JP2002011649A - Method for grinding by granular media - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing method by granular media capable of selectively polishing only a given surface and as a result, also reducing polishing consumption energy. SOLUTION: A method is provided that a work (a substance to be polished) having at least one surface being a surface to be polished (a surface to be ground) and provide at the periphery of the central part of the surface to be polished with a through-gap is polished by using granular media. A liquid storage part 86 consisting of a sedimentation layer 83 formed of granular media (polishing media) 82 and a supernatant layer 84 is formed in a polishing tank 14. After a work 16 is immersed in the supernatant layer 84 with a surface 16a to be polished positioned opposite to the sedimentation layer 83, a work 16 is rotated and floating fluid toward the surface 16a to be polished is generated at the granular media 82 to effect polishing (grinding) of the surface 16a to be polished.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a ground medium on which at least one surface is to be polished (ground surface) and which has a through-hole around the center of the polished surface. And a method and apparatus for polishing (grinding) by the method. In particular, it is a polishing method suitable for surface finishing (glossing and the like) of metal products such as wheels of automobiles and screws of ships.

Hereinafter, a method for polishing an aluminum wheel for automobiles (aluminum wheel) will be described mainly by way of example. However, the present invention is not limited to this method, and copper alloy products (for example, faucet fittings), ceramic molded products, It can also be suitably used for finishing plastic molded products and the like.

[0003]

BACKGROUND ART Finished aluminum wheels include glossy and semi-glossy products. For glossy products, there are cases where hard chrome plating is applied, and cases where glossy buff finish is followed by transparent coating. The present invention is mainly used for smooth finishing as a pre-process of plating glossy products and glossy buffing.

[0004] A semi-glossy product is usually completed by projecting a stainless steel cut wire to form fine irregularities on the surface, and then applying a gray coating similar to metal aluminum.

[0005] In the conventional finishing process of a glossy product, several processes are performed after machining a cast workpiece and then changing the buffing number.

For example, a low-pressure cast product having a poor casting surface is # 1.
20 → # 180 → # 240 → # 320 → Sisal buff,
High pressure castings with good casting surface are # 240 → # 320 → # 40
0 → Sisal buff and so on.

[0007] The design of aluminum wheels varies widely, and the type and number of buffs are changed depending on the location, and work is performed based on the experience and intuition of a skilled buffer. For this reason, even skilled workers could grind only a few complex designs a day. The wheel grinding industry is in a dark state ahead of the 3K work environment and the aging of buffers. On the other hand, the design of aluminum wheels has many free-form surfaces, and automation was not possible with many kinds and small lots.

In order to reduce the number of steps in the buffing operation, a method of mechanical polishing using granular media, barrel finishing, spin finishing, etc., which does not require any skill in the polishing operation, has been adopted.

However, instead of replacing the entire process with mechanical polishing, the number of processes is merely reduced. For example, in the case of a low casting, the process is # 180 → # 240 → # 320, and in the case of a high casting, # 240 → The buffing step of # 320 is mechanized.

At present, in the barrel finishing, a medium, a compound, water, and a work are put into a box-shaped polishing tank and polished by vibration.
It took more than 5 hours to polish from 0 to 100 μm. Method of using chemical polishing in combination to increase the polishing power (Japanese Patent Application No. Hei 8
-41410), but this method requires a polishing time of 1 hour.
Although it can be shortened to the extent, surface defects (recesses)
There was a risk that it would remain.

The above-mentioned spin finishing is a method in which a work is charged into a polishing tank and rotated, and there are two types of polishing methods, a wet type and a dry type. In the wet process, resin media is usually used (a mixture of resin and abrasive grains such as alumina and silica).
Then, a compound (brightening agent, cleaning agent, etc.) and water are added, and the work is rotated. In the dry method, for example, as a medium, a composite medium in which inorganic hulls are coated on the surface with inorganic ground particles and a crushed corn core such as walnut or a corn core is used as a core. The polishing tank is
Usually, it is a donut type, and the medium in the tank is moved by vibrating or flowing the tank. This is to reduce power consumption and allow the media to pass through the design window of the work (aluminum wheel).

The method of (1) has a larger abrasive force than the method (2), but the difference in the abrasive force between the outer peripheral portion, the central portion and the design window is large, and uneven wear is easily generated (the uneven wear is smaller). .

