JP2009113161A - Grinding method and grinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding method for easily and precisely grinding and machining a peripheral surface of a workpiece having a straight surface and tapered surfaces formed on both sides of the straight surface, as the peripheral surface. <P>SOLUTION: The grinding method is composed of: a first grinding step in which the straight surface 2 and the first tapered surface 3a of the workpiece 1 are ground to desired diameters, respectively, and the second tapered surface 3b is ground to a predetermined diameter that is smaller than a desired diameter; a measuring step in which locations at which machined diameters of the first tapered surface 3a and the second tapered surface 3b conform to respective preset dimensions, are obtained by moving a machined diameter measuring device 14, and an interval between the two locations is measured; a calculating step in which a dimension of the straight surface 2 in an axial direction is calculated, and a difference between a result of the calculated dimension and a desired value is obtained; and a second grinding step in which the second tapered surface 3b is ground so as to eliminate the difference. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for grinding an inner peripheral surface or an outer peripheral surface of a workpiece.

2. Description of the Related Art Conventionally, there has been known an internal grinding machine that grinds an inner peripheral surface of a workpiece by cutting and feeding the grinding wheel and the workpiece while rotationally driving a grinding wheel shaft provided with a grinding wheel at a tip portion. Recently, in order to grind the inner peripheral surface with higher accuracy, a processing diameter measuring means capable of detecting the processing diameter of the work inner peripheral surface is mounted during the work processing, and based on the processing diameter measured by the measuring means. An internal grinder that controls the cutting feed amount has also been proposed (Patent Document 1).
JP 2003-275957 A

  In the internal grinding machine, there is a case where a workpiece having a straight surface along the axis as an inner peripheral surface and tapered surfaces arranged on both sides in the axial direction is processed. For example, a die (die) for drawing a shaft-shaped part is an example. In this type of work, the accuracy of this surface is required because the inner diameter dimension of the straight surface and the dimension in the axial direction influence the accuracy of the molded product (product). Therefore, in the grinding process, the process proceeds while measuring each dimension of the straight surface as necessary.

  At that time, the processing diameter of the straight surface is relatively easy to measure, and the processing diameter can be directly measured by a grinding machine such as in Patent Document 1. However, the axial dimension of the straight surface is difficult to measure accurately with the workpiece fixed to the main shaft because both sides of the straight surface are tapered surfaces as described above. For this reason, it is unavoidable to measure the workpiece after removing it from the main spindle, and then re-fixing the workpiece to the main spindle to perform centering and then machining. In this way, even with a method of attaching / detaching a workpiece to / from the spindle during processing, if the dimensional accuracy required in the past is used, it is possible to cope by correcting the misalignment due to attachment / detachment. However, in recent years, the number of workpieces that require higher machining accuracy has increased, and with conventional machining methods, there is a limit to the accuracy of misalignment correction, and due to misalignment, the length of the straight surface is made uniform on the workpiece circumferential surface. Therefore, it is difficult to satisfy the required processing accuracy.

  The present invention has been made in view of the above circumstances, and as a peripheral surface, such as a die (die) for drawing a shaft-shaped part, a straight surface and tapered surfaces arranged on both sides in the axial direction thereof, It is an object of the present invention to make it possible to more easily and accurately grind a workpiece having a gap.

  The applicant of the present application paid attention to a grinding apparatus equipped with a processing diameter measuring means capable of measuring the processing diameter of the inner peripheral surface of the workpiece as in Patent Document 1. And while moving the processing diameter measuring means in the axial direction of the workpiece, each position on the axis where the processing diameter becomes a predetermined diameter on each tapered surface is detected, and the interval between these positions is determined as the processing diameter measuring means From the distance and the known value of the workpiece, the idea of deriving the length of the straight surface of the workpiece in the axial direction was invented, and the following grinding method was invented.

  That is, in the grinding method according to the present invention, the first taper having an inclination of a predetermined angle with respect to the axial line is arranged on both sides of the straight surface in the axial direction and the straight surface along the axial line as the inner peripheral surface or the outer peripheral surface. A method of grinding each surface of a workpiece having a surface and a second tapered surface, wherein the grinding wheel and the workpiece are rotated while the workpiece fixed to the main shaft and the grinding wheel fixed to the grinding wheel shaft are rotationally driven. A first grinding step of grinding the first tapered surface and the straight surface to a target diameter and grinding the second tapered surface to a predetermined diameter less than the target diameter by relatively feeding each of the surfaces in the cutting direction; The first taper surface and the second taper are measured by measuring the work diameter of the work peripheral surface while moving the work diameter measuring means movable relative to the work fixed to the spindle in the axial direction of the work. A measuring step of detecting the positions in the axial direction in which the machining diameter of the machining diameter becomes a preset diameter, and measuring an interval between these positions based on a moving amount of the machining diameter measuring means, and the interval and each taper An axial length of the straight surface is calculated based on the angle of the surface, and further, a calculation step for determining a difference between the length and the target value, and the grinding wheel and the second tapered surface of the workpiece in the cutting direction. And a second grinding step of grinding the second tapered surface so as to eliminate the difference.

