Grinding device and method for manufacturing metal product

Abstract

Provided are: a grinding device capable of achieving excellent grinding life; and a method for manufacturing a metal product. This grinding device includes: a grinding member having a plurality of grinding surfaces that are concentrically arranged in a radial direction around a rotation axis and have different angles with respect to a reference plane perpendicular to the rotation axis; and an operation unit that grinds a material to be ground with one of the plurality of grinding surfaces by moving relative to the material to be ground in a direction intersecting the rotation axis while holding and rotating the grinding member around the rotation axis. The operation unit can change a grinding usage surface used for grinding among the plurality of grinding surfaces by changing the orientation of the rotation axis of the grinding member with respect to the material to be ground.

Description

Grinding apparatus and method for manufacturing metal products

[0001] This invention relates to a grinding apparatus and a method for manufacturing metal products.

[0002] A grinding device is known that includes a grinding member having a grinding surface, and an operating unit that holds the grinding member and rotates it around a rotation axis, while moving it in a direction perpendicular to the rotation axis relative to the material to be ground, thereby grinding the material to be ground with the grinding surface (see, for example, Patent Document 1).

[0003] Japanese Patent Publication No. 2018-20393

[0004] The present invention aims to provide a grinding apparatus and a method for manufacturing metal products that can achieve excellent grinding life.

[0005] One embodiment of the present invention is as follows:

[0006] [1] A grinding device comprising: a grinding member having a plurality of grinding surfaces arranged radially in concentric circles around a rotation axis and having different angles with respect to a reference plane perpendicular to the rotation axis; and an operating unit that holds the grinding member and rotates it around the rotation axis, while moving it in a direction perpendicular to the rotation axis relative to the material to be ground, thereby grinding the material to be ground with one of the plurality of grinding surfaces, wherein the operating unit can change the orientation of the rotation axis of the grinding member relative to the material to be ground, thereby changing the grinding surface used for grinding among the plurality of grinding surfaces.

[0007] [2] The grinding apparatus according to [1] wherein the plurality of grinding surfaces have an angle with respect to the reference surface that increases radially outward between radially adjacent grinding surfaces.

[0008] [3] The grinding apparatus according to [1] or [2], wherein each of the plurality of grinding surfaces has an angle with respect to the reference surface that is greater than 0° and less than 90°.

[0009] [4] The grinding apparatus according to any one of [1] to [3], wherein the grinding member comprises a grinding support member and an elastic grinding wheel, the grinding support member has a plurality of grinding support surfaces arranged concentrically in the radial direction with respect to the rotation axis and having different angles with respect to the reference surface, and the elastic grinding wheel has a circular shape with respect to the rotation axis and forms the grinding surface when sandwiched between one of the plurality of grinding support surfaces and the material to be abraded.

[0010] [5] A grinding apparatus according to any one of items [1] to [4], wherein, when viewed along the axis of rotation, the sum of the areas of the plurality of grinding surfaces accounts for 80% or more of the area of ​​the grinding member.

[0011] [6] The grinding apparatus according to any one of [1] to [5], wherein the operating unit comprises a rotary drive device that holds and rotates the grinding member, and a robot arm that changes the orientation of the rotary drive device with respect to the material to be ground.

[0012] [7] A grinding apparatus according to any one of [1] to [6], comprising a control unit that changes either or both the rotational speed of the grinding member and the pressing force of the grinding member against the material to be ground, in accordance with a change in the grinding surface.

[0013] [8] A grinding apparatus according to any one of [1] to [7], comprising a control unit that controls the operating unit to change the grinding surface.

[0014] [9] The grinding apparatus according to [8], wherein the control unit controls the operating unit to change the grinding surface when the grinding capacity of the grinding surface being used decreases.

[0015]

[10] The grinding apparatus according to [8] or [9], wherein the control unit changes the grinding surface based on the load when the grinding member is rotationally driven.

[0016]

[11] A method for manufacturing a metal product, comprising grinding the surface of a metal material to be ground using a grinding apparatus described in any one of items [1] to

[10] .

[0017] According to the present invention, it is possible to provide a grinding apparatus that can achieve excellent grinding life and a method for manufacturing metal products.