That is, in the spin finishing, since a work is rotated in a medium, a speed difference between an outer peripheral portion and a central portion (a relative speed difference with the medium) is large, and uniform polishing cannot be performed. In addition, the inside of the wheel design window is very poor (weak / small) through which the media passes, and there is a possibility that a large amount of unpolished portions may occur.

Further, in both of the above polishing finishes,
The rotation speed of the work is estimated to be 100 rpm or less, but the power consumption is considered to be extremely large due to the rotation in the medium.

The present invention has been made to solve the problems of the conventional polishing method, and provides a polishing method capable of greatly improving the polishing force and the uniformity of the polishing and reducing the driving power. is there.

Another object of the present invention is to provide a polishing method using a granular medium having a small initial power load when a workpiece is brought into contact (penetration) with the granular medium.

It is still another object of the present invention to provide a polishing method capable of polishing only a required surface of a work and consequently reducing the consumption of a medium.

[0018]

Means for Solving the Problems In the course of intensive research and development in order to solve the above-mentioned problems, the present inventors have conducted a study on a supernatant liquid containing a sedimentation layer composed of granular media and a supernatant layer. The work in the layer was rotated at a high speed (300 rpm or more) to generate a floating flow in the polishing medium, and it was examined whether or not the polishing could be performed.

At least one surface is a surface to be polished (surface to be polished), and an object to be polished (work) having a through-hole around the center of the surface to be polished is polished (ground) using a granular medium. In the method, a liquid storage section consisting of a sedimentation layer composed of granular media (polishing medium) and a supernatant layer is formed in a polishing tank, and a workpiece is immersed in the supernatant layer with the surface to be polished facing the precipitation layer. Thereafter, the workpiece is rotated to generate a floating flow in the granular media, thereby polishing the surface to be polished.

In the above structure, a cylindrical baffle (liquid flow guide cylinder) is disposed at a position above the surface to be polished and is directed toward the inside of the cylindrical baffle through a through space of the object to be polished. By generating the floating flow, the upward flowability (both speed and amount) of the granular media is increased.

Further, by disposing a plate-shaped baffle (baffle plate member) capable of forming a media discharge gap between the cylindrical baffle and the upper edge of the cylindrical baffle when the work is rotated,
The fluidity of the granular media is further increased.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 to 5 show an example of a polishing apparatus used in the polishing method of the present invention. Here, from the viewpoint of polishing efficiency,
Take an example of a polishing machine that can arrange two workpieces in parallel.
The same applies to a polishing apparatus in which one or three or more can be arranged symmetrically (for example, side by side, cross, staggered, etc.).

The polishing apparatus 12 includes a polishing tank 14 which can be moved up and down.
And a work rotating device 18 that can hold the work 16 and rotate at high speed.

The polishing tank 14 is provided on a bottom plate 20 with a flat rectangular frame 2 having flange portions 22a and 22b in two stages.
2 and 22 are formed by overlapping flanges with bolts or the like, and a lifting device (jack device) 24 is provided on the bottom surface side.
Is arranged. Further, the polishing tank 14 is usually provided with a lining layer 26 on the inner side to prevent abrasion.

Although the illustrated example has a two-stage structure from the viewpoint of light weight and cost, it is of course possible to form it integrally.

The lining layer 26 is usually formed by casting or baking polyurethane or abrasion-resistant rubber, and has a thickness of, for example, about 10 mm. The polishing tank for ordinary barrel polishing is under the load of the media and is subjected to vibration, flow, and other forces.On the other hand, the media floating in the water collides with the tank wall in the present invention. Wear is small because it is underwater.

Although not inevitable, an overflow port 28 is further provided on the upper end of the polishing layer 14 and on the rear side of the polishing layer 14.
With the drainage cover 3 having the same shape as the flat rectangular frame 22.
It is desirable to form them at 0 (see FIG. 5).

The reason is as follows.

In the present embodiment, the medium in the polishing tank 14 is vigorously stirred, and a large amount of bubbles float. Suspended matter is mainly abrasion fine powder of a binding resin (for example, polyester resin) of a resin medium, to which fine aluminum powder and inorganic grinding particles adhere. These are removed by overflow.

A specific procedure will be described below with reference to the overflow port 28.

Bubbles generated and floated during polishing are partially discharged from 28 during polishing (usually 5 minutes each for rotating the workpiece clockwise and counterclockwise), and the remaining remains in the upper portion of the polishing tank 14. When the polishing is completed, the polishing tank 14 is lowered, the work 16 is positioned above the upper surface of the polishing tank 14, and the work 16 is fixed to the jig (the mounting flange 72).
Remove from At this time, an operator cleans the work 16 with cleaning water using a spray gun or the like. The water level in the polishing tank 14 rises by the amount used as the washing water.

