JP2008137094A - Grinding method for workpiece such as material for long drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently grind even a thin and long workpiece w having a small diameter such as a material for a long drill having, for example, an L/D ratio (L = length of a section to be ground of the workpiece/D = diameter of the section to be ground) of about 8 mm or less in diameter and 320 mm or more in length to set the amount of run-out in rotation supported with both ends after working to, for example, 5 μm or less. <P>SOLUTION: This grinding method comprises: a process of grinding an outer peripheral face being the section to be ground of the thin and long workpiece w having a small diameter such as the material for the long drill into a right cylindrical face having a uniform diameter by a grinding wheel; and a process of grinding a section except both end parts of the section to be ground into a middle recessed shape having a smaller diameter than those of both end parts by operating the grinding wheel 1 to pass a specific locus of travel to the workpiece w. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a workpiece grinding method capable of grinding an outer peripheral surface, which is a portion to be ground, of a small-diameter elongated workpiece such as a material for a long drill into an accurate straight shape.

  When the outer peripheral surface, which is the grinding target area, of a small-diameter and long-shaped workpiece (such as a material having a diameter of 10 mm and a length of about 320 mm) such as a long drill material is processed with a centerless cylindrical grinder, the processed workpiece However, in many cases, the required deflection accuracy cannot be obtained due to the initial bending or elasticity of the workpiece.

  For example, when an elongated workpiece having a length of about 300 mm is ground with a centerless grinder, for example, in the case of a runout during rotation of the workpiece after the processing, an allowable range (for example, in the case of a runout associated with both-end support rotation described later) It can be suppressed within 5 μm or less) at present when the workpiece diameter is approximately 10 mm or more.

  Using a centerless cylindrical grinder as disclosed in Patent Document 1 to process a small-diameter elongated workpiece (the initial runout is a certain level or more) having a diameter of about 8 mm and a length of about 320 mm. In FIG. 11, when plunge processing is performed with a grinding wheel having a width equal to or greater than the workpiece length and an adjustment wheel, the workpiece w that is forcibly straightened between the grinding wheel 1 and the adjustment wheel 2 during the processing as shown in FIG. However, under the free state after processing, a phenomenon occurs in which it is restored to a bent state (exaggerated for convenience of explanation) as shown by the dotted line d1 due to its own elasticity. 12, when traversing is performed using a grinding wheel 1 having a width shorter than the workpiece w length, in addition to the phenomenon at the time of the previous plunge machining, the workpiece w being machined is bent (exaggerated for convenience of explanation). As a result, the bending of the end portion away from the outer peripheral surface of the adjustment wheel 2 is not effectively corrected, and as a result, it takes a long time under the optimum conditions. Even if the workpiece is processed, the amount of deflection associated with the rotation of both ends of the workpiece cannot be reduced to 6 μm or less.

Therefore, in order to ensure the deflection accuracy, for example, a material manufacturer, for example, processes a small and narrow workpiece having a diameter of 8 mm or less by using a cylindrical grinding machine to which steadying means and support rollers are added. . However, in this case, in order to reduce the escape amount due to the elastic bending of the workpiece being machined, it must be machined with a very small depth of cut so as not to generate a large grinding resistance. It is the actual situation that requires.
11 and 12, O1 is the rotation center line of the grinding wheel 1, and O2 is the rotation center line of the adjusting wheel 2.

As a known document of the centerless cylindrical grinder, there is a document as shown in Patent Document 1, and as a known document of the cylindrical grinder, there is a document as shown in Patent Document 2, and as a known document of a long drill. There exists a thing as shown to patent document 3.
JP 2005-46952 A JP-A-8-155833 JP 2003-53607 A

  The present invention has been made in view of the above-described problems. For example, the L / D ratio (= the length of the workpiece to be ground) such that the diameter is about 8 mm or less and the length exceeds about 320 mm. L / Even for a small and narrow workpiece such as a long drill material having a diameter D) of the portion to be ground, it is efficient so that the amount of run-out associated with the rotation of both ends after the machining is, for example, 5 μm or less. This makes it possible to grind.