  According to this method, while moving the machining diameter measuring means in the axial direction of the workpiece, each position on the axis where the machining diameter becomes a predetermined diameter on each tapered surface is detected, and the interval between these positions is determined. Measured based on the movement amount of the machining diameter measuring means, and the axial length of the straight surface of the workpiece is obtained based on the value and the angle of each tapered surface, which is a known value, so the workpiece remains fixed to the main shaft. In this state, a certainly reliable value can be acquired as the axial length of the straight surface. Therefore, it is possible to proceed the grinding operation without removing the workpiece from the main shaft in the middle of the workpiece grinding operation as in the prior art, thereby improving the machining accuracy of the workpiece.

  In this method, the amount of grinding in the radial direction of the second tapered surface when the second tapered surface is ground so that the difference is eliminated is based on the difference and the angle of the second tapered surface. In the second grinding step, the machining diameter of the second taper surface is measured by the machining diameter measuring means so that the second taper surface is displaced in the radial direction by the grinding amount. However, it is preferable to grind the second tapered surface.

  Thus, according to the method of grinding the second taper surface while measuring the machining diameter of the second taper surface by the machining diameter measuring means, the second taper surface can be accurately ground. It is possible to finish the axial length to the target value with higher accuracy.

  The machining diameter is measured by bringing each contact piece into contact with the work peripheral surface using the machining diameter measuring means provided with a pair of contact pieces that can be displaced in the radial direction of the work and have spherical contact portions. In this case, in the calculation step, the axial line of the straight surface is corrected after correcting the measurement error of the machining diameter due to the shift in the axial direction between the contact position of the contact portion with respect to each tapered surface and the center of the contact portion. It is preferable to obtain the direction length.

  According to this method, since the axial length of the straight surface of the workpiece can be obtained more accurately, the machining accuracy of the workpiece is further improved.

  In addition, since the amount of deviation in the axial direction between the contact position of the contact portion with respect to the tapered surface and the center of the contact portion depends on the spherical shape forming the contact portion, that is, the diameter size, correction of the measurement error of the processing diameter is as follows. This is done based on this diameter. In this case, the correction may be performed with the diameter dimension as a fixed value. However, since the shape of the contact portion changes with time due to wear, the method with the diameter dimension as a fixed value is not sufficiently reliable. Such a problem is solved by the following method. That is, for example, prior to the execution of the first grinding step, the master work having the straight surface and each tapered surface, and the dimension of the straight surface in the axial direction and the gradient of each tapered surface are known values. The machining diameter of the first taper surface and the second taper surface is set in advance by measuring the peripheral surface of the master workpiece while moving the machining diameter measuring means in the axial direction of the master workpiece while being fixed to the main shaft. The positions in the axial direction are detected and the intervals are measured based on the movement amount of the machining diameter measuring means, and the spherical surface forming the contact portion is formed based on the distance and the known value of the master work. A diameter dimension is obtained, and the measurement error is corrected based on the diameter dimension in the calculation step.

  According to this method, the measurement error of the machining diameter can be corrected based on a value (diameter dimension) closer to the actual shape of the contact portion, so that the reliability of the correction is improved. As a result, the axis of the straight surface of the workpiece It becomes possible to obtain the direction length more accurately.

  Note that the wear of the contact portion does not necessarily occur evenly over the entire contact portion, and a distorted wear state may be considered. Therefore, in the above method, each diameter dimension when the contact portion is in contact with each of the straight surface and each tapered surface as the diameter size of the spherical surface forming the contact portion is individually determined, and in the calculation step, It is preferable to correct the measurement error based on these diameters.

  In this way, according to the method of correcting the measurement error of the machining diameter based on the diameter of the contact portion obtained individually corresponding to each surface of the workpiece, the diameter of the contact portion is assumed on the assumption that the whole wears out evenly. Compared with the above-described method for obtaining the dimensions, the reliability of the correction is further improved.