Next, when a new work 16 is mounted, the polishing tank 14 is raised, and polishing is started (rotating the work) in a state where the work 16 is submerged in the supernatant layer 84 of the liquid storage section 86, the water level rises. Then, a part of the foam remaining in the upper part of the polishing tank 14 is discharged from the overflow port 28. This operation is repeated, and when the liquid in the tank becomes more turbid, the amount of the suction water (suction water) is increased, and the amount of circulation is increased.

The overflow port 28 is connected to a wastewater treatment device (not shown) by a bellows hose 32. Further, in the illustrated example, on the drainage cover body 30, a pedestal receiving portion 36 of a temporary pedestal (wood or the like) 34 of the work 16 is formed on both sides in the longitudinal direction. This is for facilitating attachment / detachment of a large / heavy work.

The size of the polishing tank 14 is, for example, that the work is made of an aluminum wheel (having a diameter of 350 to 550 mm and a thickness of 1 mm).
50-300 mm), width: 800, length: 155
0, height 800 mm. The caliber hose 32 has a nominal diameter of 200 mm.

The elevating device 24 comprises an elevating plate 38 for fixing the polishing tank 14 and a ram 40 for driving the elevating plate 38 in the vertical direction. However, the present invention is not limited to this configuration. The device can be used.

The work rotating device 18 has a pair of work rotating shafts (thrust shafts) 42, a pair of thrust bearings 44, 44 for supporting these work rotating shafts 42, and a rotational drive for rotating the work rotating shaft 42 in the forward and reverse directions. Means 46.
The rotation driving means 46 includes a prime mover (motor: electric motor) 48.
And a transmission 50 arranged between the output shaft of the motor 48 and the upper end of the work rotating shaft 42. The transmission 50
In the illustrated example, the original vehicle (drive pulley) 52 on the motor side and the first and second driven vehicles (driven pulleys) 54, 5
4 is a belt transmission device in which a flat belt 56 is wound around an isosceles triangle with the original vehicle (drive pulley) 52 at the top.

The thrust bearing 44 is supported via a pair of brackets 62 fixed to the front surface of a beam 60a of a columnar support 60 formed on a base 58 of the polishing apparatus. The motor 48 has a motor support 64 formed on a bracket 63 fixed to the rear surface of the beam 60a.
Attached through. Rectangular motor support 64
The motor 48 can be adjusted and moved in the front-rear direction by screws 65, 65, and the tension of the flat belt 56 can be adjusted.

It should be noted that the belt transmission is desirable because the pulley idles when an impact load or an overload acts on the rotating shaft, so that the overload hardly acts on the motor and / or the rotating shaft. Gears, chains, rollers, etc.).

A work attachment / detachment device 68 is formed at the tip of the work rotation shaft 42. The work attaching / detaching device 68
Is not particularly limited as long as the work 16 can be easily attached and detached and there is no possibility that the work 16 will be detached during the high-speed rotation of the work. In the illustrated example (particularly, see FIG. 6), a mounting flange 72 corresponding to the adapter 70 screwed to the upper surface of the work 16 is formed at the tip of the work rotating shaft 42. The mounting flange 72 has a plurality of daruma holes 74 formed therein. A plurality of fixing bolts 76 are temporarily screwed to the adapter 70 in advance corresponding to the daruma holes 74. Then, the head 76a of the fixing bolt 76 is connected to the
4, the work 16 can be fixed to the tip of the work rotation shaft 42 by screwing the stop bolt 76 in a state where the work is rotated and the stop bolt is positioned on the small diameter side of the damper hole 74 after the work is rotated. Have been.

Further, in this embodiment, the work rotating shaft 4
2 is a plate-shaped baffle body 80 capable of forming an annular or cylindrical (annular in the illustrated example) media discharge gap 78 between itself and the upper edge.
It has. Here, the diameter of the plate-shaped baffle body 80 may be any size as long as the medium can be prevented from jumping out onto the liquid surface of the liquid storage part of the polishing tank. Normally, the diameter of the work 16 is set at 0.
9 to 1.5 times, preferably 1.0 to 1.2 times.
If the diameter is too small, it is difficult to prevent the medium from popping out. If the diameter is too large, the passage of the floating medium is reduced, and the polishing force of the design window is weakened.