In order to achieve the above object, according to a first aspect of the present invention, as described in claim 1, an outer peripheral surface, which is a portion to be ground of a small-diameter elongated workpiece such as a long drill material, is a straight cylinder having a uniform diameter. In the process of grinding to the surface, the process is performed so as to insert a step of grinding the portion excluding both ends of the portion to be ground into a concave shape having a smaller diameter than the both ends. Is.
As described in claim 2, the present invention can be carried out using a cylindrical grinder provided with a grinding wheel, a main shaft, a main shaft center, and a tailstock center and provided with a steady-rest means.

Next, according to a second aspect of the present invention, as set forth in claim 3, the support roller and the grinding wheel can be rotated around a parallel center line and can be relatively displaced in the center line direction. A specific clamping state in which the outer peripheral surface, which is the part to be ground of a small-diameter elongated workpiece such as a long drill material, is sandwiched at a specific position by these support rollers and a grinding wheel. Then, the portion to be ground is ground into a concave shape, and then the grinding wheel is moved in a straight line in the center line direction to grind the outer peripheral surface to be ground. It is a characteristic to do.
At this time, as described in claim 4, the width of the grinding wheel is preferably 1/3 or less of the workpiece length.

The first and second inventions described above are preferably implemented as follows.
That is, as described in claim 5, it is carried out using a centerless cylindrical grinder equipped with an adjusting wheel, a grinding wheel, and a work support.

  In addition, as described in claim 6, the first step of grinding the portion to be ground into a concave shape and the second step of grinding the portion to be ground into a right cylindrical surface shape are repeated in this order an arbitrary number of times. To do.

According to the present invention described above, the following effects can be obtained.
That is, according to the first aspect of the present invention, for example, a long having an L / D ratio (= the length to be ground L / the diameter to be ground D) such that the diameter is about 8 mm or less and the length exceeds about 320 mm. As shown in FIG. 12, even a small-diameter elongated workpiece such as a drill material can be machined in a state where both ends of the workpiece are supported by a straight plane along the rotation center during machining. Therefore, it is possible to perform grinding efficiently so that the amount of runout accompanying the rotation of both ends after the workpiece is processed becomes, for example, 5 μm or less.

  Specifically, when a workpiece having a diameter of about 8 mm to 4 mm and a length of about 300 mm to 350 mm is ground so that the amount of run-out due to both-end support rotation after processing is 5 μm or less, the rough grinding is performed. It is possible to perform the processing from the beginning to the end of Sparking through Nakarikuken and Seiken in about ten minutes to several tens of minutes.

  According to the second aspect of the present invention, since the cylindrical grinder includes the steadying means, the invention according to the first aspect can be carried out without preparing a special dedicated machine, In addition to being supported by the spindle center and tailstock center so that it can rotate around a specific centerline, the workpiece can be rotated by the rotational force of the spindle, and the grinding wheel rotates relative to the workpiece rotation compared to a centerless cylindrical grinder. Since the arbitraryness of the speed is increased, it is effective for making the runout accuracy after processing extremely high.

  According to the third aspect, the same effect as in the case of the first aspect can be obtained with certainty.

  According to the fourth aspect of the present invention, the same effect as that of the third aspect of the present invention can be obtained, and the portion to be ground of the workpiece can be formed into a preferable concave shape and the grinding resistance during the workpiece processing can be reduced. Thus, the same effect as that of the first aspect of the invention can be obtained more effectively.

  According to the fifth aspect of the present invention, the adjusting wheel functions as a support roller, and the grinding wheel is replaced with one corresponding to the workpiece length without preparing a special dedicated machine. It becomes possible to implement this invention.

  According to the sixth aspect of the present invention, it is possible to easily change the runout accuracy after machining to an extremely high arbitrary level without changing other machining conditions.

Next, an embodiment of the present invention will be described in detail with reference to FIGS.
In carrying out the present invention, a centerless cylindrical grinder 100 is prepared. The grinder 100 may be the same as that disclosed in Patent Document 1, for example.

  As shown in FIGS. 1 and 2, the centerless cylindrical grinder 100 is adjusted so that the grinding wheel 1 is rotated about the rotation center line O1 in the left-right direction and the rotation center line O2 is rotated in the left-right direction. A vehicle (support roller) 2 and a work support member 3 are provided.