  On the other hand, the grinding apparatus according to the present invention includes a first taper surface that is arranged on both sides of the straight surface along the axis and in the axial direction as an inner peripheral surface or an outer peripheral surface and has a gradient of a predetermined angle with respect to the axis. And a grinding wheel, a grinding wheel driving means for rotationally driving the grinding wheel shaft, a workpiece supporting means for supporting the workpiece, and a workpiece support. A workpiece driving means for rotationally driving a workpiece supported by the means; a first moving means for relatively moving the grinding wheel and the workpiece supporting means; and a machining diameter measuring means for measuring a machining diameter of the workpiece being ground. And a second moving means for relatively moving the work supported by the work supporting means and the machining diameter measuring means in the axial direction of the work, and a relative movement amount in the axial direction between the work and the machining diameter measuring means. An axial length measuring means for measuring the dimension of the workpiece in the axial direction, an arithmetic means for performing a predetermined calculation based on a measurement result by each measuring means, and a control means for controlling the driving means and each moving means. The control means is configured to grind the first tapered surface and the straight surface to a target diameter and to set the second tapered surface to a target diameter by relatively feeding the grinding wheel and the peripheral surface of the workpiece in a cutting direction. After grinding to a predetermined diameter less than the predetermined diameter, the machining diameter measuring means is moved relative to the workpiece in the axial direction to measure the machining diameter of the workpiece circumferential surface, thereby machining the first tapered surface and the second tapered surface. It is configured to detect the position in the axial direction in which the diameter becomes a preset diameter, and to measure these intervals by the axial length measuring means, and the computing means The axial length of the straight surface is obtained based on the measurement result by the linear length measuring means and the angle of each tapered surface, and the difference between the length and the target value is obtained, and the control means further includes the difference. The grinding wheel and the second taper surface of the workpiece are relatively fed in the cutting direction so as to grind the second taper surface so as to be eliminated.

  According to this grinding apparatus, it becomes possible to automate the grinding operation of the workpiece based on the grinding method according to claim 1, and it is possible to easily and accurately perform the grinding operation of the workpiece having a straight surface and a tapered surface. It becomes.

  In this grinding apparatus, the calculating means calculates the amount of grinding in the radial direction of the second tapered surface when the second tapered surface is ground so as to eliminate the difference, and the difference between the difference and the second tapered surface. And the control means measures the machining diameter of the second tapered surface by the machining diameter measuring means so that the second taper surface is displaced in the radial direction by the grinding amount. However, it may be configured to relatively feed the grinding wheel and the second tapered surface of the workpiece in the cutting direction.

  According to this configuration, the workpiece grinding operation based on the grinding method according to claim 2 can be automated.

  The machining diameter measuring means includes a pair of contact pieces that are displaceable in the radial direction of the workpiece and have spherical contact portions, and measures the machining diameter by bringing each contact piece into contact with the workpiece circumferential surface. The arithmetic means corrects a measurement error of a machining diameter associated with a deviation in the axial direction between the contact position of the contact portion with respect to the tapered surface and the center of the contact portion, and then the axial direction of the straight surface It may be configured to determine the length.

  According to this configuration, it is possible to automate the workpiece grinding operation based on the grinding method according to the third aspect.

  According to the present invention, when grinding a workpiece having a straight surface and tapered surfaces provided on both sides in the axial direction as a peripheral surface, such as a die (die) for drawing a shaft-shaped part, the workpiece straight Grinding can be carried out by accurately obtaining the axial length of the surface without removing the workpiece from the spindle. Accordingly, the workpiece can be ground more easily and accurately than the conventional grinding method (apparatus) in which the workpiece is detached during the processing for measuring the straight surface.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a plan view schematically showing an internal grinding machine to which the present invention is applied. The internal grinding machine shown in this figure includes a work support head 10 for supporting the work 1 and a wheel head 20 having a grinding wheel 24 on its base.

  The workpiece support head 10 is provided with a spindle 12 having a chuck for holding (fixing) the workpiece 1. The main shaft 12 is connected to a driving mechanism (not shown) having a motor as a driving source (corresponding to the work driving means according to the present invention), and is configured to rotationally drive the work 1 held by the chuck. .

  The workpiece support head 10 is further provided with a machining diameter measuring device 14 (hereinafter abbreviated as a measuring device 14; corresponding to the machining diameter measuring means according to the present invention) for measuring the machining diameter (inner diameter) of the workpiece 1. ing. As shown in FIG. 3A, the measuring device 14 has a pair of upper and lower contact pieces 15 applied to the inner peripheral surface of the workpiece 1, and a signal corresponding to the workpiece machining diameter based on the displacement amount of these contact pieces. Is output to the NC device 30 described later. Each contact piece 15 is configured to be displaceable along a vertical axis passing through the main shaft 12 (work center).

  The measuring device 14 is connected to a feed screw mechanism (corresponding to the second moving means according to the present invention) using a motor 16 as a drive source, and the spindle 12 (work 1) is operated by the operation of the feed screw mechanism. It can move in the axial direction. The motor 16 incorporates a rotary encoder, for example, and is configured to output a signal corresponding to the drive of the motor 16, that is, a signal corresponding to the movement amount of the measuring device 14 to the NC device 30 described later.