The distance of the plate-shaped baffle body 80 from the front surface (design surface) of the work 16 is not particularly limited as long as the upward eddy flow can be smoothly generated on the medium. For example,
When the work 16 has the above size, the size is usually 8 to 15 cm. If the distance is too short, a smooth upward flow is unlikely to occur, and there is a possibility that the power required for the media to exhibit the design surface polishing action may increase. The plate-like baffle body 42
Is fixedly mounted on the work rotating shaft 42 in the illustrated example, but may be mounted so that it can be adjusted and moved in the vertical direction, and further, can be freely moved as described later. Further, a method may be adopted in which a bearing portion or a loose fitting hole of the rotating shaft is provided in the plate-shaped baffle body, and the plate-shaped baffle body is fixed to the polishing tank via a support racket or the like.

Although the upper limit of the distance between the work front surface 16a and the plate-shaped baffle body 80 is not particularly limited, the shorter the distance, the smaller the diameter of the plate-shaped baffle body is from the viewpoint of the medium jumping out. Also, the effect of preventing the media from jumping out can be easily achieved.

The role of the plate-like baffle 80 is to prevent scattering of the medium and to change the rising speed of the water (liquid) and the medium 82. For example, the plate-shaped baffle body 80 and the work 1
6 Make the gap with the top surface an appropriate distance (80-120mm)
When the rotational speed of the workpiece is set to about 400 rpm, it has been confirmed that the medium 82 is lifted with the upward flow of the liquid, collides violently with the baffle body 80, and is discharged from the gap to all directions. Therefore, the baffle body 80 is easily worn by the medium 82, and it is preferable to use a thick iron plate or a steel plate coated with urethane or abrasion-resistant rubber.

As a result of an experiment, the gap is desirably 80 to 120 mm. When the gap is widened, the amount of water passing through the gap increases, that is, the flow velocity becomes slow, the speed of the media (the relative speed at which the media moves in contact with the work) decreases, and the polishing force decreases.

On the other hand, if the gap is too small, the amount of media that should pass through smoothly is reduced, or the density of the media is increased, and the media collide with each other and the speed is reduced, so that the polishing force is also weak. The flow velocity (polishing force) of the medium is determined by the rotation speed of the work, the gap between the baffle and the work, and the distance between the design surface and the upper surface of the medium (settling layer).

When the plate-shaped baffle body 80 is of a fixed type, the size and mounting position of the plate-shaped baffle body 80 can be adjusted according to the diameter of the work 16 and the type of the medium 82 so that the plate baffle body 80 can be adjusted. It is desirable to be adjustable.

Further, even if the plate-like baffle body 80 is mounted to be freely movable up and down with respect to the rotation axis of the work, the effect of preventing the medium from jumping out is achieved. In this case, the plate-like baffle body 80
Is desirably molded from plastic having a specific gravity of 1.0 to 1.2, which can be almost freely moved in water, so that the flow of the medium is not hindered. In this case, the gap between the plate-shaped baffle members at the upper end of the work increases according to the flow speed of the media, and smoother media flow can be expected. Although not shown, the work rotating shaft 42 in this case may be provided with a stopper at a substantially liquid level position of the liquid storage portion for describing a further rise of the plate-shaped baffle body 80. Prevention can be guaranteed.

The plane shape of the plate-like baffle body 80 is as follows.
Usually, the shape is circular, but if it has a flat portion capable of preventing the media from popping out, it may be triangular, quadrangular, polygonal, or even a windmill shape in which the outer peripheral side is cut out at a predetermined pitch. In such a case, it can be expected that the media flow generated by the rotation of the work is further promoted.

The above-mentioned polishing apparatus is usually provided with a control panel (P
Through the LC), the ON / OFF and work rotating device 18 and the elevating device 24 are linked in accordance with a program as appropriate.

Next, a method (one embodiment) of the present invention using the above polishing apparatus will be described.

In the method of the present invention, a workpiece (polished object) 16 having at least one surface to be polished 16a and a through-hole 16b around the center of the polished surface is formed by using a granular medium 82. This is a method of polishing (grinding). An aluminum wheel is taken as an example of the work 16 (see FIGS. 4 and 6).

In the aluminum wheel 16, the polished surface 16a is a design surface (front surface). And the design surface 16
An axle mounting hole 16c is formed in the center of a, and a plurality of design windows 16b as through holes are formed around the mounting hole 16c.