  The grinding wheel 1 is supported by a grinding wheel base 4, and the adjustment wheel 2 is supported by an adjustment wheel base 5. At this time, the grinding wheel head 4 is moved in the X-axis direction (front-rear direction) on the bed 7 by the operation of the servo motor 6, and the adjustment carriage 5 is moved in the Z-axis direction (left-right direction) on the bed 7. ) And is moved in the X-axis direction by the operation of the servo motor 9.

  In the centerless cylindrical grinding machine 100, the width a1 of the adjusting wheel 2 is equal to or larger than the entire length of the outer peripheral surface, which is a portion to be ground, of the small-diameter elongated workpiece w to be processed. Further, the width a2 of the grinding wheel 1 is made smaller than the entire length of the portion to be ground and is preferably maximized within a range where the portion to be ground can be ground into a concave shape as will be described later. For example, it is about 1/3 or less of the entire length of the portion to be ground.

  The operation of each part of the centerless cylindrical grinder 100 is controlled by a computer numerical control device (not shown). In the grinding machine 100, the adjusting wheel 2 is moved in the Z-axis direction via the intermediate platform 8, but the grinding wheel 1 may be moved in the Z-axis direction.

  After inputting a required program into the computer numerical control device, the centerless cylindrical grinder 100 is used to machine a small-diameter elongated workpiece w used for a long drill material or the like. FIG. 3 shows a flowchart for this processing, which will be described below with reference to this flowchart.

  First, in step s1, a single workpiece w is loaded onto the workpiece support member 3 by an automatic operation by a robot or set manually.

  Next, as shown in step s2, the size of the workpiece w (for example, the diameter D or the length L of the outer peripheral surface, which is a portion to be ground) is input to the above-mentioned numerical control device from the operation panel (not shown).

  Thereafter, as shown in step s3, the processing start button on the operation panel is pressed. As a result, the computer numerical control device operates each unit, and automatically performs the processing from steps s4 to s7.

  In step s4, it is determined whether or not it is necessary to execute a center recess traverse control for traversing the portion to be ground into a center recess in order to ensure the required runout accuracy of the workpiece w on the workpiece support member 3. To do.

The discrimination criterion at this time can be arbitrarily determined. For example, it is as follows.
That is, when the L / D ratio, which is the ratio between the diameter D and the length L, of the workpiece w to be ground is equal to or greater than a specific value, it is determined as “yes”, otherwise, “no”. Try to judge.

  Since the specific value of the L / D ratio represents the ease of bending of the workpiece w, it should be a different value in relation to the change in the material of the workpiece w and the size of the diameter D of the portion to be ground. Specifically, for example, if the workpiece w is a steel material, for example, when the diameter D is 8 mm, it is, for example, “40”, when the diameter D is 6 mm, it is, for example, “30”, and the diameter is 4 mm. For example, “20” is set.

  The specific value is determined in advance by experiment or the like for each material of the workpiece w and the diameter L of the portion to be ground. Thus, data defining the specific value corresponding to each diameter L is the computer numerical control. Pre-input to the device.

  Here, when it is determined “yes”, the process proceeds to step s5, and when it is determined “no”, the process proceeds to step s6.

  The initial wobbling amount of the workpiece w can be further added to the above discrimination criterion. In this case, in order to determine whether or not it is necessary to correct the initial shake amount of the work, an allowable maximum value of the work initial shake amount is input to the computer numerical control device as a reference value. For example, when the length L of the portion to be ground is 320 mm, the reference value is set to support rotation at both ends. When it is determined based on the shake amount, the reference value is set to 5 μm, for example.

  As described above, when the initial wobbling amount of the work w is used as a reference, the initial wobbling amount of the work w is measured in advance before supplying the work w to the work supporting member 3, for example, in step s 2. Processing such as input from the operation panel is required.

  When measuring the initial run-out amount associated with the rotation of both ends of the workpiece w, for example, the workpiece w is simply supported so that it can be rotated at a specific position by means of a receiving tool or the like. Rotate around. Then, the maximum stroke among the reciprocating displacement strokes of all the points on the longitudinal direction (specific rotation center line direction) of the portion to be ground in the direction orthogonal to the specific rotation center line is measured by a measuring instrument. However, it is usually sufficient to measure the stroke at the center point of the length of the part to be ground and use this as the initial runout associated with both-end support rotation. Processing without any hindrance is realized.