[0018] This is an external view showing a grinding device according to one embodiment of the present invention. (a) is a partial cross-sectional side view showing the grinding member shown in Figure 1, and (b) is a cross-sectional view taken along A-A in (a). (a) is a cross-sectional view showing the state during grinding with the grinding device shown in Figure 1, and (b) is a cross-sectional view showing the state when the grinding surface is changed from the state shown in (a). This is a graph showing the relationship between the distance from the rotation axis to the grinding surface and the grinding depth, as an example of the test results obtained in the embodiment. This is a graph showing the relationship between the cumulative number of rotations of the grinding wheel and the grinding depth, as an example of the test results obtained in the embodiment. This is a figure showing the relationship between the cumulative number of rotations of the grinding wheel and the grinding depth, as an example of the test results obtained in the embodiment. This is a figure showing the relationship between the cumulative number of rotations of the grinding wheel and the load current of the rotation drive device, as an example of the test results obtained in the embodiment.

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0020] As shown in Figures 1 to 3, in one embodiment of the present invention, the grinding apparatus 1 includes a grinding member 3 having a plurality of grinding surfaces 2 (three in this embodiment) arranged radially in concentric circles around a rotation axis O and having different angles with respect to a reference plane S perpendicular to the rotation axis O (see Figure 2(a)), and an operating unit 5 that holds the grinding member 3 and rotates it around the rotation axis O, moving it in a direction intersecting the rotation axis O relative to the material to be ground 4, thereby grinding the material to be ground 4 with one of the plurality of grinding surfaces 2. The operating unit 5 can change the direction of the rotation axis O of the grinding member 3 relative to the material to be ground 4, thereby changing the grinding surface used for grinding among the plurality of grinding surfaces 2 (see Figures 3(a) and (b)). With the above configuration, if the grinding capacity of the grinding surface being used decreases, the grinding surface can be changed, so grinding can be continued while maintaining the grinding capacity by changing the grinding surface. Therefore, an excellent grinding life can be achieved.

[0021] In this embodiment, for convenience, the direction along the rotation axis O is referred to as the vertical direction, the direction from the grinding member 3 toward the workpiece 4 along the axial direction is referred to as the downward direction, the opposite direction is referred to as the upward direction, the direction perpendicular to the rotation axis O is referred to as the radial direction, and the direction around the rotation axis O is referred to as the circumferential direction.

[0022] As shown in Fig. 2(a), among the plurality of grinding surfaces 2, the angle with respect to the reference surface S increases toward the radially outer side between the radially adjacent grinding surfaces 2. The plurality of grinding surfaces 2 have a first grinding surface 2a, a second grinding surface 2b, and a third grinding surface 2c in this order facing radially inward. Let the angle of the first grinding surface 2a with respect to the reference surface S be the first angle θ １ , the angle of the second grinding surface 2b with respect to the reference surface S be the second angle θ ２ , and the angle of the third grinding surface 2c with respect to the reference surface S be the third angle θ ３ . When this is done, θ １ > θ ２ > θ ３ . Each of the plurality of grinding surfaces 2 has an angle with respect to the reference surface S that exceeds 0° and is less than 90°. Note that the number of grinding surfaces 2 constituting the plurality of grinding surfaces 2 is not limited to three, and may be two or more. The number of grinding surfaces 2 and the area of each grinding surface 2 can be appropriately set according to the material of the workpiece 4 to be ground, the target grinding amount, and the like. From the viewpoint of making it difficult to cause point contact between the grinding use surface and the workpiece to be ground 4 at the start of grinding and making it easy to obtain a smooth grinding finish surface, the angle θ ３ with respect to the reference surface S preferably exceeds 0°, but is not limited to this, and the angle θ ３ may be configured to be 0°.

[0023] From the viewpoint of increasing the grinding life, it is preferable that the total area of the plurality of grinding surfaces 2 occupies 80% or more of the area of the grinding member 3 when viewed along the rotation axis O.

[0024] The grinding member 3 has a grinding support member 6 and an elastic grinding wheel 7. The grinding support member 6 has a plurality of grinding support surfaces 8 arranged radially in concentric circles centered on the rotation axis O and having different angles with respect to the reference surface S. The elastic grinding wheel 7 has a circular shape centered on the rotation axis O and forms a grinding use surface by being sandwiched between one of the plurality of grinding support surfaces 8 and the workpiece 4 to be ground.

