Grinding method, grinding device, and method for manufacturing metal product

Abstract

The present invention extends the lifetime of a grinding member when grinding the surface of a material to be ground. This grinding method for grinding a surface of a material to be ground by using a grinding member extending in a direction in which a rotation axis is inclined with respect to a surface of the material to be ground comprises: a pull-grinding step of grinding the surface of the material to be ground by moving the grinding member in a feeding direction in a state where a rear end side in the feeding direction of the grinding member is in contact with the surface of the material to be ground while rotating the grinding member; and a push-grinding step of grinding the surface of the material to be ground by moving the grinding member in the feeding direction in a state where a front end side in the feeding direction of the grinding member is in contact with the surface of the material to be ground while rotating the grinding member.

Description

Grinding method, grinding device, and method for manufacturing metal products

[0001] The present invention relates to a grinding method, a grinding device, and a method for manufacturing a metal product, and in particular to a grinding method, a grinding device, and a method for manufacturing a metal product using the grinding device, for grinding away defects present on the surface of a metal material to be ground, thereby obtaining a finished surface without steps.

[0002] Grinding work, which involves removing flaws from steel and other metal materials using grinding equipment such as grinders, is dangerous work that exposes workers to vibrations, noise, dust, etc., and it is difficult to secure the necessary personnel, so labor-saving and automation are desired.

[0003] As a technology for automating grinding work, for example, Patent Document 1 discloses a technology in which the surface shape and flaw positions of a three-dimensional steel material are recognized by a sensor, and the target location is automatically ground using a grinding member attached to an arm robot. Patent Document 1 shows that the steel material is ground using a grinding member whose rotation axis extends in a direction inclined relative to the surface of the steel material.

[0004] International Publication No. 2022 / 079974

[0005] In grinding using a grinding member whose rotation axis extends in a direction inclined relative to the surface of a metal material, such as the grinding method disclosed in Patent Document 1, a method for improving the life of the grinding member has been desired.

[0006] In view of the above circumstances, the present invention aims to provide a grinding method and a grinding device that can improve the life of a grinding member when grinding the surface of a workpiece, and a method for manufacturing a metal product using the grinding device.

[0007] The present invention has been made to solve the above problems, and the gist and configuration of the present invention are as follows.

[0008] 1. A grinding method for grinding the surface of a workpiece using a grinding member whose rotation axis extends in a direction inclined relative to the surface of the workpiece, comprising: a pull grinding process in which, while rotating the grinding member, a rear end side of the grinding member in a feed direction is brought into contact with the surface of the workpiece, and the grinding member is moved in the feed direction to grind the surface of the workpiece, and a push grinding process in which, while rotating the grinding member, a front end side of the grinding member in the feed direction is brought into contact with the surface of the workpiece, and the grinding member is moved in the feed direction to grind the surface of the workpiece.

[0009] 2. The average grinding depth d of the surface of the workpiece in the pull grinding process ｐｕｌｌ and the average grinding depth d of the surface of the workpiece in the push grinding process. ｐｕｓｈ can be obtained from |d ｐｕｌｌ -d ｐｕｓｈ | / d ｐｕｌｌ 2. The grinding method according to 1 above, wherein the value is 0.30 or less.

[0010] 3. The grinding method according to claim 1 or 2, wherein a feed direction in the pull grinding step is a first direction on the surface of the workpiece, a feed direction in the push grinding step is a second direction opposite to the first direction, and the method further comprises a return grinding step between the pull grinding step and the push grinding step, in which the pull grinding step and the push grinding step are switched while continuing to grind the surface of the workpiece.

[0011] 4. The grinding method according to 3 above, wherein the depth of a step occurring at the boundary between the ground surface ground in the return grinding step and the unground portion of the surface of the workpiece is 0.4 mm or less.

[0012] 5. The grinding method according to any one of 1 to 4, wherein the grinding trajectory is set so that the width of the overlapping portion between the grinding surface in the adjacent pull grinding process and the grinding surface in the adjacent push grinding process is 30% or more of the average of the grinding width in the pull grinding process and the grinding width in the push grinding process.

