JP2008221420A - Cylindrical grinding machine and chamfering method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylindrical grinding machining capable of forming a chamfer with high accuracy and a chamfering method using the same. <P>SOLUTION: First, a center coordinate G<SB>1</SB>in a xy coordinate system of a virtual circle 31C passing both ends E and T<SB>1</SB>of the chamfer to be formed on an outer surface of a workpiece W is determined. Second, a rotary angle β<SB>1</SB>formed by a reference straight line RL connecting the center coordinate G<SB>1</SB>and a center of the workpiece W and a x-axis is determined. Third, cutting amount δ<SB>1</SB>to be a length along the reference straight line RL in a part in which the workpiece W and the virtual circle 31C are overlapped is determined. The chamfer is formed based on the rotary angle β<SB>1</SB>and the cutting amount δ<SB>1</SB>. Subsequently, a chamfer having both ends to be codes T<SB>1</SB>and T<SB>2</SB>in the figure and a chamfer having both ends to be codes T<SB>2</SB>and B<SB>3</SB>in the figure are formed by the same method. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cylindrical grinder and a chamfering method using the same.

2. Description of the Related Art Conventionally, there has been provided a cylindrical grinder that grinds the outer surface of a columnar or cylindrical (hereinafter, “cylindrical”) workpiece with a rotating grindstone. This cylindrical grinder can be used for processing of almost any kind of part as long as the final product form is a machine part. For example, this cylindrical grinding machine is used for processing the outer surface of a valve spool or the like that constitutes a hydraulic valve for a hydraulic power steering apparatus.
As such a cylindrical grinder, for example, one disclosed in Patent Document 1 is known. In Patent Document 1, a cylindrical grinder capable of performing high-precision grinding is disclosed, and in particular, a cylindrical grinder with a workpiece driving device that performs rotational indexing is disclosed.
JP-A-9-117812

  By the way, according to the cylindrical grinding machine, so-called chamfering can be performed. The chamfering process generally means a chamfering process, but includes a process of scraping a part of the outer surface of a cylindrical workpiece to create a flat surface (in this specification, such a flat surface is referred to as a chamfering process). It is called “Changhwa”.) In particular, in accordance with the processing of the valve spool, it can be said that the chamfering process at the corner between the outer surface and the groove wall formed on the outer surface corresponds to the chamfering process. The groove generally has a form extending along the axis of the cylindrical valve spool.

  When processing such a valve spool, processing that can be called multi-stage chamfering processing may be performed. Here, the multi-stage chamfering process is, for example, as follows. That is, 1) As described above, chamfering is performed on the corner between the groove and the outer surface. 2) Subsequently, chamfering is performed on the corner between the surface formed in 1) and the original outer surface. 3) Further, it seems that chamfering is performed on the corner between the surface formed by 2) and the original outer surface. In principle, such a process can be repeated any number of times. Such processing is performed in order to realize a more delicate or smoother operation mode of the hydraulic valve.

  However, it is extremely difficult to perform the above-described chamfering process, particularly the multi-stage chamfering process (and performing it with relatively high accuracy). This is because when performing multi-stage chamfering, as described above, it is necessary to shift the portion to be ground sequentially and little by little, and each time the relative position between the workpiece and the grindstone is increased. This is because positioning must be performed appropriately.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a cylindrical grinder capable of forming a chamfer with high accuracy and a chamfering method using the same.

  In order to achieve the above object, a cylindrical grinding machine according to the present invention includes a workpiece holding means for holding a columnar or cylindrical workpiece rotatably around its central axis, and a disc-shaped grindstone at its center. A grindstone holding means capable of holding the grindstone rotatably as a shaft and translating the grindstone toward the workpiece; driving and controlling the work holding means so as to rotate the workpiece by a predetermined angle; and Control means for driving and controlling the grindstone holding means so as to translate the grindstone by a predetermined distance, and the control means is a virtual circle passing through both ends of the chamfer to be formed on the work outer surface of the work. A center coordinate in a fixed coordinate system, a processing angle formed by a reference straight line connecting the center coordinate and the center of the workpiece and a fixed straight line on the coordinate system, and the workpiece and the workpiece A cutting amount that is a length along the reference straight line in a portion where a virtual circle overlaps is calculated, the workpiece is rotated through the workpiece holding means by the predetermined angle based on the machining angle, and the workpiece After the rotation, the chamfer is translated by rotating the grindstone through the grindstone holding means for the predetermined distance based on the cutting depth, so that a chamfer is actually formed on the outer surface of the workpiece. And

  In the cylindrical grinder according to the present invention, the control means may be configured to form two or more chamfers.

