JP3705236B2 - Grinding apparatus and grinding method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a grinding apparatus and a grinding method for grinding a workpiece by rotating relative to the grinding wheel while rotating the workpiece around a central axis.
[0002]
[Prior art]
Conventionally, in order to grind a cylindrical workpiece or a camshaft used for an automobile engine, a grinding apparatus that performs grinding with a grindstone that rotates at high speed while rotating the workpiece around its central axis is known. (For example, Unexamined-Japanese-Patent No. 10-225856 etc.).
[0003]
Regarding the relationship between the rotation direction of the workpiece and the rotation direction of the grindstone, there are two possible ones: the one shown in FIG. 4A (up cut) and the one shown in FIG. 4B (down cut). Grinding was performed by up-cutting (A), which can be ground with relatively good surface accuracy.
[0004]
[Problems to be solved by the invention]
When grinding is performed with such a grinding apparatus, the sharpness of the grindstone gradually decreases, and slipping easily occurs. When slipping occurs, heat is generated and grinding burn occurs. For this reason, it is necessary to perform dressing frequently and the grinding efficiency cannot be increased.
[0005]
In view of the above problems, an object of the present invention is to suppress grinding burn and improve grinding efficiency, and to obtain good finished surface accuracy.
[0006]
[Means for Solving the Problems]
In order to solve this problem, the inventors of the present application have intensively studied and studied various principles of grinding burns and methods for suppressing them. As a result, as shown in FIGS. 5 (A) and 5 (B), the grinding burn occurs when one abrasive grain hits the workpiece and starts grinding, because the bite angle Ig1 is small and the abrasive grain is machined. There must be a region S1 that cannot slide into the object and slides on the workpiece surface. Further, it has been found that the main reason is that the sliding causes the abrasive grains to be flattened by abrasion as shown in FIG.
[0007]
On the other hand, according to the down cut as shown in FIG. 6 (B), since the bite angle Ig2 is large as shown in FIGS. 6 (A) and 6 (B), the abrasive grains are applied until they come off after hitting the workpiece. Always cut into the workpiece. For this reason, although the heat | fever by sliding is hard to generate | occur | produce, since the abrasive grain has cut | disconnected also in area | region S2 used as the workpiece surface after grinding, a surface precision falls rather than the case by an upcut. For this reason, it is not appropriate to perform grinding only by down-cutting.
[0008]
Accordingly, the inventors have obtained the knowledge that if only rough grinding is performed by down-cutting and finish grinding is performed by up-cutting, optimum grinding can be performed taking advantage of each advantage, and the present invention has been achieved. It was.
[0009]
That is, by performing rough grinding by down-cutting, it is possible to reduce slip of abrasive grains and suppress grinding burn. On the other hand, the surface accuracy of the machined surface after rough grinding is not good, but there is no problem because it is scraped off during subsequent finish grinding. In addition, since the finish grinding is performed by up-cutting, the finished surface accuracy equivalent to that of the conventional grinding method can be obtained. This is particularly effective when grinding a low-rigidity steel material.
[0010]
Based on this knowledge, in the inventions according to claims 1 and 3, the workpiece driving means for rotating the workpiece around its central axis, the grinding wheel base for supporting the grinding wheel, and the grinding wheel for rotationally driving the grinding wheel In a grinding apparatus or method for grinding a workpiece with the grinding wheel, the vehicle and the grinding wheel are provided with a vehicle driving means, and a relative movement means for relatively moving the workpiece and the grinding wheel base. After rough grinding by down-cut with the same rotation direction of the car, either the rotation direction of the workpiece by the workpiece driving means or the rotation direction of the grinding wheel by the grinding wheel driving means is switched to perform grinding. Finish grinding is performed by up-cut in which the workpiece and the grinding wheel rotate in opposite directions.
[0011]
As a result, rough grinding, which requires high efficiency grinding for more grinding allowances, is performed by down-cutting, so grinding burn is unlikely to occur and finish grinding, which must be ground with high precision, is performed by up-cutting. Good finish surface accuracy can be obtained.