  The work support head 10 is connected to a turning mechanism (not shown) using a motor as a drive source, and is centered on a position (referred to as a reference position; see FIG. 1) in which the axial direction of the main shaft 12 is parallel to the grindstone shaft 22 described later. As shown in FIG. 2, it is configured to be capable of turning within a certain angle around the vertical axis.

  The wheel head 20 is disposed so as to face the workpiece support head 10 disposed at the reference position in the axial direction of the main shaft 12.

  A wheel head 22 is attached to the wheel head 20, and for example, a flat grinding wheel 24 having a straight grinding wheel surface along the axial direction is fixed to the tip of the wheel head 22. The wheel head 20 incorporates a drive motor (corresponding to the grindstone driving means according to the present invention), and the grindstone shaft 22 and the grindstone wheel 24 are integrally rotated at a high speed by the operation of the motor. It is configured.

  The wheel head 20 is provided so as to be movable in a direction parallel to the grindstone shaft 22 and a direction orthogonal to the horizontal axis (that is, a cutting direction (vertical direction in FIG. 1)). Specifically, on the base, a moving mechanism having a first table 26 movable in a direction parallel to the grindstone shaft 22 and a second table 27 provided on the first table and movable in the cutting direction. The wheel head 20 is supported on the second table 27. That is, in the rotational drive state of the grinding wheel shaft 22 and the grinding wheel 24, the grinding wheel 24 is inserted inside the workpiece 1 and the workpiece support head 10 is fed in the cutting direction as the wheel head 20 is moved by the moving mechanism. By doing so, the grindstone surface of the grinding wheel 24 is pressed against the inner peripheral surface of the workpiece, and the inner peripheral surface is ground.

Here, as shown in FIG. 4, the workpiece 1 is arranged on both sides of the straight surface 2 along the axial line and the straight surface 2 in the axial direction as an inner peripheral surface, and at a predetermined angle (θ ₁ , θ ₂ ), and a workpiece having a first tapered surface 3a and a second tapered surface 3b, such as a die (die) for drawing a shaft-shaped part. Accordingly, in grinding each of the surfaces 2, 3a, 3b, as shown in FIGS. 1 and 2, the work support head 10 is driven to rotate, and the surfaces to be ground (surfaces 2, 3a, 3b) sequentially move in the feed direction. In this state, the wheel head 20 is cut and fed. That is, in this embodiment, the turning mechanism of the work support head 10 and the moving mechanism of the wheel head 20 correspond to the first moving means according to the present invention.

The inclination angle θ _{2 with} respect to the axis of the second taper surface 3b of the workpiece 1 is formed larger than the same inclination angle θ ₁ of the first taper surface 3a, and the accuracy of the angles θ ₁ and θ ₂ is ensured. Yes.

  The above internal grinding machine has an NC device 30 (corresponding to a control means), and the workpiece support head 10, the wheel head 20 and the like execute a predetermined grinding operation according to a program stored in advance. In addition, the NC device 30 is configured to be controlled in an integrated manner.

  The NC device 30 includes, as its functional configuration, a position detection unit that detects the position of the measurement device 14 and various calculation units, and converts the signal output from the encoder of the feed screw mechanism to convert the measurement device 14. The position is detected, the axial dimension of a specific portion of the workpiece 1 is obtained based on the detection result, and the control value for controlling the cutting feed operation of the workpiece support head 10 is calculated. That is, in this embodiment, the encoder and the NC device 30 correspond to the axial direction length measuring means according to the present invention.

  Next, the grinding operation of the internal grinding machine based on the control of the NC device 30 will be described with reference to FIGS.

  The grinding of the inner peripheral surface of the workpiece 1 is performed along the following steps.

[First grinding process]
First, the wheel head 20 is moved by the operation of the moving mechanism and the work support head 10 is moved by the operation of the turning mechanism, whereby the grinding wheel 24 is located at a position having a predetermined gap between the inner peripheral surface and the grinding wheel 24. While being inserted into the workpiece 1, the grindstone surface is arranged so as to face the first preset surface to be processed among the surfaces 2, 3 a, 3 b of the workpiece 1. In this state, the grindstone shaft 22 and the grinding wheel 24 is integrally rotated, and the main shaft 12 and the workpiece 1 are integrally rotated.

  Next, the wheel head 20 is cut and fed by the operation of the moving mechanism. As a result, the grinding wheel 24 is pressed against the first workpiece surface of the workpiece 1 and grinding of the workpiece surface is started.

  When the grinding of the first workpiece surface is completed, the wheel head 20 moves in the direction opposite to the cutting direction, and the grinding wheel 24 is pulled away from the workpiece surface. Then, after the workpiece support head 10 and the wheel head 20 move and the grinding wheel 24 is disposed so that the grinding wheel surface faces the next workpiece surface, the wheel head 20 is cut and fed. Thereby, grinding of the next to-be-processed surface is started.