  In the cylindrical grinding machine according to the present invention, the control means includes one or more chamfers, and at least one chamfer is a wall surface that forms a groove formed in advance on the work outer surface. You may comprise so that it may form about the corner | angular part between the said work outer surfaces.

  In the cylindrical grinder according to the present invention, the control means forms at least two chamfers, and forms a first chamfer, which is one of the chamfers, on a groove formed in advance on the work outer surface. An n-th chamfer (n is an integer of 2 or more), which is formed at a corner between a wall surface and the outer surface of the workpiece, and is another one of the chamfers, is replaced with an (n-1) -th chamfer and the outer surface of the workpiece. You may comprise so that it may form about the corner | angular part between.

  Moreover, in order to solve the said subject, the chamfering method using the cylindrical grinder which concerns on this invention is the cylinder which grinds the workpiece | work outer surface of a columnar or cylindrical workpiece | work with the outer peripheral surface of a rotating disk-shaped grindstone. A method for chamfering a workpiece outer surface using a grinding machine, the step of obtaining a center coordinate in a fixed coordinate system of a virtual circle passing through both ends of a chamfer to be formed on the workpiece outer surface, and the center coordinate And a step of calculating a processing angle formed by a reference straight line connecting the centers of the workpieces and a fixed straight line on the coordinate system, and a length along the reference straight line at a portion where the work and the virtual circle overlap. A step of calculating a cutting depth, a workpiece rotation step of rotating the workpiece around its central axis by a predetermined angle based on the machining angle, and after the workpiece rotation step, the grindstone, Be to translate a predetermined distance based on the serial depth of cut toward the workpiece, characterized in that it comprises a step of forming a chamfer on reality the workpiece outer surface.

  In the chamfering method using the cylindrical grinding machine according to the present invention, at least two chamfers may be formed.

  In the chamfering method using the cylindrical grinder according to the present invention, at least one chamfer is formed, and at least one of the chamfers has a groove formed in advance on the outer surface of the workpiece. You may comprise so that it may form about the corner | angular part between the wall surface to form and the said workpiece | work outer surface.

  In the chamfering method using the cylindrical grinder according to the present invention, at least two chamfers are formed, and the first chamfer that is one of the chamfers is formed in advance on the outer surface of the workpiece. An n-th chamfer (n is an integer of 2 or more), which is formed at a corner between a wall surface forming a groove and the outer surface of the workpiece, and is one of the chamfers, is an n-1th chamfer. And the outer surface of the workpiece.

  As described above, according to the present invention, since the rotation angle and the cutting amount are suitably calculated, it is possible to form the chamfer with high accuracy.

  Hereinafter, an embodiment of the present invention will be described with reference to FIG. The cylindrical grinding machine 1 according to the present embodiment includes a bed 10, a spindle stock 20, a tailstock 23, a table 26, and a grindstone 31.

The headstock 20 includes a gripping portion 21 that supports the workpiece W and a rotating portion.
As shown in FIG. 1, the grip portion 21 includes a claw that can be opened and closed. One end of the workpiece W is gripped when the nail is closed, and released when it is opened. However, the means for supporting the workpiece W may be a system other than the system using the claws, and may be employed in the present invention. In some cases, for example, the same configuration as that of the center 25 provided in the tailstock 23 described later may be provided.
Note that the work W in FIG. 1 is illustrated by a broken line indicating the position occupied by the work W when machining on the work W is being executed.

  The rotating unit (not shown) rotates the workpiece W around the axis A1 shown in FIG. Thereby, the workpiece | work W can be positioned so that the arbitrary parts of the outer surface may be made to oppose the grindstone 31. FIG. That is, the rotating portion is used to adjust the relative positional relationship between the workpiece W and the grindstone 31 (will be touched again later with reference to FIG. 3 and the like).

  As shown in FIG. 1, the tailstock 23 has a center 25 that protrudes toward the headstock 20. The tailstock 23 has a projecting mechanism (not shown) for projecting the center 25 to the left side in the drawing. The center 25 is subjected to an elastic force using a spring (not shown) as a generation source. Thereby, the core push stand 23 can push the right end of the work W in the figure with a predetermined force via the center 25.

  The headstock 20 and the tailstock 23 are installed on a table 26. The table 26 is provided with a translation drive unit (not shown). This translation drive unit drives the head stock 20 and the entire core stock table 23 together with the table 26 in the left-right direction in FIG. 1 (hereinafter, also referred to as “Z direction”). Such movement follows the extending direction of the rails 29 and 29.