[0012]
In the inventions according to claims 2 and 4, the workpiece driving means for rotating the workpiece around its central axis, and the first and second grinding wheel platforms for pivotally supporting the first and second grinding wheels, respectively. Grinding wheel driving means for rotationally driving the first and second grinding wheels, and relative movement means for relatively moving the workpiece and the first and second grinding wheel platforms, In the grinding method of grinding by the first and second grinding wheels, rough grinding of the workpiece by the first grinding wheel is performed, and the rotation direction of the workpiece and the first grinding wheel at a grinding point is the same direction. It is decided to carry out the final grinding of the workpiece by the second grinding wheel with an upcut in which the rotation direction of the workpiece and the second grinding wheel at the grinding point is opposite. .
[0013]
As a result, in addition to the operations and effects of the inventions of claims 1 and 3, rough grinding and finish grinding can be performed simultaneously by the first and second grinding wheels, so that the operating efficiency is further increased. Can do.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. Here, a specific example is given and demonstrated about the case where this invention is applied to the grinding device which grinds the camshaft used for the engine of a motor vehicle. FIG. 1 shows a schematic configuration diagram of a camshaft grinding apparatus in the present embodiment. As shown in FIG. 1, a Z-axis table 10 is installed on Z-axis guide rails 2a and 2b in the Z-axis direction installed on a bed 1 of a grinding apparatus. The table 10 is slidable in the Z-axis direction by the ball screw 3. A grinding wheel base 20 is installed on the X-axis guide rails 11 a and 11 b of the Z-axis table 10. The grinding wheel base 20 is slidable in the X-axis direction by the ball screw 12. On the grinding wheel base 20, a grinding wheel 31 and a grinding wheel drive motor 32 that pivotally supports these wheels are installed.
[0015]
Spindle heads 40a and 40b are installed in front of the grinding wheel head 20 in the X-axis. A steel camshaft 80, which is a workpiece, is rotatably supported by a chuck or the like provided on the headstocks 40a and 40b. The spindle heads 40a and 40b are provided with spindle motors 50a and 50b that rotate the camshaft 80 around the central axis. The spindle motors 50a and 50b are controlled to the same phase in complete synchronization.
[0016]
The Z-axis ball screw 3 is rotationally driven by a Z-axis table motor 51. The X-axis ball screw 12 is driven to rotate by a grindstone motor 52. Each of these motors (spindle motors 50a and 50b, Z-axis table motor 51, and grindstone motor 52) is a servo motor capable of high-precision positioning, and is controlled by a numerical controller 61 built in the control panel 60. The numerical controller 61 stores in advance an NC program, parameters, and the like necessary for grinding each machining portion of the camshaft 80.
[0017]
The grinding wheel drive motor 32 is a motor that can rotate at high speed with high torque, and generates a rotational force by a current supplied from a driver 62 built in the control panel 60. Information on the current value output by the driver 62 is sent to the numerical controller 61.
[0018]
Next, a grinding method using the grinding apparatus having the above-described configuration will be described with reference to the flowchart of FIG. In the following, S * (* = 102, 104,...) Represents each step in the flowchart. For the sake of convenience, the cam 81 at the right end of the camshaft 80 in the drawing is designated as a grinding location 1 and the pair of cams 82 adjacent to the left is designated as a grinding location 2. Hereinafter, similarly, it will be set as the grinding location 3,4 ... 7,8, and shall grind in this order. Each of these grinding points is represented as a grinding point n (n = 1 to 8) in the flowchart of FIG.
[0019]
The flowchart of FIG. 2 is a flowchart showing an example of a schematic processing procedure performed by the numerical controller 61 when grinding one camshaft. In this flowchart, n is initialized to 1 in S102. This means that the grinding point 1 is ground first. In the next S104, an instruction is sent to the driver 62 to start the rotation of the grinding wheel.
[0020]
In S106, the spindle motors 50a and 50b start to rotate in the W2 direction, and in this state, the Z-axis table motor 51 and the grinding wheel base motor 52 are controlled in S108 to move the camshaft 80 and the grinding wheel base 20 relative to each other and perform rough grinding. I do. At this time, since the rotation direction of the workpiece at the grinding point and the grinding wheel is the same direction, grinding is performed by down-cutting.