[0025] The plurality of grinding support surfaces 8 have a first grinding support surface 8a, a second grinding support surface 8b, and a third grinding support surface 8c in this order facing radially inward. The angle of the first grinding support surface 8a with respect to the reference surface S is the first angle θ １It is identical to the second grinding support surface 8b with respect to the reference surface S, and the angle of the second angle θ ２ It is identical to the third grinding support surface 8c with respect to the reference surface S, and the angle of the third grinding support surface 8c with respect to the reference surface S is the third angle θ ３ It is identical to the above. The grinding support member 6 is a curved disc shape that gradually bends upward toward the radially outward direction. In addition, the thickness of the grinding support member 6 in the vertical direction decreases toward the radially outward direction, thereby avoiding interference with the member located above the grinding support member 6.

[0026] The elastic grinding wheel 7 has a disc-shaped elastic member centered on the rotation axis O, and a group of abrasive grains consisting of multiple abrasive grains embedded and held in the elastic member. The elastic member is formed from, for example, rubber or synthetic resin, and can bend upward along the multiple grinding support surfaces 8 by elastic deformation. Due to its flexibility, the elastic grinding wheel 7 can finish the surface of the workpiece 4 smoothly. To ensure flexibility, the thickness of the elastic grinding wheel 7 is preferably 2 to 3 mm. The grit size of the grinding wheel is not particularly limited, but from the viewpoint of removing scratches and obtaining a smooth finished surface, it is preferably #36 to #60.

[0027] The elastic grinding wheel 7 is not used alone, as it would deform excessively and break if pressed against the workpiece 4 under high-speed rotation. Instead, it is used with a grinding support member 6 positioned on the back (top) side. Preferably, the grinding support member 6 is flexible, allowing it to bend upward along the surface of the workpiece 4 by elastically deforming in response to the pressing force. In this case, the grinding support member 6 is made of, for example, synthetic resin (such as nylon). The flexibility of the grinding support member 6 increases the contact area between the elastic grinding wheel 7 positioned on the front side and the surface of the workpiece 4. The grinding support member 6 may also be configured without flexibility; in this case, it can be made of, for example, metal.

[0028] The grinding member 3 is not limited to a configuration having a grinding support member 6 and an elastic grinding wheel 7. For example, the grinding member 3 may be a detachable solid grinding wheel. However, if a solid grinding wheel is used continuously, the shape of the grinding wheel may change. In other words, the area of ​​the grinding surface and the adjacent grinding surface 2, as well as the position (height) of the grinding surface, will change, making control more complex. Therefore, it is preferable that the grinding member 3 has a configuration having a grinding support member 6 and an elastic grinding wheel 7.

[0029] The operating unit 5 includes a rotary drive device 5a that holds and rotates the grinding member 3, and a robot arm 5b that changes the orientation of the rotary drive device 5a relative to the material to be ground 4. Preferably, the grinding member 3 is detachable from the rotary drive device 5a.

[0030] The rotary drive device 5a rotates the grinding support member 6 and the elastic grinding wheel 7 together around the rotation axis O, as shown by the thick arrow in Figure 2. Alternatively, the rotary drive device 5a may be configured to rotate only the elastic grinding wheel 7. In this case, the upper surface of the elastic grinding wheel 7 will slide circumferentially against the lower surface of the grinding member 3 while the elastic grinding wheel 7 rotates. The rotary drive device 5a has an electric motor (not shown) as a rotation drive source. However, the rotary drive device 5a is not limited to this; for example, it may also have a hydraulic motor as a rotation drive source.

[0031] The robot arm 5b includes a support 5b1 that supports the rotary drive device 5a, an arm base 5b2 positioned above the support 5b1, and a load sensor 5b3 that detects the vertical load acting between the support 5b1 and the arm base 5b2 (the reaction force when the grinding surface is pressed against the material to be abraded 4). In this embodiment, the load sensor 5b3 is interposed between the arm base 5b2 and the support 5b1, but is not limited to this configuration.

[0032] The grinding device 1 has a control unit 9 constituted by a computer or the like that controls the operation of the operation unit 5. The control unit 9 is electrically connected to the rotary drive device 5a in an operable manner and controls the rotation of the grinding member 3. Further, the control unit 9 is electrically connected to the robot arm 5b in an operable manner and controls the orientation of the rotation axis O of the grinding member 3 with respect to the workpiece 4 by controlling the posture of the robot arm 5b. The control unit 9 controls the operation unit 5 to change the grinding use surface when the grinding ability of the grinding use surface during use decreases. When the grinding ability of the grinding use surface during use decreases, the load (current value or voltage value) of the rotary drive device 5a when rotating the grinding member 3 decreases. Therefore, it is preferable that the control unit 9 is configured to change the grinding use surface based on the load. In this case, for example, the grinding use surface can be changed when the load falls below a threshold value.