[0013] 6. A grinding device for grinding the surface of a workpiece, comprising: a grinding member whose rotation axis extends in a direction inclined with respect to the surface of the workpiece, moving means for moving the grinding member, rotating means for rotating the grinding member about the rotation axis, and control means for controlling the moving means and rotating means, wherein the control means is configured to perform pull grinding, which grinds the surface of the workpiece by moving the grinding member in the feed direction while rotating the grinding member and keeping the rear end side of the grinding member in contact with the surface of the workpiece in the feed direction, and push grinding, which grinds the surface of the workpiece by moving the grinding member in the feed direction while rotating the grinding member and keeping the front end side of the grinding member in contact with the surface of the workpiece in the feed direction.

[0014] 7. A method for manufacturing a metal product, comprising grinding a surface of a metal material as the workpiece using the grinding device according to 6 above.

[0015] According to the grinding method, grinding device, and method for manufacturing a metal product using the same of the present invention, it is possible to automate the grinding operation of the surface of the workpiece while improving the life of the grinding members.

[0016] 1 is a schematic diagram showing the overall configuration of a grinding device in one embodiment of the present invention. (a) is a schematic diagram showing the state of pull grinding, and (b) is a schematic diagram showing the state of push grinding. It is a graph showing the change in grinding depth with respect to the cumulative grinding area. It is a schematic diagram showing an example of a grinding method. It is an enlarged view of a turning part. It is a graph showing the change in step with respect to the feed speed of the grinding wheel. It is a graph showing the change in step with respect to the turning path length.

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the grinding method, grinding device, and method for manufacturing a metal product using the grinding device of the present invention will be described in detail with reference to the drawings.

[0018] [Workpiece] The present invention is for grinding the surface of a workpiece. Examples of the workpiece include metal materials. Any metal material can be used as the metal material. The material of the metal material is not limited, and may be, for example, steel.

[0019] The shape of the workpiece is not particularly limited, and can be any shape such as a plate, a cylinder, or a column. The shape of the surface of the workpiece is also not limited, and can be either flat or curved. That is, the present invention can be applied to both grinding flat surfaces and grinding curved surfaces.

[0020] In the following example, the case where the surface of a metal material is ground will be mainly described, but in the grinding device and grinding method of the present invention, the material to be ground is not limited to a metal material.

[0021] [Grinding Apparatus] First, the grinding apparatus of the present invention will be described. Fig. 1 shows the overall configuration of a grinding apparatus 1 for grinding the surface of a metal material as an example. The grinding apparatus 1 includes a grinding wheel 2, a grinder 3, a robot arm 4, and a control means (not shown).

[0022] The grinding member, grindstone 2, is pressed against the surface of the metal material to perform grinding. Here, in the present invention, the grinding member is not limited to a grindstone, and may be any member that grinds the surface of a metal surface. The shape of the grinding member is preferably circular or circular with a hole in the center.

[0023] In the present invention, the material of the grinding member is not limited. However, if the grinding member has elasticity, the deformation behavior of the grinding member will differ between pull grinding and push grinding, which will be described later, resulting in differences in contact area and grinding ability. Therefore, it is preferable that the grinding member does not have elasticity. Furthermore, the grain size of the abrasive grains of the grinding member is not particularly limited, but #14 to #60 is preferred.

[0024] The rotation axis of the grinding member extends in a direction inclined relative to the surface of the metal material, and since the rotation axis is not parallel to the surface of the metal material, a so-called vertical axis type grinding device and grinding member can be suitably used.

[0025] The grinding wheel 2 is detachably attached to the grinder 3 as the rotating means so that it can rotate about a rotation axis. Thus, in the present invention, the grinding device is equipped with a rotating means that rotates the grinding member about a rotation axis. The rotating means can be a grinder, but is not limited to this, and any device that can rotate a grinding member about a rotation axis and perform grinding, such as a belt sander, can be used.

