JPS629869A - Removing method of burr from aluminum or magnesium alloy cast - Google Patents

Abstract

PURPOSE:To enable a burr to be removed from an Al or an Mg alloy cast preventing its processed surface from flawing, by using Cu or Cu alloy dust in a spherical or almost spherical crystal shape of face-centered cubic lattice (fcc lattice) as a shot material to be shot. CONSTITUTION:The method, placing a work of Al of Mg alloy cast on a table or a conveyer or hanging the work from a hanger so as to be prevented from colliding with each other and transferring the work into a shot chamber, uses Cu or Cu dust alloy in a spherical or almost spherical crystal shape of face- centered cubic lattice (fcc lattice) as a shot material to be shot by a shot blast. The method, if it uses said dust alloy in a 40-300mum grain size to be shot at a speed of 30-70m/sec, perfectly removes a burr from the work and generates slight roundness in its edge part. And the method causes no change also in roughness of a machined surface while no generation of coloring in dark gray on the work as carbonized when an organic material is used.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for removing burrs generated on a machined surface of an aluminum or magnesium alloy casting.

(Prior art) Various methods have been used to remove burrs generated on the machined surface of castings, but the burrs generated during machining of aluminum or magnesium alloy castings can be removed by conventionally known methods. If you try to remove it, there is a risk of scratching the machined surface or making the surface rough, so it is usually done by hand using tools such as a grinder, file, router, band brush, etc. (Problem to be solved by the invention) However, these methods have low productivity due to manual finishing.There is also a special machine using a brush as an automation method to improve this productivity, but this special machine Although it is effective for removing burrs from the outer periphery of the workpiece, it is less effective for workpieces that have areas where the brush cannot reach, so special hand tools are created and several steps of brush work are done manually. There is also the problem that it has to be compensated for by processing.
In barrel polishing, in order to prevent dents caused by collisions between workpieces, even if the polishing machine is equipped with a partition tank, there is the problem that clogging of abrasive grains occurs, and the processing time is 10 minutes.
It takes ~15 minutes, so if you try to make it into a continuous line, the time pitch will not match the previous and previous processes, and on top of that, you will have to add processes such as separating the abrasive grains and the workpiece, washing, drying, etc. -There is a problem that it is difficult to form a consistent line. Furthermore, the method of deburring by bombarding high-pressure water is good for simply finishing the edges of machined surfaces, but there is a problem that it becomes difficult to remove burrs when the thickness of the burrs exceeds about 0.1 days. The problem with the injection processing method using shot is that the glass shot is hard and breaks during processing, resulting in sharp edges, which only roughens the machined surface and is not effective for deburring.

(Means for Solving the Problems) The method for removing burrs from aluminum or magnesium alloy castings of the present invention has been made to eliminate the above-mentioned problems. Or Cu or C that is approximately spherical and has a face-centered cubic lattice crystal shape.
This method is characterized by projecting the u-alloy powder at a projecting speed of 30 to 70 m/see.

In the present invention, the machined aluminum or magnesium alloy castings are first placed on a rotary table, hung on a hanger, or placed on a conveyor to prevent the workpieces from colliding with each other. Move indoors.

A centrifugal projection device or an air jet projection device is provided in the projection chamber, and the projection device impacts the fine projection material onto the burr-generating portion of the workpiece. When the shot material is projected in this way, the machining burrs that are generated on the workpiece are cut off by the dynamic impact, and the edges after the burrs are removed are slightly rounded. , when the prescribed projection is completed, the workpiece is transferred from the projection chamber to the outside, while the shot material is automatically separated and collected from the projection chamber, which is different from the conventional deburring method using the projection method. Although not subject to change, the reasons for the limitations in the present invention are as follows.

The quality of the work result for removing burrs generated on the machined surface of aluminum or magnesium alloy castings without roughening the machined surface is influenced by the material, shape, average particle size of the projectile, and impact pressure against the workpiece. . In general, it is contradictory to remove burrs generated by impacting a certain material without changing the roughness of the machined surface of soft metals such as aluminum or magnesium alloy castings. Elastic organic non-metallic blasting materials such as rubber and plastic do not roughen the machined surface, but the elasticity of the blasting materials absorbs kinetic energy, which not only makes it useless for deburring, but also absorbs it upon impact. The heat generated by the energy carbonizes the conveyed material and colors the workpiece blackish-gray, making it impossible to use organic material-based projectile materials, and oxide-based projectile materials have high hardness. If the particles are coarse, the machined surface of the workpiece will become matte, so it cannot be used, and if the particles are fine, it cannot be used because it cannot be deburred.
Furthermore, a projectile material for removing machining burrs from soft metals such as aluminum or magnesium alloy castings requires a certain mass or more and plasticity that allows distortion or deformation.