The design window 16b can be 3 to 3 depending on the design.
There are 20 different shapes and sizes. In order to polish the interior of the design window 16b, that is, the concave portion (to allow the media to pass smoothly), when the number of windows is small, the work can be polished with a large number of work revolutions. If it is not lowered, it cannot be polished (the media is hard to get inside). If only the design surface is separate from the recess, increasing the number of revolutions will increase the polishing power.

The form of the above-mentioned granular media has the following desirable forms depending on the purpose of polishing, but is not particularly limited, and is usually a disk, a diamond, a triangle, a cone, a pyramid, a double pyramid (dipyramid) cylinder. , Prisms, spheres, hemispheres, shells and the like can be used arbitrarily, and can be used alone or in combination.

The larger the size of the medium, the stronger the abrasive power. However, corners and complicated shapes cannot be hit without entering in large-sized media. For this reason, at the start, for example, 20 mm, 15 m
Start by mixing m, 10mm sizes in a ratio of 5: 3: 2. As the media wears out and becomes smaller, the size to be replenished is only 20 mm.

In order to smooth the surface (for heavy cutting) as a pretreatment for gloss plating (usually gloss chrome plating) or gloss buffing, a resin medium is usually used. Here, the resin medium refers to a medium in which abrasive grains (alumina, silica, silicon carbide, etc.) are bonded with a resin (polyester, epoxy resin, etc.). The shape of the resin medium is conical, pyramidal, triangular prism, hemispherical, or the like, and has a size of 5 to 20 mm, preferably about 10 to 15 mm.

In order to make the aluminum wheel have a semi-glossy finish, a ceramic medium having a small diameter is used after the above-mentioned smoothing polishing. The form of the ceramic media is triangular prism, spherical, etc., 0.5 to 4 mm, preferably 1 to 4 mm.
The size is about 2 mm.

Next, a description will be given of a method of polishing the workpiece using the granular media.

In this case, a plurality (2
Are polished simultaneously, but the same is true for a single workpiece.

Simultaneous polishing of a plurality of works not only reduces equipment costs for producing a fixed amount but also produces the following effects.

A part of the medium 82 lifted in a tornado shape collides with the design surface 16a of the work 16, and the design surface 16a
Scattered in all directions while grinding. The remaining media passes through the design window, collides with the plate-like baffle body 80, and
Jump out from the plate-shaped baffle body gap in all directions. When a plurality of workpieces are arranged at an appropriate distance and rotated, the scattered media collide with each other, causing a complicated movement, and is particularly effective in uniformly polishing the design surface.

When only one workpiece is polished, the media immediately below the workpiece (the upper part of the sedimentary layer) always exhibits a mountain shape as a result of the media being lifted in a tornado shape. However, when two workpieces are attached, the shape of the mountain changes during polishing. It is considered that slight changes in water flow due to collision between media are amplified. This tendency becomes more severe when two work pieces having different mounting positions or designs are mounted.

Further, as a result of the experiment, it has been confirmed that the polishing force is increased by 20 to 30%.

First, a liquid storage section 86 composed of a settling layer 83 composed of a particle medium (polishing medium) and a supernatant layer 84 is formed in the polishing layer 14.

At this time, the respective heights of the sedimentation layer 83 and the supernatant layer 84 are such that the surface 16 to be polished (design surface) of the work 16 is placed on the supernatant layer 84.
6a is immersed in the work 16 so as to face the sedimentation layer 83,
When the work 16 is rotated, there is no particular limitation as long as a floating flow (upflow; tornado shape) toward the surface to be polished can be generated. That is, the height of the settling layer 83 is
It is assumed that the amount of the medium is such that the medium can be suspended and flowed at a speed at which the medium can be polished during the rotation of 6, and without generating an overload on the power source (motor).

The amount of the medium is not particularly limited, but is usually 50 to 200 mm, preferably 100 to 150 mm, with the sedimentation layer being substantially flat. If it is less than 50 mm, the media is drawn directly below the work in accordance with the rotation of the work, and the media at the four corners of the polishing layer are lost, and the ascending media is reduced and the polishing force is reduced. If the amount is too large, the amount of the supernatant layer will be reduced by that amount, and the water surface will be vigorously stirred, causing water to scatter.

The height of the supernatant layer 84 is such that the work 16 can be completely immersed, and the medium can be polished when the work is rotated, as described above.
The amount of liquid (amount of water) that can be caused to float and flow without generating an overload on the surface.