[0026] The robot arm 4 serving as the moving means has the grinding wheel 2 disposed at its tip and moves the grinding wheel 2 relative to the surface of the metal material via the grinder 3. The moving means is not limited to a robot arm as long as it can move the grinding wheel 2 relative to the surface of the metal material. For example, a Cartesian robot, a SCARA robot, or the like may be used.

[0027] The control means controls the robot arm 4 and the grinder 3. The control means is configured to perform pull grinding and push grinding, which will be described later. Note that a preferred embodiment of the control means can be the same as a preferred embodiment of the grinding method, which will be described later.

[0028] The control means may include, for example, a processor, a memory unit, an input unit, and an output unit. These do not need to be provided integrally, but may be provided separately. The control means may also be composed of a movement control means for controlling the movement means and a rotation control means for controlling the rotation means. Furthermore, it does not matter whether the control is wireless or wired.

[0029] [Grinding Method] A grinding method executed by the grinding device according to this embodiment will be described below. The grinding method according to one embodiment of the present invention includes a pull grinding step in which pull grinding is performed and a push grinding step in which push grinding is performed.

[0030] (Pull grinding and push grinding) Pull grinding is a method of grinding the surface of a metal material by rotating the grinding member and moving the grinding member in the feed direction while keeping the rear end of the grinding member in contact with the surface of the metal material. On the other hand, push grinding is a method of grinding the surface of a metal material by rotating the grinding member and moving the grinding member in the feed direction while keeping the front end of the grinding member in contact with the surface of the metal material. The feed direction refers to the direction of movement of the grinding member relative to the surface of the metal material.

[0031] 2(a) and 2(b) show specific situations of pull grinding and push grinding. As shown in Fig. 2(a), in pull grinding, the grinding member is moved in the direction of a grinding locus 6 while rotating, thereby grinding the surface 5 of the metal material. As shown in Fig. 2(b), in push grinding, the grinding member is moved in the direction of a grinding locus 7 while rotating, thereby grinding the surface 5 of the metal material.

[0032] Here, pull grinding and push grinding differ in which part of the grinding member comes into contact with the surface of the metal material. Specifically, in the case of push grinding, at least the peripheral side surface of the grinding wheel 2 comes into contact with the unground portion of the surface 5 of the metal material, and in some cases, a portion of the underside of the grinding wheel 2 closer to the edge also comes into contact (contact range 9). On the other hand, in the case of pull grinding, although the peripheral side surface does not come into contact in principle, a wider area (contact range 8) of the underside of the grinding wheel 2 comes into contact with the unground portion of the surface 5 of the metal material, up to a portion closer to the rotation axis than in the case of push grinding.

[0033] Combining pull grinding and push grinding can improve the life of the grinding members compared to grinding using only one of the grinding methods, pull grinding or push grinding. This is thought to be because switching between push grinding and pull grinding allows different parts of the grinding wheel to come into contact with the surface of the metal material, making clogging and dulling less likely to occur. As a specific example, Figure 3 shows the results of comparing the change in grinding depth relative to the cumulative grinding area when grinding using pull grinding alone and when grinding using pull grinding and push grinding with reciprocating grinding, as described below. It can be seen that when grinding using pull grinding and push grinding, the tendency for the grinding depth to decrease is smaller than when grinding using pull grinding alone, and clogging and dulling are less likely to occur even when grinding is continued.

[0034] (Grinding Depth) In order to obtain a smoother finished surface, it is preferable to keep the difference in grinding depth between pull grinding and push grinding within a predetermined value. Specifically, the average grinding depth d ｐｕｌｌ and the average grinding depth d in the push grinding process ｐｕｓｈ The formula |d ｐｕｌｌ -d ｐｕｓｈ | / d ｐｕｌｌ It is preferable that the amount represented by the formula (1) is 0.30 or less. The lower limit of the amount is not limited, and it can be, for example, 0 or more.

[0035] Here, the average grinding depth of the entire grinding surface in the pull grinding process is d ｐｕｌｌ The ground surface includes the area ground by both push grinding and pull grinding. ｐｕｓｈ The same is true for .

[0036] The difference in grinding depth between pull grinding and push grinding can be reduced by adjusting at least one of the contact angle and feed rate of the grinding wheel 2. A specific adjustment method will be described below.