  In this way, each surface 2, 3a, 3b of the workpiece 1 is ground in a preset order, and when the grinding of the last processed surface is finished, the wheel head 20 moves and a predetermined gap is formed between the workpiece inner peripheral surface. A grinding wheel 24 is arranged at the position.

  Here, in this first grinding step, among the surfaces 2, 3a, 3b of the work 1, the first taper surface 3a having a small angle with the straight surface 2 is set so that each surface 2, 3a has a target machining diameter. The cutting feed amount of the support head 10 is controlled by the NC device 30. For example, during machining, the contact piece 15 of the measuring device 14 is inserted into the workpiece 1 by the operation of the feed screw mechanism to measure the machining diameter, and the cutting feed amount of the wheel head 20 is determined based on the measured value. Be controlled. Thereby, the straight surface 2 and the 1st taper surface 3a are processed by the target processing diameter. On the other hand, the second tapered surface 3b of the workpiece 1 is machined to a predetermined diameter that is less than the target machining diameter. That is, the second tapered surface 3b is undersized.

  As shown in FIG. 3B, during the processing, the entire grinding wheel 24 is biased in the cutting feed direction (left side in the figure) with respect to the center of the workpiece 1. Each contact piece 15 and the grinding wheel 24 do not cause interference.

[Measurement process]
Next, the measuring device 14 is moved by the operation of the feed screw mechanism, and the machining diameter of the work inner peripheral surface is scanned in the axial direction as shown in FIG. As a result, the machining diameter of the first taper surface 3a and the second taper surface 3b is set in advance as a preset dimension D ₁ (a value obtained by adding a predetermined value 2α to the target machining diameter D ₀ of the straight surface 2). detected a predetermined position P1, P2, respectively, the interval _{L 2} in the axial direction of these positions P1, P2 are determined.

[Calculation process]
Next, the axial length L _{1 of the} straight surface 2 based on the interval L ₂ value obtained in the measurement process and the known values (angles θ ₁ , θ ₂ ) regarding the shape of the work inner peripheral surface by the NC device 30. together (referred straight dimension L ₁₎ is calculated, the difference ΔL of the straight dimension L ₁ and the target value L ₀ is determined and further when the difference ΔL is grinding the second tapered surface 3b so as to eliminate The grinding amount ΔD in the radial direction of the second tapered surface 3b is calculated.

  These calculations are performed based on the following formula, for example.

<Equation 1>: L ₁ = L ₂ −α (1 / tan θ ₁ + 1 / tan θ ₂ )
<Equation 2>: ΔL = L ₁ −L ₀
<Number _{3>: ΔD = ΔLtanθ 2 =} (L 1 -L 0) tanθ 2
That is, as shown in FIG. 5, distance _{L 2} of the positions P1, P2 is
L ₂ = L ₁ + L _a + L _b
It is. Here, L _a and L _b are axial lengths from the positions P1 and P2 to the end of the straight surface 2,
L _a = α / tan θ ₁ , L _b = α / tan θ ₂
Therefore, the straight dimension L _{1 to be obtained} is as shown in the above equation 1 from the formulas of L ₂ , L _a , and L _b . Further, at the time of calculation process, since the second tapered surface 3b of the workpiece 1 is a step of undersize processing, the relationship between the straight dimension L ₁ and the target value L ₀ and these differences ΔL is shown in FIG. 6 Therefore, the amount of grinding ΔD in the radial direction of the second tapered surface 3b when the second tapered surface 3b is ground so that the difference ΔL is eliminated is expressed by the above Equation 3.

[Second grinding process]
The wheel head 20 and the work support head 10 move, and the grinding wheel 24 is disposed so that the grinding wheel surface faces the second tapered surface 3b, and the measuring device can measure the processing diameter of the second tapered surface 3b. 14 is arranged. In this state, the wheel head 20 is cut and fed to the second tapered surface 3b, whereby the grinding of the second tapered surface 3b is started.

  During machining, the machining diameter of the second tapered surface 3b is continuously measured by the measuring device 14. When the machining diameter (radius) changes by the grinding amount ΔD while monitoring the measurement value of the measurement device 14, the NC device 30 stops the cutting feed and moves the workpiece support head 10 in the reverse direction.

