled products. It was extremely difficult to process the material without damaging it.

Therefore, in order to increase the mechanical strength of ceramic molded bodies, methods of temporarily solidifying by heat treatment or impregnating with paraffin (Hakama Kosumi No. 46-34085) have been proposed, but both require extra processing steps. And.

There is a risk that the ceramic molded body will be damaged during its handling, making it impossible to handle and expensive. The present invention has been made in order to eliminate these drawbacks, and is a method for machining a tubular molded body made of ceramic raw material powder. This is a method of machining ceramic molded bodies by rotating and machining them at a speed of 140 h or more.

That is, by limiting the abrasive grain size of the diamond bonded diamond wheel of the present invention and limiting the relative circumferential speed between the circumferential speed of the wheel and the circumferential speed of the ceramic compact, it is possible to efficiently manufacture a tubular compact with good dimensional accuracy and at low cost. It is specially machined.

The reason why diamond is used as the abrasive grain here is that when processing hard molded objects such as alumina ceramics using force-bond random materials, metals, etc., wear quickly and the processing efficiency is poor. This is because if the speed exceeds 100 rpm, particles will drop out more and the grinding ability will deteriorate in a short time, and if the speed is lower than 50 rpm, the amount of grinding will be small and the machining time will increase.

In addition, if the relative circumferential speed is less than 140 plates, not only will the grinding speed be low, but the grinding resistance will be large enough to damage the ceramic molded body or make the ground surface rough. This is because it has to be made smaller. Here, the relative circumferential speed is determined from the rotation speed of the general grinding machine and the holding and dimensional accuracy of the ceramic molded body.
It is desirable that the number of revolutions of the ceramic molded body is 50 PM or less, and the number of revolutions of the resin pond diamond wheel is 200 PM or less. The present invention will be explained below based on Examples. Using fine alumina powder with a particle size of 0.3 m as the main raw material, add a small amount of subcomponents such as magnesium oxide at 0.3% by weight, and after wet mixing in a ball mill for 24 hours ~ polyvinyl alcohol as a viscous agent. After adding 3% by weight and mixing, it is granulated with a spray dryer to make the water content 0.

A powder having a milk weight percent of 60 mesh or less was obtained. Next, a tubular molded product having an outer diameter of 12, an inner diameter of ◇10, and a length of 50 m was molded using this powder isostatic press machine with a focus of 10 m². The outer diameter of this tubular molded body was measured using a cylindrical grinding mold using a wheel made of resin-bonded diamond and cinnabar carbide abrasive grains shown in Table 2 under the conditions of relative circumference of 994 to 2204 degrees shown in Table 1. The wheels were processed to a dimensional accuracy of 0.012±0.02, and the number of processes that could be completed during one wheel dressing was investigated, and the results shown in FIG. 1 were obtained. Table 1'. As shown in FIG. 1, when the resin bond diamond wheel abrasive grain size and relative circumferential speed are within the range of the present invention, the number of wheels processed is 300 to 400, and when processed outside the range of the present invention, The number of processes was extremely superior compared to that of 70 to 90 mills.

As stated above, ``According to the method of the present invention, it is possible to efficiently process tubular molded bodies made of ceramic as raw materials without performing any special processing steps, and in particular, it is possible to process thin-walled articles such as arc tubes for discharge lamps. It is suitable for products that require dimensional accuracy, and will greatly contribute to the development of industry.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between the relative circumferential speed and the number of processes that can be performed in one dressing when the wheel abrasive grain diameter is used as a parameter. Figure 1

Claims (1)

[Claims] 1. A method for machining an unsintered tubular molded body of ceramic raw material powder, which comprises machining a resin bonded diamond wheel with abrasive grains of 50 to 100 μm at a relative circumferential speed of 1400 m/min or more. Machining method.