[0037] As described above, the area of ​​the grinding wheel 2 that comes into contact with the surface 5 of the metal material during grinding (contact area) differs between pull grinding and push grinding. Therefore, the contact angle θ between the grinding wheel 2 and the surface 5 of the metal material shown in FIGS. 2(a) and 2(b) ｐｕｌｌ and θ ｐｕｓｈ Regarding θ ｐｕｌｌ = θ ｐｕｓｈ Under these conditions, the area (contact area) of contact range 9 is smaller than that of contact range 8. In other words, when grinding is performed under the same conditions, the pressing force of the grinding wheel 2 per unit area is greater in push grinding, and a difference in grinding ability occurs between pull grinding and push grinding, which may result in steps remaining on the surface of the metal material after grinding.

[0038] So, for example, θ ｐｕｓｈ θ ｐｕｌｌ It is preferable to increase the area of ​​contact area 9 by making it smaller than , so that it approaches the area of ​​contact area 8. In this way, by making the areas of contact area 8 and contact area 9 approximately the same, it is possible to reduce the difference in contact pressure and the difference in grinding depth.

[0039] In addition, it is advisable to make the feed rate in pull grinding slower than that in push grinding, which increases the contact time between the grinding wheel 2 and the surface 5 of the metal material in pull grinding, thereby lengthening the grinding time and reducing the difference in grinding depth.

[0040] (Grinding trajectory) When grinding the surface 5 of a metal material using the grinding device 1 described above, the grinding trajectory is not limited and can be set appropriately depending on the shape of the metal material, the grinding range, etc. In an example of a grinding method shown in Figure 4, the grinding trajectory is composed of a forward grinding trajectory 6 (two solid arrows) for grinding by pull grinding, a return grinding trajectory 7 (one dashed arrow) for grinding by push grinding, and a return grinding trajectory 10 (two dashed arrows) connecting the grinding trajectory 6 and the grinding trajectory 7. By grinding according to the grinding trajectories, the entire grinding range 11 can be ground. The grinding trajectory 6 is a trajectory that runs along a first direction on the surface of the metal material, and the grinding trajectory 7 is a trajectory that runs along a second direction opposite to the first direction. In this way, by making the feed direction in the pull grinding process and the feed direction in the push grinding process opposite, grinding can be performed in a reciprocating manner, thereby reducing the time spent in non-grinding operations and improving the efficiency of the grinding operation.

[0041] The lengths of the grinding path 6 and the grinding path 7 can be determined based on the length 12 of the grinding range 11 along the first direction and the second direction.

[0042] The grinding trajectory 6 and the grinding trajectory 7 are spaced apart in the width direction by a gap 13, which can be determined as appropriate. However, to further prevent insufficient grinding, it is preferable to determine the gap 13 so that the grinding surface in the pull grinding process overlaps with the grinding surface in the push grinding process. In this case, it is preferable to set the grinding trajectory so that the width of the overlapping portion between the grinding surface in the adjacent pull grinding process and the grinding surface in the push grinding process (lap width) falls within a predetermined range. When setting the grinding trajectory, the length of the gap 13 can be calculated by subtracting the lap width from the average (average grinding width) of the grinding widths in the pull grinding process and the push grinding process. Specifically, it is preferable to set the grinding trajectory so that the lap width is 30% or more of the average grinding width. Note that the grinding trajectory may be set so that the lap width is less than 100% of the average grinding width. The lapping width can be a predicted value determined based on the predicted grinding width. The method for predicting the grinding width is not limited, but it can be predicted in advance from the type of grinding member, grinding conditions other than the grinding trajectory, past operating conditions, etc.

[0043] (Fold-back grinding) The grinding method according to the present invention preferably includes a flip-back grinding step between the pull grinding step and the push grinding step. The flip-back grinding step is a step of switching between the pull grinding step and the push grinding step while continuing grinding. Hereinafter, the grinding performed in the flip-back grinding step will be referred to as flip-back grinding. By including the flip-back grinding step, the contact and separation operations of the grinding member are eliminated, and steps at the edge of the grinding surface can be further suppressed. Note that the flip-back grinding step is not essential, and in that case, the grinding member may be temporarily separated from the surface of the metal material between pull grinding and push grinding.