In this way, the second tapered surface 3b is ground so that the machining diameter changes by the grinding amount ΔD, so that the straight surface 2 is cut in the axial direction by the difference ΔL. As a result, the straight dimension of the straight surface 2 is reduced. It is finished to the target value _{L 0.}

According to the grinding method and apparatus described above, as described above, seeking straight dimension L ₁ of the straight surface 2 without detaching the workpiece 1 from the spindle 12 can be advanced grinding operations. Therefore, unlike the conventional method in which the workpiece is once removed from the spindle and the straight surface is measured, there is no room for misalignment due to attachment and detachment, and correction of misalignment is not required. It becomes possible to carry out with high accuracy. Moreover, the value of the straight dimension L ₁ of the straight surface 2 is required, the axial distance L ₂ between the predetermined actually measured based on the amount of movement of the measuring device 14 while measuring the machining diameter of the workpiece circumferential surface positions P1, P2 Since it is determined based on the known value of the workpiece 1, its reliability is high. Therefore, the workpiece 1 such as the above die (die) having the straight surface 2 having a severe dimensional tolerance can be processed without difficulty. It becomes possible.

In addition, said embodiment is an illustration in case the tip shape of the contact piece 15 (namely, the shape of the contact part which concerns on this invention) is not considered about the measuring apparatus 14, and is calculated | required by considering a tip shape. The reliability of the straight length of the surface 2 can be further increased. That is, the tip of the contact piece 15 is usually spherical in order to suppress wear. Therefore, in the measurement process, as shown in FIG. 7, the contact position of the contact piece 15 in the axial direction of the workpiece 1 is shown. And a difference Δl occurs between the center of the contact piece 15 and a measurement error occurs in the machining diameter in relation to the position of the measuring device 14. Since this deviation Δl is a minute value, it can be ignored depending on the required machining accuracy of the workpiece 1. However, in the second embodiment below, the measurement error of the machining diameter associated with this deviation Δl is corrected. in explaining an example of obtaining a straight dimension L ₁ of the straight surface 2.

<Second Embodiment>
In the second embodiment, in the calculation step, straight dimension L ₁ of the straight surface 2 is calculated based on the following equation.

<Equation 4>
L ₁ = L ₂ − {1 / tan θ ₁ (α−r ₀ + r ₁ / cos θ ₁ ) + 1 / tan θ ₂ (α−r ₀ + r ₂ / cos θ ₂ )}
That is, as shown in FIG. 8, the interval _{L 2} of the positions P1, P2 is
L ₂ = L ₁ + L _a + L _b
It is. Here, when the contact piece 15 is in contact with the straight surface 2 and the tapered surfaces 3a and 3b, the tip shape of the contact piece 15 is distinguished and the diameter (radius) thereof is set to r ₀ , r ₁ , r ₂ , respectively. And the amount of radial displacement per contact piece 15 when the contact position of the contact piece 15 is moved from the straight surface 2 to the tapered surfaces 3a, 3b is α,
L _a = 1 / tan θ ₁ (α−r ₀ + r ₁ / cos θ ₁ )
L _b = 1 / tan θ ₂ (α−r ₀ + r ₂ / cos θ ₂ )
It becomes. Therefore, it is possible to obtain the number 4 from these equations and the distance L ₂ Prefecture.

In short, the measured machining diameter is the machining diameter at the contact position where the contact piece 15 contacts the tapered surfaces 3a, 3b, and not the machining diameter at the center of the contact piece 15 (original measurement positions P1, P2). In the embodiment, the measured machining diameter is corrected based on the tip shape (radius r ₀ , r ₁ , r ₂ ) of the contact piece 15, that is, corrected to the value measured at the center of the contact piece 15, and then the straight surface 2. so that the determination of the straight dimension L _1.

The tip shape (radius r ₀ , r ₁ , r ₂ ) of the contact piece 15 is an unknown value that varies according to the wear of the contact piece 15, and these values are approximate values using a master work in advance. Get as.

Specifically, a master work whose straight dimension L ₁ and angles θ ₁ , θ ₂ are known is fixed to the main shaft 12, and the distance L ₂ is based on the master work diameter measured at three different points in the axial direction. the calculated respectively (determined 3 times the interval L ₂ by changing the displacement amount alpha), obtains the radius r _0, r _1, r ₂ from the result, previously pre-is stored in the NC device 30 this value.

According to the grinding method and apparatus of the second embodiment as described above, as described above, the machining diameter associated with the deviation Δl between the contact position of the contact piece 15 and the center of the contact piece 15 (main body measurement positions P1, P2). since the measurement error on corrected seek straight dimension L ₁ of the straight surface 2, the reliability of the straight dimension L ₁ which is obtained by computation process is improved. Therefore, the workpiece 1 can be machined with higher accuracy.