Specifically, the aluminum wheel (work) 1
The size of 6 is 500mm in diameter x 250mm in height x wall thickness of general part 3
In the case where a surface smoothing treatment before gloss plating is used using a resin medium having a 20 mm frusto-conical cone shape, the following configuration is adopted.

The size of the polishing tank 14 is set to 800 mm
× length 1550mm × height 800mm, liquid storage part:
750-850 mm, sedimentation layer 83: 100-150 mm, and supernatant layer 84: 650-700 mm.

If the height of the supernatant layer 84 is too small,
When the work 16 is immersed and rotated at a high speed, the water and the medium violently jump from the water surface and jump out of the polishing tank,
It is no longer an environment where polishing is possible.

When the work is not a cylindrical body such as an aluminum hole, for example, a screw 16 as shown in FIG.
In the case where A is polished, a cylindrical baffle (liquid flow guide cylinder) 81 is arranged at a peripheral position above the surface to be polished, and the cylindrical baffle is formed through a through space of the object 16A to be polished. It is desirable to generate a floating flow toward the inside.

A similar effect can be expected by reducing the height of the sedimentation layer 83 and slightly reducing the diameter of the polishing tank. The circulating properties of the media decrease, and the polishing ability relatively decreases.

Normally, above the cylindrical baffle body (peripheral wall body in the case of an aluminum hole) 81, the upper end edge of the cylindrical baffle body (peripheral wall body in the case of an aluminum hole) 13 when the work 16 rotates. A plate-like baffle body (baffle plate member) 80 capable of forming a media discharge gap therebetween is provided. The main function of the plate-shaped baffle body 80 is to prevent the medium from jumping out of the polishing tank and to increase the polishing force of the medium (adjust the rising speed of the medium) as described above.

For this reason, it is desirable that the diameter of the plate-shaped baffle body 52 be substantially the same as or slightly larger than the diameter of the cylindrical baffle body 13. The height of the discharge gap (cylindrical space) 54 forming the gap is 50 to 200 mm in the above example, preferably 80 to 1 mm.
20 mm.

If the gap is too small, the flow resistance of the medium increases, and the medium circulation property decreases. If the gap is too large, the media will spread and the media circulation will also decrease.

Next, as described above, after the liquid reservoir 86 is formed, the aluminum wheel (work) 16 which is a work is attached to the tip of the work rotating shaft 42, and the front surface (the surface to be polished) The work is immersed with the surface 16a facing the settling layer 83. The gap at this time is about 80-150mm
And At the time of immersion, the work rotating shaft 42 may be lowered, but usually, the polishing tank 14 is connected to the lifting device (jack) 2.
Perform by raising it with 4.

A description will be given based on FIG. (The numbers with circles correspond to those in the figure, respectively.) First, when the rotation is started at the initial rotation speed (for example, 100 rpm), the medium does not move.

When a few seconds have elapsed after the start of rotation, the medium 82 is lifted up a little, and flows sideways on the work design surface 16a.

When the rotation speed is gradually increased from the initial rotation speed (for example, 200 rpm), a part of the medium 82 hits the design surface 16a and flows sideways, and a part of the medium 82 moves upward from the design window 16b. Float. At this point, the rising speed of the medium is
Impact energy given to the design surface by the
The polishing power of No. 2 is weak.

When the rotation speed is further increased to a steady rotation speed (for example, 350 to 450 rpm), a part of the medium 82 hits the design surface 16a and flows sideways, and a part of the medium 82 extends from the design window 16b to the upper side of the work 16 as described above. Rise to At this point, since the rising speed of the medium 82 is high, the collision energy applied to the design surface 16a by the medium 82 is large, and the polishing force of the medium 82 is increased.
Then, as shown in the figure, when the plate-shaped baffle body 80 does not exist, the medium 82 jumps over the liquid surface of the liquid storage unit 86 and scatters outside the polishing tank 14.

In the above, in the present embodiment, since the plate-shaped baffle body 80 exists, the work 16 moves in the radial direction of the work 16 from the media discharge gap 78 formed by the work peripheral wall body 16d and the plate-shaped baffle body 80 and sinks. Collected and used efficiently.

If the plate-shaped baffle 80 does not exist, the polishing force is reduced for the above-mentioned reason.