Fe, ZnSPb are substances that meet these conditions.
.

There is Cu and its alloys. However, PB cannot be used because it is harmful to the human body, and Fe has a high hardness depending on the amount of carbon it contains, and satisfactory results cannot be obtained unless it is close to pure iron with less carbon. Moreover, the fine powder generated during projection remains on the surface of the workpiece, which tends to cause the dotted line phenomenon, so it cannot be used.Also, although Zn shows good values in terms of mechanical properties, When compared with spherical Cu powder of the same diameter and hardness, it roughens the machined surface of the casting. This seems to be because the crystal lattice of Zn is a close-packed hexagonal crystal lattice, whereas the crystal lattice of Cu is a cubic crystal with equiaxed planes. For this reason, Znn shot cannot be used. On the other hand, shot materials made of Cu and its alloys have excellent properties such as mass, strain and thermal conductivity, and have the advantage of being easy to produce spherical powder with a desirable shape. be. The flat Cu powder and the 01 alloy powder are uneconomical because they are slowed down by air resistance during projection and are easily sucked into the dust collector, resulting in a large amount of the powder being lost. Naturally, the larger the particle size of the shot material of Cu and its alloys, the greater the deburring effect, but there is a limit to maintaining the machined surface roughness, and if the average particle size is less than 4 Opm, the deburring effect is too small to be used. If it exceeds 300 μm, it cannot be used because the shot surface of the workpiece will be roughened by the shot material, and the contact pressure of the Cu and its alloy shot material to the workpiece is determined by the velocity of the shot material at the time of collision of the shot material. Expressed in terms of , a speed of at least 30 m/sec is required to remove burrs from a machined surface, and the maximum projection speed must be kept below 70 m/sec to prevent roughening of the machined surface.

(Function) According to the method for removing burrs from aluminum or magnesium alloy castings of the present invention, machined aluminum or magnesium alloy castings are removed using a rotary table, hanger, or conveyor to prevent workpieces from colliding with each other. Cu or Cu having an average particle size of 40 to 300 μm, spherical or nearly spherical shape, and face-centered cubic lattice crystal shape is transferred to the projection chamber, and from a centrifugal projection device or an air injection projection device in the projection chamber. The alloy powder is impactfully projected onto the burr-generating part of the workpiece at a projection speed of 30 to 7 Q m/sec, and the machining burrs that had been generated on the workpiece are cut off by the dynamic impact. After the burr is removed, the edges are slightly rounded.

(Example) Example 1 A 47257-part milled aluminum alloy die-casting pulp body was placed in a table-type air blast device, and a blasting material of spherical Cu powder with an average particle size of 150 μm was blasted at a blasting speed of 60 m+/secC. When 100 kg was projected on the material, all the 0.08 tm thick burrs generated during milling were removed, and the surface roughness was as low as Rz 2.8μ of the material.
m could be maintained as is.

Example 2 A computer part made of a milled aluminum alloy die-casting was placed in a table-type air blasting device, and 4 shots of spherical Cu powder with an average particle size of 250 peg were shot at a shooting speed of 30 s/see. As a result, the sharp edges caused by milling were removed, and a rounded part with a radius of 0.06 was created at the edge. The surface roughness of the processed surface was RZ3.0 μm, which was almost the same as before projection.

Example 3 A milled magnesium alloy die-cast automobile part was placed in an air blast device, and 2 kg of spherical Cu alloy powder with an average particle size of 80 μm was projected at a projection speed of 65 eC. The 0.06 tm thick burr generated during milling is removed and the edges are 0.06 tm thick.
．． It has a rounded part of 05W. The surface roughness of the machined surface is Rz2
．． There was almost no difference between the 5μ and before injection.

(Effects of the Invention) As is clear from the above description, the present invention has the advantage that burrs generated on the machined surface can be removed without roughening the machined surface, and that it can be automated by matching the working time pitch with other processes. The projectile material to be used has excellent properties such as mass, amount of strain, and thermal conductivity, and it is easy to produce spherical powder with a desirable shape, and there is no deceleration due to air resistance when projecting.
Separation and recovery can be performed automatically from the projection chamber, and the workpiece will not be carbonized and colored black-gray like existing materials, and the fine powder generated during projection will not be on the surface of the workpiece. Coupled with the advantage that it does not remain behind and cause the dotted line phenomenon, the present invention greatly contributes to the development of industry.

Claims (1)

[Claims] A burr for aluminum or magnesium alloy castings characterized by projecting Cu or Cu alloy powder having a spherical or substantially spherical crystal shape with an average particle size of 40 to 300 μm and a face-centered cubic lattice at a projecting speed of 30 to 70 m/sec. How to remove.