[0021]
When the rough grinding is completed, the rotation direction of the spindle motors 50a and 50b is reversed in S110, and the rotation is started in the W1 direction. In this state, by controlling the Z-axis table motor 51 and the grindstone motor 52 in S112, the camshaft 80 and the grindstone table 20 are relatively moved to perform finish grinding. At this time, since the rotation direction of the work piece and the grinding wheel at the grinding point is opposite, grinding is performed by up-cutting.
[0022]
When finish grinding is completed, it is determined whether or not n is 8 in S114. If n = 8, n is incremented by 1 and the next grinding point is ground. If n = 8, it is determined that the grinding of all the grinding points is completed, and the grinding is finished.
[0023]
By performing grinding in this way, it is difficult to generate grinding burn because rough grinding, which requires more grinding to be performed with high efficiency, is performed with a down cut, and relatively less grinding allowance is highly accurate. Since the finish grinding that must be ground is up-cut, good finished surface accuracy can be obtained.
[0024]
In the above description, the embodiment in which the rotation direction of the grinding wheel is fixed and the rotation direction of the workpiece is switched has been described. On the contrary, the rotation direction of the workpiece is fixed and the rotation direction of the grinding wheel is changed. The same effect can be obtained even if the down cut and the up cut are switched by switching.
[0025]
Further, as described above, the abrasive grains hit the work piece with a large biting angle during the down cut, so that the abrasive grains are crushed at a certain rate due to the impact at this time (FIG. 6C). For this reason, there exists an effect | action similar to dressing the abrasive grain planarized at the time of an up cut, the dressing interval which performs dressing can be extended, and there also exists an effect which raises grinding efficiency.
[0026]
Next, a second embodiment of the present invention will be described based on the drawings. The configuration example of the grinding apparatus in the present embodiment is shown in FIG. 3, and the difference from the first embodiment is that two grinding wheel bases that can support and rotate the grinding wheel are provided, This is because the grindstone platform can be independently moved relative to the workpiece. As shown in FIG. 3, the grinding apparatus according to the present embodiment includes grinding wheels 31a and 31b, one of which is used for rough grinding and the other is used for finish grinding. The grinding wheel for rough grinding performs rough grinding with a down cut in which the rotation direction of the workpiece 80 and the grinding wheel at the grinding point is the same direction, and the grinding wheel for finish grinding rotates the workpiece 80 and the grinding wheel at the grinding point. Finish grinding with up-cut in the opposite direction.
[0027]
As a result, it is possible to finish grinding with up-cut while performing rough grinding with down-cut, so in addition to the action and effect of the first embodiment, the grinding of the workpiece can be completed in a short time, and the operating efficiency is improved. Can be raised.
[0028]
【The invention's effect】
As described above, in the inventions according to claims 1 and 3, the workpiece driving means for rotating the workpiece around the central axis thereof, the grinding wheel base for pivotally supporting the grinding wheel, and the grinding wheel being rotationally driven. A grinding wheel driving means, a relative movement means for relatively moving the workpiece and the grinding wheel base, and a grinding apparatus or a grinding method for grinding the workpiece by the grinding wheel. After rough grinding by down-cut with the same direction of rotation of the grinding wheel, switching is performed between the rotation direction of the workpiece by the workpiece driving means and the rotation direction of the grinding wheel by the grinding wheel driving means. Since the finish grinding is performed by the up-cut in which the rotation direction of the workpiece and the grinding wheel is opposite to each other at the grinding point, grinding burn hardly occurs and a good finished surface precision is obtained. It is possible to obtain. In addition, the dressing interval can be extended and the grinding efficiency can be improved.
[0029]
In the inventions according to claims 2 and 4, the workpiece driving means for rotating the workpiece around its central axis, the first and second grinding wheel platforms for pivotally supporting the first and second grinding wheels, respectively. Grinding wheel driving means for rotationally driving the first and second grinding wheels, and relative movement means for relatively moving the workpiece and the first and second grinding wheel platforms, wherein the workpiece is In the grinding method of grinding with the first and second grinding wheels, rough grinding of the workpiece by the first grinding wheel is performed so that the rotation direction of the workpiece and the first grinding wheel at a grinding point is the same direction. Since it is performed by down-cutting, the finish grinding of the workpiece by the second grinding wheel is performed by up-cut in which the rotation direction of the workpiece and the second grinding wheel at the grinding point is opposite, In the operation and effect of the inventions of claims 1 and 3 For example, since the rough grinding and finish grinding the first and second grinding wheel can be carried out simultaneously in parallel, it can be completed grinding of the workpiece in a short time.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration in a first embodiment of the present invention.