The polishing time varies depending on the state of the design surface of the work. However, when polishing is performed directly from the casting surface, the polishing time is about 5 to 15 minutes each in the forward and reverse directions.
Minutes.

Also, there is a case where the medium is not sufficiently inserted into the center portion of the workpiece or a portion of a complicated design, and it is difficult to polish the medium. In this case, if the polishing of the present invention is performed after local buffing, air blasting, etc., are performed in advance, a uniform finish can be obtained.

When the media does not enter the center directly, it is mainly the case that the shape of the design window is narrow, such as a slit shape. It is possible to cope with cases where the media does not enter the design part enough and it is difficult to polish.

During polishing, the medium is consumed and the inside of the polishing tank gradually becomes dirty. Therefore, a certain amount of supernatant layer is continuously or each time withdrawn from the polishing tank 14 (for example, overflowed), and filtered through a filter press or a filter to remove sludge and remove filtered water. By returning to the polishing tank, the liquid in the polishing tank can be kept constant.

At this time, if a very small amount of a coagulant, for example, a surfactant (main component: benzalkonium chloride, hexylene glycol) or polyaluminum chloride is added to the supernatant layer 84, the filterability is improved. It is possible to prevent clogging of the filter and the like.

When the polishing is completed, the work tank 16 is pulled up from the liquid storage unit 86 by lowering the polishing tank 14 by operating the elevating device 24. In this state, before removing the work 16, the attached dirt is washed away with a spray gun using washing water (it is necessary to wash the surface 16 for a while before the surface dries). Then, if the work 16 is removed from the work rotating shaft 42 by loosening the fixing bolt 65 in the work attaching / detaching device 68, the polishing operation is completed.

[0090]

According to the polishing method of the present invention, as described above, a liquid storage section composed of a settling layer composed of granular media (polishing medium) and a supernatant layer is formed in a polishing tank, and After the work is immersed with the surface to be polished facing the sedimentation layer, the work is rotated to generate a floating flow toward the surface to be polished in the granular media, thereby polishing (grinding) the surface to be polished. The following effects are obtained by the configuration to be performed.

The polishing power and the polishing uniformity are greatly improved. Then, only the required surface can be selectively polished, and as a result, the polishing energy consumption can be reduced. Further, the initial power load when the workpiece is brought into contact (penetration) with the granular medium is small. This is because the ratio of the medium to the liquid to be used is much smaller than that of the conventional polishing method.

That is, from the viewpoint of running cost, the conventional method (rotary barrel, vibrating barrel, fluid barrel, centrifugal barrel, etc.) of the barrel polishing method requires that the media be rubbed and consumed so that the work is consumed. Much more than wasted by grinding. However, it can be said that the method is polished efficiently because the ratio of media to liquid is small.

The same applies to the case where the medium is moved using vibration even in the spin finish. (In addition, when the work is rotated in the bath without applying vibration, not only does power consumption increase, but also the rotation of the work causes the medium to rotate. In a dry barrel (media such as walnuts), the fine aluminum powder of the shaved workpiece adheres to the media surface. If the media is repeatedly polished, the media surface becomes silver with fine aluminum powder (media Surface clogging) Abrasive power is greatly reduced. In that case, it is necessary to discard the media or wash and dry it and then coat the abrasive and wax again.

One of the features of the present invention is that the media passes through the interior of the design window together with the upward flow and violently hits the plate-shaped baffle body, so that the recesses, holes and the inner peripheral surface can be polished. It is in. Usually, there is no supernatant layer in spin finish and there is no upward flow of the media. Therefore, the abrasive power of the design window is extremely weak.

An apparatus having a configuration similar to that used in the polishing method of the present invention is disclosed in US Pat. No. 5,857,901.

The polishing apparatus comprises a polishing tank capable of storing a polishing medium / water mixture therein, a rotating shaft capable of fixing a workpiece, and a concentric plate fixed to a main shaft in the polishing tank. Having the basic configuration.

However, the manner of use is completely different. That is, when the work (wheel 18) is immersed (submerged) in the liquid storage section, the liquid storage section is not separated into a sedimentation layer (media layer) and a supernatant layer (water layer). body
(water and media mixture 59). For this reason, when the work is immersed, the media is present in the room (chamber 68) formed from the work and the plate from the beginning, and when the work is rotated at high speed, the medium is formed by the gap between the periphery of the upper end of the work and the plate. Cylindrical flow channel
It is released outside the work (outside the work) by centrifugal force via (69). As a result, the inside of the work is reduced in pressure, and the water / media mixture is drawn into the work from directly below the work through a hole (design window) in the front surface (design surface 16a) of the wheel center. In this way, the water / media mixture is drawn into the front surface (design surface) of the wheel, and the media is polished by colliding with and rubbing against the front surface (design surface) of the wheel. (See U.S. Pat. No. 6, column 22-48).

