JP4079370B2 - Barrel polishing method and barrel polishing apparatus - Google Patents

Description

  The present invention relates to a fluid-type barrel polishing method and barrel polishing apparatus for polishing a workpiece while centrifugally flowing a mass composed of a workpiece and a medium in a polishing tank.

  In fluid barrel polishing, a mass consisting of a workpiece, which is an object to be polished, and a media, which is an abrasive material, is put into a polishing tank, and the workpiece is polished while the mass is centrifugally fluidized by a rotating disk provided at the bottom of the polishing tank. One example is shown in Patent Document 1. In this fluid type barrel polishing method, as shown in FIG. 1, the mass moves horizontally along the rotating direction of the rotating disk, and the inner wall of the polishing tank is lifted by the centrifugal force, and in the central direction at the top. While the vertical swirl flow that flows downward is combined and flows in a toroidal shape, the workpiece and the media are rubbed against each other, and the surface of the workpiece is polished.

However, in the conventional fluid barrel polishing, the media gradually wears as the polishing progresses, and there is a problem that it is difficult to avoid a decrease in polishing ability due to a decrease in mass amount or a decrease in frictional force between the workpiece and the media. . These problems are particularly noticeable in dry fluid barrel polishing.
JP-A-8-11057

  The present invention provides a fluidized barrel polishing method and barrel polishing apparatus capable of solving the above-described conventional problems, eliminating a decrease in polishing ability due to progress of polishing, and greatly improving the polishing ability as compared with the conventional one. It is intended.

  As a result of intensive studies to solve the above problems, the present inventors have found that the inner wall of the polishing tank is contrary to the conventional common sense that the polishing ability of fluidized barrel polishing is reduced if the natural flow of the mass is hindered. It has been found that the polishing ability can be greatly increased by controlling the flow of the mass that rises by a suitable means. In addition, the change in the polishing ability of the fluidized barrel polishing apparatus is a change in the amount of work transmitted from the rotating disk to the mass, in other words, it appears as a change in the rotational resistance of the rotating disk. Can be grasped from. Therefore, it has been found that if the mass flow control is performed so as to keep the load of the drive motor of the rotating disk constant, the polishing ability that decreases with the progress of polishing can be maintained constant.

The barrel polishing method of the present invention made based on the above knowledge is a barrel polishing method in which polishing is performed while swirling the mass with a rotating disk provided at the bottom of the polishing tank. In addition, the flow of the mass in the polishing tank is controlled by adjusting the force that presses the upper end of the mass rising along the inner wall of the polishing tank , and polishing is performed while maintaining the load of the drive motor within the set range. It is characterized by doing. In this case, for example, the load current value of the drive motor is preferably used as the load of the drive motor.

Further, by intermittently controlling the flow of the mass in the polishing tank, it is possible to alternately repeat the polishing performed while controlling the flow of the mass and the free polishing without controlling the flow of the mass.

The barrel polishing apparatus of the present invention, means for setting the polishing bath workpiece and the media is turned, the turntable for turning flow mass provided at the bottom of the polishing vessel, the load of the rotating disk of the drive motor, grinding It consists of movable means that controls the load of the drive motor to be maintained within a set range by adjusting the force that moves up and down at the upper part of the tank and presses the upper end of the mass rising along the inner wall of the polishing tank. It is characterized by this.

According to the present invention, polishing is performed within a set range of the load by setting the load of the drive motor of the rotating disk in advance by the load current value and controlling the mass flow in the polishing tank. A decrease in the polishing ability accompanying the progress of polishing can be detected as a decrease in the load on the drive motor of the rotating disk, so when the load decreases, polishing is performed by adjusting the force that holds the upper end of the mass rising along the inner wall of the polishing tank. By controlling the flow of the mass in the tank and maintaining the load within the set range, barrel polishing can be performed while maintaining the polishing ability constant. Moreover, by controlling the flow of the mass in the polishing tank, the frictional force between the workpiece and the medium can be dramatically increased as compared with the prior art. Such an effect of the present invention is particularly remarkable in dry barrel polishing, but is also exhibited in wet barrel polishing.