  The reference value may be the initial shake amount associated with the cantilevered support rotation instead of the initial shake amount associated with the double-end supported rotation. Accompanying this, the initial shake amount value is about ½.

  When measuring the amount of deflection associated with the cantilever rotation of the workpiece w, for example, one end of the grinding target portion of the workpiece w is cantilevered and rotated at a specific position, and the workpiece is rotated at this time. Among the strokes of the reciprocating displacement at all points on the longitudinal direction (rotation center line direction) of the portion to be ground in the direction orthogonal to the center line, the maximum stroke is measured with a measuring instrument, and this is determined as the initial deflection amount. However, it is usually sufficient to measure the stroke of the free end of the grinding location and use this as the initial runout amount associated with the cantilever support rotation. Realized. .

  In step s5, the workpiece is subjected to machining by the concave / convex traverse control. Here, the concave / convex traverse control refers to a control executed by a computer numerical control device so as to process a portion to be ground of the workpiece w so as to have a smaller diameter than a portion other than its both end portions. The center-recess traverse control is not limited as long as the outer peripheral surface, which is a portion to be ground of the workpiece w, can be processed into any center-recessed shape including various shapes as shown in FIG. Above, in order to simplify the information processing and the operation of each part, the portion to be ground is cut into a symmetrical trapezoidal shape as shown in FIG. 4 (a) or as shown in FIG. 4 (b). It is supposed to be cut into a symmetrical chevron. In FIG. 4, (c) shows the part to be ground cut in an arc shape, and (d) to (f) show the part to be ground ground asymmetrically.

  Here, as a representative example, the processing of the workpiece w in the case where the portion to be ground is excised into a trapezoid by means of the concave / convex traverse control will be described. In addition to the grinding wheel 1, the adjusting wheel 2 is shown in FIG. Is moved in the X-axis direction, and the adjustment wheel 2 and the grinding wheel 1 sandwich the work w on the work support member 3. Under this state, the grinding wheel 1 is moved onto the work support member 3. In the process of relative movement along the left and right direction (Z-axis direction) from one end of the workpiece w to be ground toward the center point of the length of the workpiece w, a fine cut is made continuously or stepwise. As a result, a tapered surface b1 shown in FIG. 4 (a) is formed at the portion to be ground of the workpiece w, and the grinding wheel 1 becomes the center point of the length of the workpiece w. This time, The grinding wheel 1 grinds the workpiece w while being retreated slightly in the process of being relatively moved along the left-right direction toward the other end of the portion to be ground. w is formed with a tapered surface b2 shown in FIG. As a result, the portion to be ground of the workpiece w is formed with two tapered surfaces b1 and b2, and is ground by the outer peripheral surface of the grinding wheel 1 located at the center of the length of the portion to be ground, so that the width of the grinding wheel 1 is the same. A straight cylindrical surface b3 having a length is formed, and a portion to be ground is cut into a left-right symmetrical trapezoid when viewed from above.

  After the processing by the above-described center recess traverse control, a straight cutting is performed to grind the workpiece w while moving the grinding wheel 1 linearly in the left-right direction along the rotation center line of the workpiece w. The concave part of the workpiece w formed by the traverse control is removed, and the part to be ground becomes a straight cylindrical surface with a uniform diameter. Hereinafter, the control for performing such straight cutting will be referred to as “straight traverse control”.

  In FIG. 4 (a), the maximum dent depth c1 of the middle concave portion of the workpiece w is determined in consideration of the initial deflection amount and grinding allowance of the workpiece w, and specifically, for example, about 40 μm. This maximum dent depth c1 does not need to be realized by one pass of the grinding wheel 1, and in particular, in order to improve the runout accuracy, a maximum dent depth c1 of 40 μm is obtained by many passes of the grinding wheel 1. It is better to make a fine cut. At this time, the cutting amount for each time is, for example, about 0.01 mm or less.

  The above-mentioned machining by the concave / convex traverse control and the machining by the straight traverse control may be performed once or alternately, and the number of times of machining by each control depends on the deflection accuracy. It can be arbitrarily determined in relation to it.