[0033] It is preferable to use the plurality of grinding surfaces 2 as the grinding use surfaces in the order of the first grinding surface 2a, the second grinding surface 2b, and the third grinding surface 2c. That is, it is preferable to use the plurality of grinding surfaces 2 starting from the grinding surface 2 on the outer side in the radial direction first. According to the above configuration, even if the grinding surface 2 on the outer side in the radial direction slides with respect to the workpiece 4 when grinding is performed using the grinding surface 2 on the inner side in the radial direction, the grinding surface 2 on the outer side in the radial direction can suppress the influence on the workpiece 4 because the grinding ability has decreased.

[0034] Further, the control unit 9 is operably connected to the load sensor 5b3 and, according to the detection result of the load sensor 5b3, the downward pressing force N of the grinding member 3 against the workpiece 4 by the robot arm 5b Ｒ is controlled. As shown by the white arrow in FIG. 3, the control unit 9 controls the robot arm 5b to move so that the grinding use surface moves downward along the surface of the workpiece 4. Note that the operation unit 5 may be configured to move the workpiece 4 instead of the robot arm 5b, or may be configured to move both.

[0035] Between two grinding surfaces 2 adjacent to each other in the radial direction, since the distance L from the rotation axis O to the grinding surface 2 (the center of the radial width thereof) is different, the circumferential length of the grinding surface 2 is different, so the grinding ability per rotation is different. Also, since the angle of the grinding surface 2 with respect to the reference surface S is different, the pressing force N applied downward to the grinding member 3 with respect to the workpiece 4 Ｒ is different even when the pressing force N acting perpendicular to the surface of the workpiece 4 is the same. Therefore, in order to suppress the change in the grinding conditions (grinding ability) with respect to the workpiece 4 when changing the grinding surface to be used, the control unit 9, in response to the change in the grinding surface to be used, controls the rotational speed of the grinding member 3 and the pressing force N applied downward to the grinding member 3 with respect to the workpiece 4 Ｒ is preferably changed by one or both (preferably both) of them.

[0036] The pressing force N acting perpendicular to the surface of the workpiece on the grinding surface to be used is the angle θ of the rotation axis with respect to the normal line P of the surface and the pressing force N applied downward (that is, in the direction along the rotation axis O) Ｒ is used to represent N = N Ｒ × cos θ. The control unit 9 controls the pressing force N acting perpendicular to the surface of the workpiece based on the angle θ appropriately detected by an angle sensor (not shown) and the pressing force N applied downward detected by the load sensor 5b3 Ｒ .

[0037] The grinding apparatus 1 is preferably used in a method for manufacturing a metal product that grinds the surface of a metal material as the workpiece 4 with the grinding member 3. The metal product manufactured by the grinding apparatus 1 has a smooth finish surface with surface defects such as dents and steps suppressed. Since the influence of fluctuations in the grinding conditions (grinding surface 2, rotational speed, pressing force, etc.) when changing the grinding surface 2 as in the present embodiment on a metal material such as a steel material is smaller than that on a thermoplastic or thermosetting synthetic resin, etc., it is particularly suitable for use of the grinding apparatus 1 of the present embodiment.

[0038] The shape of the workpiece 4 is not particularly limited and can be any shape such as a plate shape, a cylindrical shape, or a columnar shape. Also, the shape of the surface of the workpiece 4 is not limited and may be a flat surface or a curved surface. That is, the grinding apparatus 1 of the present embodiment can be applied to both the case of grinding a flat surface and the case of grinding a curved surface.

[0039] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and the embodiments described above can be modified in various ways without departing from the spirit of the present invention.

[0040] A test was conducted using the grinding apparatus 1 of the embodiment described above. Figure 4 is a graph showing the relationship between the distance L from the rotation axis to the grinding surface and the grinding depth at the initial stage of grinding, when the rotation speed and feed rate of the grinding member are kept constant, as an example of the test results. The peripheral speed changes with distance L, and the grinding capacity changes accordingly. It can be seen that, regardless of the grinding surface, it is preferable to adjust the rotation speed of the grinding member 3 in accordance with the change in the grinding surface in order to achieve a predetermined amount of grinding.