(First embodiment: movable means and lifting mechanism)
FIG. 2 shows a first embodiment of the dry type of the present invention, wherein 1 is a polishing tank into which a mass M composed of a workpiece and a medium is charged, and 2 is a dish-like rotating disk provided at the bottom of the polishing tank. It is. The turntable 2 has a peripheral edge curved upward so that the mass M can easily flow upward. The part where the polishing tank 1 and the mass M of the turntable 2 are in contact with each other is lined with an abrasion-resistant urethane rubber or the like. Reference numeral 3 denotes movable means made of a flexible material such as rubber that closes the upper opening 13 of the polishing tank 1. In this embodiment, the movable means 3 has a lid plate shape, and its peripheral portion is fixed to the upper end of the polishing tank 1. As shown in FIG. 2, it is preferable that the peripheral portion of the movable means 3 is curved so as to be in contact with the inner wall of the polishing tank 1. The height of the polishing tank 1 is set to be lower than the maximum height when the mass M freely flows in a centrifugal manner so that the upper end of the mass M that is centrifugally flowed can be suppressed by the movable means 3.

  The turntable 2 is disposed slightly above the bottom plate 10 of the polishing tank 1 and is rotated via the speed reducer 5 by the drive motor 20 while being in sliding contact with the inner wall 12 of the polishing tank 1 leaving the sliding contact portion gap 4. The The rotational speed of the drive motor 20 is controlled by the control means 50.

  A small hole 6 is provided in the turntable 2, and a gap 14 is formed between the turntable 2 and the bottom plate 10 of the polishing tank 1. A dust collector (not shown) is connected to the dust collection pipe 11 provided at the lower part of the gap 14, and dust generated by polishing passes through the gap 14 via the small hole 6 and the sliding contact gap 4. More dust is collected via the dust collection tube 11.

  The load of the drive motor 20 of the turntable 2 is always detected by a load detection unit built in the control unit 50. Although it is practical to use the load current for detecting the load of the drive motor 20, it is not necessarily limited to this. For example, the load power may be detected. In the present invention, the load current value can be set in advance by the load setting means 70, and the flow of the mass M in the polishing tank 1 is controlled by various flow control means as described in detail below. Thus, the polishing is always performed within the set load range of the drive motor 20.

  An opening 8 is formed in the center of the movable means 3 for allowing the mass M to be filled in the polishing tank 1 so that the flow is not smooth, so that a part of the mass M is released to make the flow smooth. In this embodiment, the support member 31 is fixed across the opening 8. An elevating mechanism 60 for moving the movable means 3 up and down is disposed above the movable means 3. The elevating mechanism 60 is movable means through an arm 62 pivotally mounted on a support 61 and a working rod 63 attached to the tip of the arm 62 and projecting above the support member 31 of the movable means 3. 3 includes a drive unit 64 that moves up and down 3 and a control unit 65 that receives a signal from a load current value detection unit built in the speed control unit 50 and drives the drive unit 64. The drive unit 64 may employ an appropriate method such as a hydraulic cylinder type or a ball screw type. In this embodiment, the movable means 3 and its elevating mechanism 60 constitute mass flow control means in the polishing tank 1.

  When a mass M made of a workpiece and a medium is put into the polishing tank 1 and the rotating disk 2 is rotated by the drive motor 20, the mass M ascends the inner wall 12 of the polishing tank 1 by centrifugal force as described above. In the present invention, the raised mass M flows in a toroidal shape while the flow region is limited by the movable means 3 and the flow direction is changed to the center direction of the polishing tank 1. The conventional common sense is that if the natural flow of the mass is hindered, the polishing ability of the fluidized barrel polishing is lowered, but in the present invention, contrary to such common sense, the flow of the mass rising on the inner wall of the polishing tank By controlling this with an appropriate means, the frictional force between the workpiece and the medium is greatly increased, and the polishing ability is remarkably improved as compared with the prior art.

  Further, as described above, as the polishing progresses, the corner portion (convex portion) of the media wears and the work is also polished. Therefore, the frictional force between the two decreases, and the polishing ability gradually decreases. However, in this embodiment, the elevating mechanism 60, which is a mass flow control means, lowers the movable means 3 so that the load of the drive motor 20 is maintained in a range preset by the setting means 70.

  That is, since the load of the drive motor 20, for example, the load current value decreases as the polishing ability decreases, the control unit 65 of the elevating mechanism 60 receives the signal from the load detection means built in the control means 50. The operating rod 63 is lowered as shown in FIG. In this way, by bending the central part of the movable means 3 downward, the upper part of the mass M that is swirling and flowing is pressed down to reduce the flow region, and the pressure applied to the mass M is converted by converting the ascending force of the mass M into the applied pressure. Increase. As a result, the frictional force between the workpiece and the medium increases, and the polishing ability that has been lowered by the progress of polishing can be recovered. At the same time, the load of the drive motor 20 is recovered. When the load of the drive motor 20 reaches a preset upper limit due to the lowering of the operating rod 63, the control means 50 issues a signal to stop the lowering of the operating rod 63 to the control unit 65, so that the load of the drive motor 20 is optimized. It can be recovered to a proper value.