  FIG. 5 shows an example of the movement trajectory of the grinding wheel 1 with respect to the workpiece w in the processing at step s5. (1) is a straight traverse control by performing the processing (the former processing) m1 by the central concave traverse control once. (2) shows the case where the former process m1 is performed once and the latter process m2 is performed a plurality of times. (3) shows the case where the former process m1 is performed a plurality of times. (4) shows the case where both the former machining m1 and the latter machining m2 are performed a plurality of times, and (5) shows the length of the concave portion of the workpiece w to be ground. The case where the latter process m2 is also performed a plurality of times after the former process m1 is performed a plurality of times so as to increase the depth of the central recess every time the grinding wheel 1 passes is shown.

  The machining m1 performed by the center-concave traverse control and the machining m2 performed by the straight traverse control are normally performed in the coarse grinding process, but are not limited to this. You may go. However, in the case of using the rough grinding or the fine grinding, it is necessary to take into account the remaining grinding allowance and appropriately reduce the depth c1 of the concave portion formed by the processing by the concave / convex traverse control. It is.

  After the rough grinding in which the machining m1 by the middle concave traverse control is completed, the conventional middle grinding and the fine grinding are performed, that is, at this stage, the machining m2 by the straight traverse control is repeated. . Finally, the same spark-out is performed as before.

  On the other hand, in step s6, the machining m1 by the middle concave traverse control is not performed, and the roughing, the middle roughing, and the fine grinding are performed by the processing m2 by the normal straight traverse control, and finally the spark out is executed. The

In step s7, the processing for the workpiece is completed. Here, the rotation of the grinding wheel 1 and the adjustment wheel 2 is stopped, and then the grinding wheel 1 is separated from the adjustment wheel 2 and the workpiece w. Thereafter, the workpiece w is taken out from the workpiece support 3 by manual operation or automatically by a robot.
Thereafter, the same processing is repeated for each workpiece.

  In the above example, the present invention is implemented using the centerless cylindrical grinder 100. However, instead of this, a cylindrical grinder 101 shown in FIG. 6 may be used. In this case, the workpiece w is supported by the spindle hole 10 and the center hole of the center hole piece e1, e1 brazed to both end faces of the workpiece w by the spindle center 10 and the tailstock center 11, and is driven by the driving force of the spindle 10A. It is rotated. Further, the table 7a moved on the bed 7 in the Z-axis direction (left-right direction) is provided with anti-sway means 2A for preventing the deflection of the work w during the processing of the workpiece w, and the processing is executed in this state. Further, as another method using a cylindrical grinder, the support roller 2 that performs a support operation according to the work support member 3 and the adjusting wheel 2 on the table 7a instead of the spindle center 10 and the tailstock center 11 can be rotated. And processing in a state according to the case of the centerless cylindrical grinder 100 is executed. In this case, the support roller 2 applies a rotational force to the workpiece w, and supports the workpiece w by contacting the entire length of the outer peripheral surface of the workpiece w to be ground.

Next, FIG. 7 to FIG. 10 show data when actually grinding with a centerless cylindrical grinder.
The contents will be briefly described below for each figure.

  FIG. 7 shows two small-diameter elongated workpieces (w1) and (w2) having a nominal diameter of 8 mm and a length of a portion to be ground of 320 mm, a grinding wheel 1 having a width of 150 mm, and machining m1 by means of a center concave traverse control. The data is shown when grinding is performed only with the machining m2 by straight traverse control.

  As shown in FIG. 7, in the workpiece of (w1), when the raw material remaining only in the grinding process is ground to 8.05 mm in diameter in the same manner as in the past through the respective steps of coarse grinding, medium roughing, and fine grinding, The runout accompanying the rotation of both ends of the work (w1) was 25 μm. Then, after this, it took many times as long as the conventional method, and the portion to be ground was measured for runout with a diameter of 8.04 mm, runout with a diameter of 8.03 mm, ..., with a diameter of 8.02 mm. When grinding was performed to a diameter of 7.997 mm through a vibration measurement and a vibration measurement at a diameter of 8.0 mm, the vibration associated with the rotation of both ends was 6 μm.