[0044] In one embodiment of the present invention, the grinding wheel 2 is moved along a turn-back grinding trajectory 10 in the turn-back grinding process. FIG. 5 shows an enlarged view of the turn-back portion as an example of a grinding method. In one embodiment, the turn-back grinding trajectory 10 is a parabola connecting a start point 15, a turn-back point 16, and an end point 17. The grinding trajectory in the turn-back grinding process is preferably a curved line such as a parabola or a circular arc from the viewpoint of obtaining a smoother finished surface. Furthermore, the start point 15 coincides with the end point of the grinding trajectory 6 before the turn-back, and the end point 17 coincides with the start point of the grinding trajectory 7 after the turn-back. That is, the distance of the turn-back grinding trajectory 10 in a direction perpendicular to the first and second directions (upward in FIG. 5 ) coincides with the interval 13. Furthermore, in FIG. 5 , the distance between the line connecting the start point 15 and the end point 17 and the turn-back point 16 is shown as the turn-back path length 14. In FIG. 5, the distance between the start point 15 and the turn-back point 16 in the direction parallel to the first direction and the second direction, and the distance between the end point 17 and the turn-back point 16, are equal to the turn-back path length 14.

[0045] (Feed rate, length of return path) In order to obtain a smoother finished surface, it is preferable to make shallow the step that occurs at the boundary between the ground surface ground in the return grinding process and the unground portion of the surface of the metal material, specifically, it is preferable to make it 0.4 mm or less. The lower limit of the depth of the step is not particularly limited, and can be, for example, 0 mm or more.

[0046] Here, the step is a value calculated as follows: First, a turn-around point is determined from the return grinding trajectory. Then, for the metal material after grinding, the boundary is calculated by identifying the grinding surface that was ground in the return grinding process and the unground portion of the surface of the metal material. Next, a height profile is obtained on a line segment that includes the turn-around point, is parallel to the first direction and the second direction, and crosses the boundary, and the slope of the profile is corrected as necessary. Then, the step is calculated as the difference in height between before and after the boundary. If return grinding is performed multiple times, the step is expressed as the average of the step calculated for all return points.

[0047] In the return grinding process, the step can be made shallower by adjusting at least one of the feed speed of the grinding member and the length of the return path. Here, the feed speed in the return grinding process refers to the speed in the direction along the return grinding path.

[0048] 6 and 7 show the change in the step with respect to the feed rate of the grinding wheel 2 and the return path length 14 in the return grinding process.

[0049] 6, it can be seen that the step gradually becomes shallower as the feed rate of the grinding wheel 2 increases. This is thought to be because increasing the feed rate shortens the time that the grinding wheel 2 remains at the turning point 16, thereby reducing the grinding depth. Therefore, it is preferable to increase the feed rate.

[0050] Furthermore, by making the feed rate of the return grinding closer to the feed rates of the pull grinding and the push grinding, the step can be further suppressed. Therefore, to obtain an even smoother finished surface, the feed rate in the return grinding step is preferably 70% or more of the feed rate in the pull grinding step and 70% or more of the feed rate in the push grinding step. Similarly, the feed rate in the return grinding step is preferably 130% or less of the feed rate in the pull grinding step and 130% or less of the feed rate in the push grinding step.

[0051] 7, it can be seen that the step gradually becomes shallower as the return path length 14 is increased. This is thought to be because, by increasing the return path length 14, the radius of curvature of the return grinding path 10 at the return point 16 becomes smaller, and the residence time of the grinding wheel 2 at the return point 16 becomes shorter. Therefore, it is preferable to increase the return path length 14.

[0052] On the other hand, if the return path length 14 is too long, there is a concern that the operating time of the return grinding step will be long. Therefore, it is preferable to determine the return path length 14 so that the ratio of the operating time of the return grinding step to the total operating time of the pull grinding step, the push grinding step, and the return grinding step is 1% or more and 10% or less.