  As described above, in this embodiment, the height of the movable means 3 is optimally adjusted using the load of the drive motor 20 as a parameter, so that the friction force between the workpiece and the medium is always controlled within a certain range. Thus, barrel polishing can be continued without degrading the polishing ability even when polishing progresses.

  After the polishing is completed, the movable means 3 is lifted above the polishing tank 1 by the lifting mechanism 60, and then the arm 62 is rotated in the horizontal direction around the support column 61. Next, by rotating the polishing tank 1 so as to stand up and rotating the turntable 2 vertically or more, the polished mass M can be easily taken out from the polishing tank 1.

(Second embodiment: modification of movable means and elevating mechanism)
In the first embodiment described above, the periphery of the flexible movable means 3 is fixed to the upper end of the polishing tank 1, but the movable means 3 is a rigid body such as metal as shown in FIG. You may provide so that it can slide up and down in the polishing tank 1 by the raising / lowering mechanism 60 in conjunction with the load of the drive motor 20. In this case, the outer diameter of the movable means 3 is made slightly smaller than the inner diameter of the polishing tank 1. In the left half of FIG. 4, the free flow path of the mass M in the conventional case without the movable means 3 is indicated by a broken line. In the second embodiment as well, the reduced polishing force can be improved by suppressing the upper part of the mass M that swirls and flow with the movable means 3, as in the first embodiment.

(Third embodiment: movable means and its pressurizing mechanism)
FIG. 5 shows a third embodiment of the present invention. A movable means 3 having an opening cylinder 32 in the center is slidably provided in the polishing tank 1, and the opening cylinder is also provided on the upper lid 15 of the polishing tank 1. 32 is provided with an outer cylinder 16 that can be slidably fitted. An annular pressurizing chamber 17 is formed between the upper lid 15 and the movable means 3, and pressurized fluid such as compressed air is supplied from a pressurized fluid supply port 18 provided in the upper lid 15 to pressurize the movable means 3 downward. .

  In this embodiment, when the load of the drive motor 20 decreases, the pressure of the pressure fluid supplied from the pressure fluid supply port 18 is increased, and the movable means 3 is pressed downward like a piston to flow the mass M. To control. In this way, the friction force between the workpiece and the medium can be increased, and barrel polishing can always be performed within the set range of the load of the drive motor 20.

  As shown in FIG. 6, the movable means 3 that can be expanded and contracted made of an elastic material such as rubber is provided on the upper portion of the polishing tank 1, and the compression / decompression mechanism (not shown) is compressed through a pressure fluid supply port 18 provided in the upper lid 15. By supplying a pressure fluid such as air to the pressurizing chamber 17 on the upper side, the movable means 3 can be expanded and contracted like a balloon. With such a structure, the flow region of the mass M can be controlled, and barrel polishing can always be performed within the set range of the load of the drive motor 20.

( Fourth embodiment: intermittent control)
Further, the control means 50 allows the mass M to move in a restrained state when the flow direction is changed by the movable means 3 and the workpiece is polished in a restricted state, and the mass M is free flowing without the flow direction being changed by the movable means 3. The barrel polishing can also be efficiently performed by intermittently controlling the flow of the mass M, assuming that the unconstrained polishing time to be polished can be set ( FIGS. 9 and 9 of Example 3 described later) . 10 ).

  That is, in the method of this embodiment, when the time for constrained polishing of a workpiece reaches a predetermined time or when the load falls below a set lower limit value, the movable means 3 is raised to a height at which the mass M does not contact. Alternatively, the work is brought into an unconstrained state by reducing the number of rotations of the rotating disk 2 until the mass M remains in contact with the movable means 3 while the height of the movable means 3 remains unchanged. During constrained polishing, the mixing state of the media and the workpiece may be shifted, resulting in a decrease in polishing efficiency. However, by intermittently releasing the restraint and swirling and flowing the mass M in a free state, the work and the medium are mixed uniformly again, so that the polishing efficiency can be further improved.

(Example 1: Elevating and lowering movable means)
Using a barrel polishing apparatus equipped with a polishing tank 1 having an inner diameter of 440 mm shown in FIG. 4, a test piece (SS400, a cylinder having a diameter of 15 mm and a length of 20 mm) as a work of a triangular prism medium and 1) in the polishing tank 1 The mass M, which is a mixture of the above, was thrown into 95% of the internal volume of the polishing tank 1, and the mass M was restrained by the movable means 3 while changing the flow direction to perform barrel polishing. In polishing, the rotation speed of the turntable 2 is 350 min ⁻¹ , the upper limit of the load current value of the drive motor 20 is set to 5.2 A, and the lower limit value is set to 5.0 A so that the load current value is kept within this setting range. The height of the movable means 3 was controlled. FIG. 7 shows a change in the load current value with the lapse of the polishing time together with a comparative example in which the movable means 3 is kept constant. In other words, in Example 1, the current value was repeatedly increased to 5.2 A because the movable means 3 was lowered when the polishing resistance decreased and the current value decreased to 5.0 A. However, Comparative Example 1 Since the polishing was continued with the movable means 3 kept constant at the initial position, the current value gradually decreased.