FIG. 2 is a flowchart showing a procedure of a grinding method according to the first embodiment of the present invention.
FIG. 3 is a diagram showing a schematic configuration in a second embodiment of the present invention.
FIG. 4 is an explanatory diagram showing an up cut and a down cut.
FIG. 5 is an explanatory view showing an example in the case of up-cut grinding while rotating a cylindrical workpiece.
FIG. 6 is an explanatory diagram showing an example of down-cut grinding while rotating a cylindrical workpiece.
[Explanation of symbols]
31, 31a, 31b Grinding wheel 80 Camshaft (workpiece)
32 grinding wheel drive motors 50a and 50b spindle motor 60 control panel 61 numerical control device 62 driver

Claims (4)

Relative movement of the workpiece driving means for rotating the workpiece around its central axis, a grinding wheel base for pivotally supporting the grinding wheel, a grinding wheel driving means for rotationally driving the grinding wheel, and the workpiece and the grinding wheel base A grinding device for grinding the workpiece by the grinding wheel,
Rough grinding means for performing rough grinding by down-cut in which the rotation direction of the workpiece and the grinding wheel at the grinding point is the same direction;
Finish grinding means for performing finish grinding by up-cut in which the rotation direction of the workpiece and the grinding wheel at the grinding point is opposite;
A switching control means for switching between a rotation direction of the workpiece by the workpiece driving means and a rotation direction of the grinding wheel by the grinding wheel driving means when performing finish grinding following the rough grinding. A characteristic grinding device. A workpiece driving means for rotating the workpiece around its central axis, first and second grinding wheel platforms for supporting the first and second grinding wheels, respectively, and the first and second grinding wheels Grinding comprising grinding wheel driving means for driving, and relative movement means for relatively moving the workpiece and the first and second grinding wheel platforms, and grinding the workpiece by the first and second grinding wheels In the device
Rough grinding means for performing rough grinding of the workpiece by the first grinding wheel by down-cut in which the rotation direction of the workpiece and the first grinding wheel at the grinding point is the same direction;
Finish grinding of the workpiece by the second grinding wheel is provided with a finish grinding means for performing up-cutting in which the workpiece at the grinding point and the rotation direction of the second grinding wheel are opposite to each other. Grinding equipment. Relative movement of the workpiece driving means for rotating the workpiece around its central axis, a grinding wheel base for pivotally supporting the grinding wheel, a grinding wheel driving means for rotationally driving the grinding wheel, and the workpiece and the grinding wheel base A grinding method for grinding the workpiece by the grinding wheel,
After rough grinding is performed by down-cutting in which the workpiece and the grinding wheel are rotated in the same direction at a grinding point, the workpiece is rotated by the workpiece driving means, and the grinding wheel is rotated by the grinding wheel driving means. A grinding method characterized in that any one of directions is switched, and finish grinding is performed by up-cut in which the rotation direction of the workpiece and the grinding wheel at the grinding point is opposite. A workpiece driving means for rotating the workpiece around its central axis, first and second grinding wheel platforms for supporting the first and second grinding wheels, respectively, and the first and second grinding wheels Grinding comprising grinding wheel driving means for driving, and relative movement means for relatively moving the workpiece and the first and second grinding wheel platforms, and grinding the workpiece by the first and second grinding wheels In the method
Rough grinding of the workpiece by the first grinding wheel is performed by a down cut in which the rotation direction of the workpiece and the first grinding wheel at the grinding point is the same direction,
A grinding method, wherein the finish grinding of the workpiece by the second grinding wheel is performed by up-cut in which the rotation direction of the workpiece and the second grinding wheel at a grinding point is opposite.

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