  Note that the workpiece W is fixed by the table 26, the headstock 20, and the tailstock 23, for example, as follows. First, one end of the workpiece W is gripped by the grip portion 21 of the head stock 20 fixed at an appropriate position on the table 26. Second, the tailstock 23 is positioned at an appropriate position on the table 26 according to the length of the workpiece W. Third, the center 25 of the core presser 23 is protruded to the left in the figure, and the other end of the work W is pushed. At this time, the center 25 presses the work W by the elastic force. As described above, the workpiece W is fixed by the cooperation of the spindle stock 20 and the core presser 23.

Instead of the core pusher 23, a spindle head similar to the spindle head 20 having the grip portion 21 described above may be provided.
Further, the core presser 23 is not necessarily provided. In this case, one end of the workpiece W is only supported by the grip portion 21 of the head stock 20.

  As shown in FIG. 1, the grindstone 31 has a substantially disk shape. One end of a rotating shaft (not shown) passes through the center, and the other end is connected to the grindstone holder 32. That is, the grindstone 31 is held on the grindstone holding table 32 via the rotating shaft. The rotating shaft and the grindstone 31 are fixedly connected.

  The grindstone holding base 32 has a rotating part (not shown) that applies rotational power to the rotating shaft. Thereby, the grindstone holding base 32 has an ability to rotate the disc-shaped grindstone 31 around the axis A2 shown in FIG.

Further, the grindstone holding base 32 has a translation drive unit (not shown) for moving the grindstone holding base 32 itself in the vertical direction in FIG. 1 (hereinafter also referred to as “X direction”). The movement of the grindstone holder 32 follows the extending direction of the rails 33 and 33.
Thereby, the grindstone 31 can approach the workpiece | work W supported by the headstock 20, and can contact further. By such contact, the outer surface of the workpiece W is ground by the outer peripheral surface of the rotating grindstone 31. In addition, progress of grinding is based on the further movement to the direction where the workpiece | work W exists of the grindstone 31 by the said translation drive part.

  In the figure, the width of the grindstone 31 (the length in the Z direction in FIG. 1) is relatively small with respect to the workpiece W, but this is merely an example. For example, a grindstone having a width substantially the same as the length of the work W may be used. In some cases, a grindstone larger than the length of the work W may be used.

In addition to the above configuration, the cylindrical grinding machine of the present embodiment has a control unit 100.
The control unit 100 stores a processor (not shown), a ROM (Read Only Memory) that stores a program that defines a processing procedure by the processor, a program that is executed in response to an appropriate numerical input by a user, and necessary information. RAM (Random Access Memory) is provided.

The control unit 100 controls the components described above, that is, the headstock 20, the table 26, the grindstone holding table 32, and the like. Thereby, each of rotation of the workpiece | work W by the headstock 20, the movement of the headstock 20 and the tailstock 23 via the table 26, the movement and rotation of the grindstone 31 by the grindstone holding base 32, etc. is suitably set. It can be done in.
Especially in this embodiment, the control part 100 sets suitably the relative positional relationship of the workpiece | work W and the grindstone 31 in forming a chamfer using such capability. For this reason, the control unit 100 further has an ability to calculate a suitable rotation angle and depth of cut of the workpiece W, which will be described later, which will be described in detail later.

  Next, the operation of the cylindrical grinding machine 1 configured as described above will be described. In the present embodiment, description will be given by taking as an example a case where a cylindrical workpiece W is processed into a shape having a groove WG and three chamfers C1, C2, and C3 as shown in FIG. Do.

  In FIG. 2, the workpiece W facing in the axial direction is circular, and a groove WG is formed on the right side in the drawing. The cross-sectional shape of the groove WG corresponds to a substantially rectangular shape in which the side extending in parallel with the radial direction of the workpiece W is slightly longer than the other sides. Further, the groove WG extends for a predetermined length along the central axis of the cylindrical workpiece W (that is, in the vertical direction toward the paper surface of FIG. 2).

  Chamfers C1, C2, and C3 are formed above the groove WG in the figure (see the broken line in the figure). Among these, as shown in FIG. 2, the chamfer C1 is formed by chamfering a corner portion between the upper wall surface in the drawing forming the groove WG and the outer peripheral surface of the workpiece W. Further, the chamfer C2 is formed by chamfering a corner portion between the flat surface formed as the chamfer C1 and the outer peripheral surface of the workpiece W, and the chamfer C3 is formed with the flat surface formed as the chamfer C2. The corner portion between the workpiece W and the outer peripheral surface is formed by chamfering.