  In the workpiece (w2), when the raw material that has been left with only the grinding process is ground to 8.10 mm in diameter in the same manner as in the prior art after passing through the stages of Roughening, Central Roughening, and Precision, both ends of the workpiece (w2) The shake accompanying the support rotation was 25 μm. Then, after this, it took many times as long as the conventional method, and the portion to be ground was measured for runout at a diameter of 8.07 mm, runout at a diameter of 8.06 mm, ..., at a diameter of 8.03 mm. When grinding was performed to a diameter of 7.997 mm through a vibration measurement and a vibration measurement at a diameter of 8.01 mm, the vibration associated with rotation at both ends was 3 μm.

  The machining data for these workpieces (w1) and (w1) shows that, when the diameter is 8 mm, the amount of deflection associated with the rotation of both ends of the workpieces (w1) and (w1) when the machining is performed over many times the conventional time. When the allowable limit value is set to 5 μm, it can be approached or less than that. That is, it is possible to reduce the amount of run-out associated with both-end support rotation to 5 μm or less by increasing the processing time by making the cutting by the grinding wheel 1 extremely small. Looking at this from the viewpoint of workpiece w rigidity, the workpiece w having a diameter of 8 mm and a length of about 320 mm has such a rigidity that the deflection associated with the rotation can be improved even by processing with a conventional centerless grinder. I can say that.

  FIG. 8 shows the present invention in which two small-diameter elongated workpieces (w3) and (w4) having a nominal diameter of 6 mm and a length of a portion to be ground of 320 mm are alternately subjected to machining m1 by means of a center concave traverse control and machining m2 by means of a straight traverse control. The data when it grinds with the processing method which concerns on is shown.

  In FIG. 8, the upper part shows data when processing is performed using a grinding wheel 1 having a width of 150 mm, and the lower part shows data when processing is performed using a grinding wheel 1 having a width of 50 mm. Yes.

  As shown in the upper part of FIG. 8, for the workpiece (w3), a grinding wheel 1 having a width of 150 mm was used, and the raw material that had been left with only grinding was spent roughly 10 minutes. When grinding to 6.28 mm in diameter after passing through each of the coarse grinding and fine grinding stages, the runout accompanying the rotation at both ends was 104 μm. After this, when the portion to be ground was ground to 5.998 mm after passing through a runout measurement with a diameter of 6.20 mm and a runout measurement with a diameter of 6.15 mm over a period of several minutes to a few dozen minutes, The shake accompanying the rotation of both ends of the workpiece was 50 μm.

  After the machining shown in the upper stage, the grinding wheel 1 of the centerless cylindrical grinding machine 100 is replaced with one having a width of 50 mm, and the machining for the workpiece (w3) is continued. The machining data at this time is shown in FIG. As shown in the bottom row.

  As shown in the lower part of FIG. 8, with respect to the workpiece of (w3), the processing using the grinding wheel 1 having a width of 50 mm took about 15 minutes to make the portion to be ground at a diameter of 5.95 mm. When grinding to a diameter of 5.5 mm through a vibration measurement, a vibration measurement at a diameter of 5.9 mm, ..., a vibration measurement at a diameter of 5.6 mm, and a vibration measurement at a diameter of 5.55 mm, both ends support rotation The accompanying vibration became 3 μm.

  On the other hand, as shown in the upper part of FIG. 8, for the workpiece of (w4), a grinding wheel 1 having a width of 150 mm is used, and it takes roughly 10 minutes to roughen the raw material that has been left with only grinding. When grinding to 6.30 mm in diameter after passing through the respective stages of Nakarakken and Seiken, the runout associated with the rotation of both ends was 20 μm. Here, the deflection of the workpiece (w4) is small because the initial bending of the raw material was small. After that, it takes about several minutes to several tens of minutes, and the portion to be ground is measured for runout at a diameter of 6.25 mm, runout at a diameter of 6.205 mm, ..., at a diameter of 6.10 mm. After grinding to a diameter of 5.998 mm after passing through a runout measurement of 6.04 mm in diameter, the runout accompanying rotation at both ends was 6 μm.

  After the machining shown in the upper stage, the grinding wheel 1 of the centerless cylindrical grinding machine 100 is replaced with one having a width of 50 mm, and the machining of the workpiece (w4) is continued. As shown in

  As shown in the lower part of FIG. 8, with respect to the workpiece of (w4), by using the grinding wheel 1 having a width of 50 mm, it took a time of about several minutes to several tens of minutes, and the portion to be ground was changed to a diameter of 5 When grinding to a diameter of 5.5 mm through a vibration measurement at a diameter of 5.9 mm, a vibration measurement at a diameter of 5.85 mm, a vibration measurement at a diameter of 5.6 mm, and a vibration measurement at a diameter of 5.55 mm. The runout accompanying both-end support rotation was 2.5 μm.