The polishing amount per workpiece at this time was 115 mg / hr as shown as 1) in FIG . On the other hand, in the comparative example with the movable means 3 kept constant, the polishing amount per work was 13 mg / hr, and the difference in the polishing amount reached 8.8 times. Further, FIG. 8 also shows the case where another work is used. The white data shows data when polishing is performed while the movable means 3 is kept constant, and the hatched data shows data when polishing is performed by the method of the first embodiment. The materials and dimensions of other workpieces are as follows.
2): Stainless steel, 3mm diameter, 21mm long cylinder
3) Ring with steel, outer diameter 14mm, inner diameter 13mm, thickness 12mm
4): Spring steel, 54 mm long, 27 mm wide, 4.5 mm thick plate The ratio of the polishing amount per workpiece between the method of the present invention and the conventional method is 9.9 times in 2), and in 3) 14.3 times and 18.6 times in 4), and it was confirmed that the polishing ability was greatly increased by the method of the present invention in any work.

( Example 2 : intermittent control)
In this example, under the same polishing conditions as in Example 1, the upper limit value of the load current value was set to 5.2 A, the lower limit value was set to 5.0 A, and 10 minutes was set as one polishing cycle as shown in FIG. After polishing the mass M for 9 minutes and 45 seconds in a constrained state, barrel polishing was performed by repeatedly polishing in the unrestrained state for 15 seconds. As a result, it was possible to improve the efficiency of further polishing than in Example 1 described above in this second embodiment, as shown in FIG. 10. Also, by performing intermittent control in this way, the workpiece and media are mixed uniformly again during unconstrained polishing, so that polishing can be performed uniformly without forming dents or uneven wear on the surface of the workpiece. did it.

It is a perspective view which shows the mass flow in the conventional fluid type barrel polishing. It is a fragmentary sectional view showing the 1st embodiment of the present invention. It is a fragmentary sectional view which shows the state which lowered | hung the movable means in 1st Embodiment. It is a fragmentary sectional view showing the 2nd embodiment of the present invention. It is a fragmentary sectional view showing the 3rd embodiment of the present invention. It is a fragmentary sectional view showing the modification of the 3rd embodiment of the present invention. 6 is a graph showing a change in load current value in Example 1. 3 is a graph showing a workpiece polishing effect in Example 1. FIG. 6 is a graph showing a control state of a load current value in Example 2. 10 is a graph showing the workpiece polishing effect in Example 2.

Explanation of symbols

M Mass 1 Polishing tank 2 Turntable 3 Movable means 4 Sliding contact gap 5 Reduction gear 6 Small hole 8 Opening 10 Bottom plate 11 Dust collection pipe 12 Inner wall 14 Gap 15 Top lid 16 Outer cylinder 17 Pressurization chamber 18 Pressure gas supply port 19 Scale Reference Signs List 20 drive motor 21 level sensor 31 support member 32 open cylinder 50 control means 60 lifting mechanism 61 support 62 arm 63 actuating rod 64 drive part 65 control part 70 load setting means

Claims (4)

In the barrel polishing method in which polishing is performed while the mass is swirled and flowed by a rotating disk provided at the bottom of the polishing tank, the load of the driving motor of the rotating disk is set in advance, and the flow of the mass in the polishing tank is determined by A barrel polishing method characterized in that polishing is performed while controlling a force for pressing an upper end of a mass rising along an inner wall and maintaining a load of the drive motor within a set range.   The barrel polishing method according to claim 1, wherein a load current value is used as a load of the drive motor. The barrel polishing method according to claim 1, wherein the flow control of the mass in the polishing tank is intermittently performed. A polishing tank into which workpieces and media are put in, a rotating disk provided at the bottom of the polishing tank to rotate and flow the mass, a means for setting a load of a driving motor for the rotating disk, and a polishing tank that moves up and down at the upper part of the polishing tank A barrel polishing apparatus comprising: movable means for controlling the load of the drive motor so as to be maintained within a set range by adjusting a force that presses the upper end of the mass rising along the inner wall.

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