That is, in the polishing method of the present invention, the media initially exists as a sedimentary layer below the work and contacts the work for the first time due to the rotation of the work, whereas the method described in US Pat. From the beginning, the media is in contact with the workpiece as a water / media mixture.

[0099]

EXAMPLE An aluminum wheel was polished under the following conditions.

Setting condition of polishing tank Work outer diameter 432 mm Settling layer (media) height 150 mm Settling layer and work design surface distance 100 mm Between plate-shaped baffle and work 80 mm Rotation speed 400 rpm Polishing time Casting forward and reverse 10 minutes Rough buff Product 〃 Each 5 minutes After the process, hard chrome plating was performed after the sisal buff.

In each case, beautiful glossy finished products were obtained.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing an example of a polishing apparatus used in the present invention.

FIG. 2 is a schematic front view of the same.

FIG. 3 is a schematic side view of the same.

FIG. 4 is a front sectional view of the same use mode.

FIG. 5 is a partial perspective view showing the overflow section.

FIG. 6 is a perspective view showing an attachment mode of an aluminum wheel (work).

FIG. 7 is a schematic explanatory view of the operation at each stage when the polishing method of the present invention is applied to an aluminum wheel.

FIG. 8 is a schematic operation explanatory diagram when the polishing method of the present invention is applied to a screw.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Polishing apparatus 14 Polishing tank 16 Aluminum wheel (work) 16a Design surface (surface to be polished) 16b Design window (through space) 42 Work rotation axis 68 Work attaching / detaching device 80 Plate baffle body 81 Cylindrical baffle body 82 Granular media 83 Sedimentation Layer 84 Supernatant layer 86 Reservoir

Continued on the front page (72) Inventor Masao Hirano 51, Shinmei Ufuji, Nishiharumachi, Nishikasugai-gun, Aichi Prefecture F term (in reference) 3C058 AA02 AB01 AB06 AC04 CB03

Claims (9)

[Claims] 1. At least one surface to be polished (ground surface)
In a method of polishing (grinding) a work (a material to be polished) having a through-hole around the center of the surface to be polished using a granular medium, the method comprises the steps of: After forming a liquid storage part comprising a sedimentation layer and a supernatant layer, the work is immersed in the supernatant layer with the polished surface facing the sedimentation layer. A polishing method using granular media, wherein a floating flow toward the surface to be polished is generated in the medium to polish (grind) the surface to be polished. 2. A cylindrical baffle (liquid flow guide cylinder) is disposed at a position above the surface to be polished and is provided inside the cylindrical baffle via a through-hole of the object to be ground. 2. The polishing method according to claim 1, wherein the surface to be polished is polished by generating a floating flow. 3. A plate-shaped baffle member (baffle plate member) capable of forming a media discharge gap with an upper edge of the cylindrical baffle member when rotating the work. A polishing method using the granular media described. 4. The polishing method according to claim 3, wherein the plate-shaped baffle body is fixed to a work rotating shaft for holding and rotating the work. 5. The work is an automobile wheel,
5. The polishing method according to claim 1, wherein the peripheral wall portion of the wheel body also serves as the baffle body. 6. A polishing apparatus used for polishing (grinding) a workpiece having at least one surface to be polished and having a through-hole around a central portion of the polished surface, wherein the sedimentation made of granular media is performed. A polishing tank capable of forming a liquid storage section composed of a layer and a supernatant layer, a rotating shaft that holds the work at the tip and rotates in the supernatant tank, and a rotation drive unit that rotates the rotating shaft; A polishing apparatus using granular media, comprising: 7. The polishing apparatus according to claim 6, further comprising a cylindrical baffle at a position above the surface to be polished. 8. The apparatus according to claim 7, further comprising a plate-shaped baffle body capable of forming a medium discharge gap between the cylindrical baffle body and an upper end edge of the cylindrical baffle body. Polishing equipment using granular media. 9. Polishing by granular media according to claim 6, wherein a part of a peripheral wall of an upper end of the polishing tank is cut out to provide a means for overflowing a stored liquid. apparatus.