  The machining data of these workpieces (w3) and (w4) shows that when the workpiece w is 6 mm in diameter and about 320 mm in length, when the grinding wheel 1 with a width of 150 mm is machined, the deflection amount of the workpiece w is rapidly improved. Although it is not performed, when the grinding whetstone 1 having a width of 50 mm (a size shorter than 1/3 of the length L of the workpiece w to be ground) is machined, the deflection amount of the workpiece w is relatively short. It shows that it improves rapidly.

  In addition, when the conventional processing only by the straight traverse control is performed on the workpiece w having a diameter of 6 mm and a length of about 320 mm by using a centerless grinding machine or a cylindrical grinding machine, no matter how much time is taken, Experience has confirmed that the amount of deflection of the workpiece w is not less than about 5 μm.

  FIG. 9 shows the machining m1 by controlling the concave / convex traverse by using the grinding wheel 1 having the diameter D of 4.8 mm and the grindstone 1 having the width of 50 mm and the six small-diameter elongated workpieces No1 to No6 having a width of 50 mm. And data when grinding is performed by the machining method according to the present invention in which machining m2 by straight traverse control is alternately performed.

  The amount of run-out associated with both-end support rotation after machining each workpiece No. 1 to No. 6 is within the range of 0.002 mm to 0.006 mm. It is as follows. At this time, the difference in the amount of runout after machining for No. 1 to No. 6 is because the initial runout amount is different and there are subtle differences in each processing condition and material structure. is there.

  The machining time of each workpiece from No. 1 to No. 6 is about 10 minutes. The machining conditions for the work No. 5 are shown in detail in FIG.

  As shown in FIG. 10, in rough grinding, table feed (relative displacement in the Z-axis direction between the grinding wheel 1 and the adjusting wheel 2) with a cutting depth of 0.01 mm is performed 60 times, and the cutting depth of the grinding stone 1 The total is 0.6 mm, and the machining m1 by the concave / concave traverse control is performed every time the table is fed. As a result, the portion to be ground is ground in a concave shape every time the table is fed, and the maximum concave depth c1 of the concave portion in each round is 0.04 mm.

  Next, the table feed is performed 6 times with a cut depth of 0.005 mm, the total cut depth of the grinding wheel 1 is 0.03 mm, and the machining m2 by the straight traverse control is performed every time the table feed is performed. As a result, the portion to be ground of the workpiece can be brought close to a straight cylindrical surface with a uniform diameter, but strictly speaking, the portion to be ground is still in a concave shape with a maximum recess depth c1 of 0.01 mm.

  Next, table feed with a cutting depth of 0.005 mm is performed 8 times, and each time the table feed is performed, the maximum recess depth c1 at the center of the length of the portion to be ground is increased stepwise and gradually approaches 0.04 mm. Processing m1 by such a concave / convex traverse control is performed. As a result, the portion to be ground is ground into a concave shape, and the maximum concave depth c1 of this concave portion is finally 0.04 mm.

  Next, the table feed is performed 22 times with a cut depth of 0.01 mm, and the total cut depth of the grinding wheel 1 is 0.22 mm. Therefore, the processing m1 by the concave / convex traverse control in which the depth c1 is 0.04 mm is performed. During the processing m1 by the center-recess traverse control, the maximum recess depth c1 at the center of the length of the part to be ground is always maintained at 0.04 mm.

  Next, the table feed is performed 6 times with a cut depth of 0.005 mm, so that the total cut depth of the grinding wheel 1 is 0.03 mm, and the machining m2 by the straight traverse control is performed every time the table feed is performed. As a result, although the part to be ground of the workpiece has a shape approximating a straight cylindrical surface with a uniform diameter, strictly speaking, the part to be ground is still indented with a maximum recess depth of 0.01 mm. .