In particular, the tip shape of the contact piece 15, determined individually depending on the contact state of the workpiece 1 each surface 2, 3a, to 3b, the straight distance L using the value (radius _{r 0, r 1, r 2} ) since so as to obtain a _1, is characterized in that the straight dimension L ₁ obtained become more reliable value. That is, it is considered that the tip shape of the contact piece 15 is slightly different for each contact position with respect to each surface 2, 3a, 3b depending on the degree of wear. According to the method of approximating the tip shape (radius r ₀ , r ₁ , r ₂ ) of the contact piece 15 by distinguishing for each contact state, such a subtle difference for each contact point can be taken into account, and thus it is required. reliability of the straight dimension L ₁ becomes more higher.

In the case of the second embodiment, it is desirable to update the value of the tip shape (radius r ₀ , r ₁ , r ₂ ) of the contact piece 15 every fixed cycle, for example, every time a predetermined number of workpieces 1 are processed. . That is, the tip shape of the contact piece 15 in order to change over time due to wear, in order to ensure the reliability of the straight dimension L ₁ is at a constant cycle, the tip shape (radius r ₀ of the contact piece 15 with a master work , R ₁ , r ₂ ), and it is preferable to update the values.

  By the way, the grinding method and the internal grinding machine described above are examples of a preferred embodiment of the present invention, and the specific method and configuration can be appropriately changed without departing from the gist of the present invention. is there.

  For example, in the grinding method and apparatus of the embodiment, the grinding amount ΔD in the radial direction of the second taper surface 3b when the second taper surface 3b is ground so as to eliminate the difference ΔL is obtained, and the second grinding step The second taper surface 3b is ground while measuring the machining diameter by the measuring device 14 so that the second taper surface 3b is displaced in the radial direction by the grinding amount ΔD. It is also possible to calculate the cutting feed amount of the wheel head 20 when the second tapered surface 3b is ground so as to eliminate this, and to control the wheel head 20 according to the value.

  Further, in the first and second grinding steps of the embodiment, the cutting feed is performed by automatic control of the wheel head 20 by the NC device 30, but of course, it may be performed manually. For example, in the second grinding step, the grinding amount ΔD may be subtracted and displayed on a display means such as a CRT with the cutting feed, and the operator may manually cut and feed the wheel head 20 while referring to the display. .

Further, in the calculation process of the second embodiment, the value (radius value) of the tip shape of the contact piece 15 is a value (radius r ₀ , r) corresponding to the contact state with each surface 2, 3 a, 3 b of the workpiece 1. ₁ , r ₂ ) is used to correct the measurement error of the machining diameter, but, of course, a common value may be used regardless of the contact state with each surface 2, 3a, 3b of the workpiece 1. . In the implementation, the value (radius value) of the tip shape of the contact piece 15 is obtained using the master work, but a predetermined fixed value may be used.

It is a top view (planar schematic diagram) which shows the outline of the internal grinding machine (internal grinding apparatus) which concerns on the 1st Embodiment of this invention. It is a top view of an internal grinding machine (internal grinding machine) showing an example of an operation state of a work support head. It is a schematic diagram which shows the structure of a processing diameter measuring apparatus ((a) is a longitudinal cross-sectional view, (b) is the sectional view on the AA line of (a)). It is sectional drawing which shows the shape of a workpiece | work. It is the schematic explaining the grinding method of a workpiece | work. It is the schematic explaining the grinding method of a workpiece | work. It is a figure explaining the subject when the tip shape of the contact piece of a processing diameter measuring device is spherical (spherical). It is a figure explaining the internal grinding machine (grinding method) which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Work 2 Straight surface 3a, 3b Tapered surface 10 Work support head 12 Spindle 14 Processing diameter measuring device 20 Wheel head 22 Grinding wheel shaft 24 Grinding wheel 30 NC device

Claims (8)