[0041] Figure 5 is a graph showing the relationship between the cumulative number of rotations of the grinding wheel and the grinding depth on different grinding surfaces, when the rotation speed and feed rate of the grinding member are kept constant, as an example of test results. It can be seen that when the distance L from the rotation axis O is small, the area of ​​the grinding wheel used per rotation becomes small, and the grinding wheel wears out more easily. For this reason, between two radially adjacent grinding surfaces 2, it is preferable that the radially inner grinding surface 2 is used for a shorter time as a grinding surface. Accordingly, the control unit 9 may be configured to change the grinding surface between two radially adjacent grinding surfaces 2 so that the radially inner grinding surface 2 is used for a shorter time as a grinding surface.

[0042] Figure 6 shows an example of test results, illustrating the relationship between the cumulative number of rotations of the grinding wheel and the grinding depth when the rotation speed and feed rate of the grinding member are kept constant. Figure 7 shows the relationship between the cumulative number of rotations of the grinding wheel and the load current of the rotation drive device 5a in this case. It can be seen that a decrease in load current correlates with a decrease in grinding depth (grinding capacity).

[0043] 1. Grinding device 2. Grinding surface 2a. First grinding surface 2b. Second grinding surface 2c. Third grinding surface 3. Grinding member 4. Material to be abraded 5. Operating unit 5a. Rotary drive device 5b. Robot arm 5b1. Support 5b2. Arm base 5b3. Load sensor 6. Grinding support member 7. Elastic grinding wheel 8. Grinding support surface 8a. First grinding support surface 8b. Second grinding support surface 8c. Third grinding support surface 9. Control unit L. Distance from rotation axis to grinding surface N Ｒ N: Pressing force along the axis of rotation; O: Pressing force acting perpendicular to the surface of the workpiece; P: Axis of rotation; S: Normal to the surface of the workpiece; θ: Reference plane; θ: Angle of the axis of rotation with respect to the normal to the surface of the workpiece. １ First angle θ ２ Second angle θ ３ Third angle

Claims

1. A grinding device comprising: a grinding member having a plurality of grinding surfaces arranged radially in concentric circles around a rotation axis and having different angles with respect to a reference plane perpendicular to the rotation axis; and an operating unit that holds the grinding member and rotates it around the rotation axis, while moving it in a direction perpendicular to the rotation axis relative to the material to be ground, thereby grinding the material to be ground with one of the plurality of grinding surfaces, wherein the operating unit can change the orientation of the rotation axis of the grinding member relative to the material to be ground, thereby changing the grinding surface used for grinding among the plurality of grinding surfaces.

2. The grinding apparatus according to claim 1, wherein the angle between radially adjacent grinding surfaces with respect to the reference surface increases radially outward.

3. The grinding apparatus according to claim 1 or 2, wherein each of the plurality of grinding surfaces has an angle with respect to the reference surface that is greater than 0° and less than 90°.

4. The grinding apparatus according to any one of claims 1 to 3, wherein the grinding member comprises a grinding support member and an elastic grinding wheel, the grinding support member has a plurality of grinding support surfaces arranged concentrically in the radial direction with respect to the rotation axis and having different angles with respect to the reference surface, and the elastic grinding wheel has a circular shape with respect to the rotation axis and forms the grinding surface by being sandwiched between one of the plurality of grinding support surfaces and the material to be abraded.

5. The grinding apparatus according to any one of claims 1 to 4, wherein, when viewed along the axis of rotation, the sum of the areas of the plurality of grinding surfaces accounts for 80% or more of the area of ​​the grinding member.

6. The grinding apparatus according to any one of claims 1 to 5, wherein the operating unit comprises a rotary drive device that holds and rotates the grinding member, and a robot arm that changes the orientation of the rotary drive device with respect to the material to be ground.

7. A grinding apparatus according to any one of claims 1 to 6, comprising a control unit that changes either or both the rotational speed of the grinding member and the pressing force of the grinding member against the material to be ground, in accordance with a change in the grinding surface.

8. A grinding apparatus according to any one of claims 1 to 7, comprising a control unit that controls the operating unit to change the grinding surface.

9. The grinding apparatus according to claim 8, wherein the control unit controls the operating unit to change the grinding surface when the grinding capacity of the grinding surface being used decreases.

10. The grinding apparatus according to claim 8 or 9, wherein the control unit changes the grinding surface based on the load when the grinding member is rotationally driven.

11. A method for manufacturing a metal product, comprising grinding the surface of a metal material to be ground using a grinding apparatus according to any one of claims 1 to 10.

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