  In the processing up to this point, although the maximum recess depth c1 of the workpiece w is changed to a large or small size, it is always maintained in a concave shape, and both ends of the workpiece w always contact the outer peripheral surface of the adjustment wheel 2 during processing. Therefore, the phenomenon of separation as shown by the dotted line d1 in FIG. 12 due to the bending of the workpiece w at one end of the portion to be ground during processing is prevented, and this is prevented. It is assumed that it is possible to grind w so that the runout accompanying the rotation is sufficiently small.

  Thereafter, the machining of Nakarikuken, Seiken, and Spark Out is carried out by machining with the straight traverse control m2. It should be noted that it is possible to insert the machining m1 by means of the concave / convex traverse control at the intermediate roughing or fine polishing stage. In this case, however, the depth c1 of the portion to be ground and the cutting amount of one table feed Must be reduced accordingly.

  The actual grinding time from the start of rough grinding to the end of spark-out for this No. 5 work was 19 minutes and 30 seconds, and a tremendous improvement in efficiency was realized compared to the conventional required time (1 day). It is.

It is a top view which shows the centerless cylindrical grinder used for implementation of this invention. A part of the centerless cylindrical grinder is shown, in which A is a plan view and B is a side view. It is a flowchart of the operation | work in the case of implementing this invention using the above-mentioned centerless cylindrical grinder. It is the figure which looked at the middle concave part from the upper part which shows the various shape of the middle concave part which can be employ | adopted when making the to-be-ground part of a workpiece | work into a concave shape in implementation of this invention. It is a figure which shows the various movement trajectories of the grinding wheel with respect to a workpiece | work when implementing this invention. It is a top view which shows a part of cylindrical grinder used for implementation of this invention. It is a figure which shows the data when two small diameter elongate workpieces are ground only by the process by straight traverse control. It is a figure which shows the data when two small diameter elongate workpieces are ground by implementation of this invention. It is a figure which shows the data when six small diameter elongate workpieces are ground by implementation of this invention. It is a figure which shows the detailed process conditions about the No. 5 workpiece | work in FIG. It is a top view which shows a mode that the small diameter elongate workpiece | work is plunge-processed with a centerless grinding machine. It is a figure which shows a mode that the traverse process is implemented with the grinding wheel of the width | variety smaller than a workpiece | work length with a centerless grinding machine with a small diameter elongate workpiece.

Explanation of symbols

a2 Width of grinding wheel 1 O1 Rotation center line of grinding wheel 1 O2 Rotation center line of adjusting wheel 2 Workpiece 1 Grinding wheel 2 Support roller (adjusting wheel)
2A Stabilizing means 3 Work support member 10 Spindle center 10A Spindle 11 Tailstock center 100 Centerless cylindrical grinder 101 Cylindrical grinder

Claims (6)

In the process of grinding the outer peripheral surface, which is the part to be ground, of a small diameter elongated workpiece such as a long drill material into a straight cylindrical surface with a uniform diameter, the part excluding both ends of the part to be ground is more than the both ends. A work grinding method for a long drill material or the like, characterized by inserting a step of grinding into a concave shape with a small diameter. 2. A work grinding method for a long drill material or the like according to claim 1, wherein the work grinding method is carried out using a cylindrical grinder provided with a grinding wheel, a spindle, a spindle center, and a tailstock center and provided with a steadying means. A support roller and a grinding wheel are provided so as to be rotatable around a parallel center line, to be relatively displaceable in the direction of the center line, and to be relatively displaceable in a direction crossing the center line direction. In a specific clamping state in which the outer peripheral surface, which is a portion to be ground of a small-diameter elongated workpiece such as a long drill material, is sandwiched at a specific position, the portion to be ground is ground into a concave shape, A work grinding method for a long drill material or the like, wherein the grinding wheel is moved in a straight line in the center line direction in the specific clamping state to grind the outer peripheral surface to be ground. The work grinding method for a long drill material or the like according to claim 2 or 3, wherein the grinding wheel has a width of 1/3 or less of the work length. 5. A work grinding method for a long drill material or the like according to claim 1, wherein the work grinding method is carried out using a centerless cylindrical grinder provided with an adjusting wheel, a grinding wheel and a work supporting member. The first step of grinding the portion to be ground in a concave shape and the second step of grinding the portion to be ground into a right cylindrical surface shape are performed so as to be repeated an arbitrary number of times in this order. 2. A work grinding method for a long drill material according to 2, 3, 4 or 5.

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