[0053] [Method for manufacturing a metal product] The method for manufacturing a metal product according to the present invention is a method for grinding the surface of a metal material as a grinding target material using the grinding device described above. By manufacturing a metal product using the manufacturing method, the life of the grinding member can be extended. Furthermore, since clogging and dulling of the grinding member can be prevented, poor finished surfaces of the metal product can be suppressed and the finished surface can be made smooth. The specific manufacturing method can be the same as the grinding method described above.

[0054] REFERENCE SIGNS LIST 1 Grinding device 2 Grinding wheel 3 Grinder 4 Robot arm 5 Surface of metal material 6, 7 Grinding path 8, 9 Contact area 10 Turning grinding path 11 Grinding area 12 Length 13 Spacing 14 Turning path length 15 Starting point 16 Turning point 17 End point

Claims

1. A grinding method for grinding the surface of a workpiece using a grinding member that extends in a direction in which its rotation axis is inclined with respect to the surface of the workpiece, A pull grinding process is performed by rotating the grinding member and moving the grinding member in the feed direction while keeping the rear end of the grinding member in contact with the surface of the material to be ground, thereby grinding the surface of the material to be ground. A push grinding process is performed by rotating the grinding member and moving the grinding member in the feed direction while keeping the front end of the grinding member in contact with the surface of the material to be ground, thereby grinding the surface of the material to be ground. A sharp grinding method.

2. The average grinding depth d of the surface of the workpiece in the pull grinding process. ｐｕｌｌ And, the average grinding depth d of the surface of the workpiece in the push grinding process. ｐｕｓｈ Requires | d ｐｕｌｌ -d ｐｕｓｈ | / d ｐｕｌｌ The grinding method according to claim 1, wherein the coefficient is 0.30 or less.

3. The feed direction in the pull grinding process is the first direction of the surface of the workpiece to be ground. The feed direction in the push grinding process is a second direction opposite to the first direction. The process further includes a reverse grinding step between the pull grinding step and the push grinding step, in which the pull grinding step and the push grinding step are switched while continuing to grind the surface of the workpiece. The grinding method according to claim 1.

4. The feed direction of the pull grinding step is the first direction of the surface of the workpiece to be ground, The feed direction in the push grinding process is a second direction opposite to the first direction. The process further includes a reverse grinding step between the pull grinding step and the push grinding step, in which the pull grinding step and the push grinding step are switched while continuing to grind the surface of the workpiece. The grinding method according to claim 2.

5. The grinding method according to claim 3, wherein the depth of the step difference that occurs at the boundary between the ground surface that has been ground in the folding grinding step and the portion of the surface of the material to be ground that has not been ground is 0.4 mm or less.

6. The grinding method according to claim 4, wherein the depth of the step that occurs at the boundary between the ground surface that has been ground in the folding grinding step and the portion of the surface of the material to be ground that has not been ground is 0.4 mm or less.

7. A grinding method according to any one of claims 1 to 6, wherein the grinding trajectory is set such that the width of the overlapping portion between the grinding surface in the adjacent pull grinding step and the grinding surface in the push grinding step is 30% or more of the average of the grinding width in the pull grinding step and the grinding width in the push grinding step.

8. A grinding device for grinding the surface of a workpiece, A grinding member extending in a direction in which the axis of rotation is inclined with respect to the surface of the material to be abraded, A means for moving the grinding member, A rotating means for rotating the grinding member around the rotation axis, The system comprises control means for controlling the moving means and the rotating means, The control means is Pull grinding is performed by rotating the grinding member and moving the grinding member in the feed direction while keeping the rear end of the grinding member in contact with the surface of the material to be ground, thereby grinding the surface of the material to be ground. Push grinding is performed by rotating the grinding member and moving the grinding member in the feed direction while keeping the front end of the grinding member in contact with the surface of the material to be ground, thereby grinding the surface of the material to be ground. A grinding device configured to perform the following actions.

9. A method for manufacturing a metal product, comprising grinding the surface of a metal material to be ground using the grinding apparatus described in claim 8.