As an inner peripheral surface or an outer peripheral surface, a straight surface along the axis and a first taper surface and a second taper surface that are arranged on both sides of the straight surface in the axial direction and have a gradient of a predetermined angle with respect to the axis. A grinding method for each surface of the workpiece,
By rotating and driving the workpiece fixed to the main shaft and the grinding wheel fixed to the grinding wheel shaft, the grinding wheel and the surfaces of the workpiece are relatively fed in the cutting direction, whereby the first tapered surface and the straight surface A first grinding step of grinding the second tapered surface to a predetermined diameter that is less than the target diameter,
The machining diameters of the first taper surface and the second taper surface are measured by measuring the machining diameter of the workpiece peripheral surface while moving the machining diameter measuring means that can move relative to the workpiece fixed to the spindle in the axial direction of the workpiece. A measuring step of detecting the positions in the axial direction in which the diameter is set in advance and measuring the distance between these positions based on the amount of movement of the processing diameter measuring means;
A calculation step for obtaining an axial length of the straight surface based on the interval and the angle of each tapered surface, and further obtaining a difference between the length and its target value;
A second grinding step of relatively feeding the grinding wheel and the second tapered surface of the workpiece in a cutting direction and grinding the second tapered surface so as to eliminate the difference;
A grinding method comprising: The grinding method according to claim 1,
A grinding amount in the radial direction of the second tapered surface when the second tapered surface is ground so as to eliminate the difference is obtained in the calculation step in advance based on the difference and the angle of the second tapered surface. In the second grinding step, the second tapered surface is measured while measuring the machining diameter of the second tapered surface by the machining diameter measuring means so that the second tapered surface is displaced in the radial direction by the grinding amount. Grinding method characterized by grinding. In the grinding method according to claim 1 or 2,
Using the machining diameter measuring means provided with a pair of contact pieces that can be displaced in the radial direction of the workpiece and having a spherical contact portion, the machining diameter is measured by bringing each contact piece into contact with the work peripheral surface, In the calculation step, the axial length of the straight surface is obtained after correcting a measurement error of a machining diameter associated with a deviation in the axial direction between the contact position of the contact portion and the center of the contact portion with respect to each tapered surface. A grinding method characterized by the above. In the grinding method according to claim 3,
Prior to performing the first grinding step, a master work having the straight surface and each tapered surface and having a known dimension in the axial direction of the straight surface and a gradient of each tapered surface is fixed to the main shaft. Then, by measuring the peripheral surface of the master workpiece while moving the machining diameter measuring means in the axial direction of the master workpiece, the machining axis of the first taper surface and the second taper surface becomes a preset diameter. The position of each direction is detected and these intervals are measured based on the movement amount of the machining diameter measuring means, and the diameter of the spherical surface forming the contact portion is determined based on the distance and the known value of the master work. The grinding method is characterized in that, in the calculation step, the measurement error is corrected based on the diameter. In the grinding method according to claim 4,
As the diameter of the spherical surface forming the contact portion, each diameter size when the contact portion is in contact with the straight surface and each taper surface is obtained separately, and the calculation step is based on these diameter sizes. A grinding method, wherein the measurement error is corrected. Workpiece provided with a first taper surface and a second taper surface that are arranged on both sides of the straight surface in the axial direction and a straight surface along the axis as the inner peripheral surface or outer peripheral surface and have a gradient of a predetermined angle with respect to the axis A device for grinding each of the surfaces,
Grinding wheel, grinding wheel driving means for rotationally driving the grinding wheel shaft, work supporting means for supporting the work, work driving means for rotationally driving the work supported by the work supporting means, the grinding wheel and the work supporting means A first moving means for moving the workpiece relative to each other, a machining diameter measuring means for measuring a machining diameter of the workpiece being ground, a workpiece supported by the workpiece support means, and the machining diameter measuring means. A second moving means for relative movement in the direction, an axial length measuring means for measuring the dimension of the workpiece in the axial direction based on the amount of relative movement between the workpiece and the machining diameter measuring means, and a measurement result by each measuring means Calculation means for performing a predetermined calculation on the basis of, and a control means for controlling the drive means and each moving means,
This control means grinds the first tapered surface and the straight surface to the target diameter by relatively feeding the grinding wheel and the peripheral surface of the workpiece in the cutting direction, and the second tapered surface is less than the target diameter. After grinding to a predetermined diameter, the machining diameter of the first taper surface and the second taper surface is determined by moving the machining diameter measuring means relative to the workpiece in the axial direction to measure the machining diameter of the workpiece circumferential surface. It is configured to detect the position in the axial direction, which is a preset diameter, and to measure these intervals by the axial length measuring means,
The computing means is configured to obtain the axial length of the straight surface based on the measurement result by the axial length measuring means and the angle of each tapered surface, and to obtain the difference between the length and its target value. And
The control means is configured to relatively feed the grinding wheel and the second tapered surface of the workpiece in the cutting direction so as to grind the second tapered surface so that the difference is eliminated. Grinding equipment. The grinding apparatus according to claim 6, wherein
The calculation means obtains a grinding amount in a radial direction of the second tapered surface when the second tapered surface is ground so as to eliminate the difference based on the difference and the angle of the second tapered surface. The control means is configured so that the grinding wheel and the workpiece are measured while measuring the machining diameter of the second tapered surface by the machining diameter measuring means so that the second tapered surface is displaced in the radial direction by the grinding amount. A grinding apparatus, wherein the second taper surface is relatively fed in the cutting direction. In the grinding device according to claim 6 or 7,
The machining diameter measuring means includes a pair of contact pieces that are displaceable in the radial direction of the workpiece and have spherical contact portions, and measures the machining diameter by bringing each contact piece into contact with the workpiece circumferential surface. And the calculation means corrects a measurement error of a machining diameter associated with a deviation in the axial direction between the contact position of the contact portion with respect to the tapered surface and the center of the contact portion, and then determines the axial length of the straight surface. A grinding apparatus, characterized in that it is configured to obtain

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