Each of such chamfers C1, C2, and C3 has both ends as shown in the figure. That is, both ends of the chamfer C1 refers to both points shown in FIG. 2 code E and T _1. For even chamfer C2 and C3, similarly respectively, _{T 1} and _{T 2,} as well, each two points indicated by _{T 2} and _{B 3,} is their opposite ends.
Thus, in the present invention, in general, the “both ends of the chamfer” means “the chamfer and the other chamfer adjacent to the chamfer that are seen when the work is faced in the axial direction”. It is used as a term indicating “intersection point”.

The formation of the chamfers C1, C2, and C3 described above, that is, chamfering processing is ideally performed according to ideal processing straight lines L1, L2, and L3 shown in FIG. For example, with respect to chamfer C1, the chamfer C1 is ground by a cutting amount ε ₁ which is grasped as a distance between the ideal machining straight line L1 and the tangent line of the contour circle of the workpiece W drawn parallel thereto. (The same applies to chamfers C2 and C3. See ε ₂ and ε _{3 in the} figure. Note that these ε ₁ , ε ₂ and ε ₂ are respectively shown below.) These will be referred to as the first, second and third ideal depths of cut).

In the actual processing using the above-described cylindrical grinding machine 1, it is impossible to realize the ideal shape as shown in FIG. Of course it is desirable to do.
However, this is extremely difficult. In particular, when performing multi-stage chamfering as shown in FIG. 2, it is necessary to appropriately position the grindstone 31 relative to the workpiece W each time according to the chamfers C1, C2, and C3. This increases the difficulty of realizing the ideal shape.
This is because if the position of the groove WG is regarded as normal, it is required that the chamfers C1, C2 and C3 are formed at a kind of special position on the work W, and the disc-shaped grindstone 31 is used. This is because it is required to create a flat surface while processing a cylinder or an outer surface of the cylinder (that is, processing by contacting two circles). In this case, as will be described later with reference to FIG. 3, the portion to be ground is not located on the line connecting the rotation center of the grindstone 31 and the rotation center of the workpiece W.
Because of this, it is not immediately clear how to set the grindstone 31 at the beginning of processing. In addition, since the cutting depth varies depending on the setting mode, it is not immediately clear how much the setting should be.
As described above, it is difficult to form ideal chamfers C1, C2, and C3.

  Therefore, in this embodiment, in order to form ideal chamfers C1, C2, and C3 as much as possible, the relative positional relationship between the workpiece W and the grindstone 31 is determined using the following method.

First, as a premise for explaining the method, various symbols described below are introduced in advance. In the following description, an xy plane coordinate system as shown in FIG. 2 is mainly assumed (this coordinate system is different from the coordinate system shown in FIG. 1). This xy plane coordinate system has an origin at the center O of the workpiece W, and its x axis halves the volume of the groove WG and coincides with the line.
In the following, the symbol ““ ”” is used to represent a vector, for example, when a vector of symbol A is represented, according to a general notation, it is represented by “bold A”. This is expressed as ““ A ””.

(1) Intersection of ideal machining line and workpiece contour, etc. The intersection of ideal machining line L1 and workpiece W is defined as A ₁ and B ₁ as shown in FIG. 2 (the former is a black circle, The latter is represented by a white circle, and the same applies to A ₂ and B ₂ , A ₃ and B ₃ later). And these A ₁ and B ₁ vectors are respectively
“A” ₁ = (a _1x a _1y ) ^T , “B” ₁ = (b _1x b _1y ) ^T
It is determined.
Also, the intersections A ₂ and B ₂ between the ideal machining straight line L2 and the contour of the workpiece W, and the intersections A ₃ and B ₃ between the ideal machining straight line L3 and the contour of the workpiece W are exactly the same.
“A” ₂ = (a _2x a _2y ) ^T , “B” ₂ = (b _2x b _2y ) ^T
“A” ₃ = (a _3x a _3y ) ^T , “B” ₃ = (b _3x b _3y ) ^T
It is determined.
Further, for the intersection T ₁ between the ideal machining lines L1 and L2 and the intersection T ₂ between the ideal machining lines L2 and L3, the vector
“T” ₁ = (t _1x t _1y ) ^T , “T” ₂ = (t _2x t _2y ) ^T
It is determined.

(2) Ideal machining angle The angle formed by a vertical line (hereinafter referred to as perpendicular line "PL", see FIG. 3) from the center O of the workpiece W to the ideal machining straight line L1 and the horizontal line (x axis) is shown in FIG. as shown in, the alpha _1. Hereinafter, the angles α ₂ and α ₃ are similarly defined for the ideal processing curves L2 and L3. These angles α ₁ , α _2, and α ₃ are hereinafter referred to as first, second, and third ideal machining angles, respectively.

(3) Other symbols Let r be the radius of the workpiece W. The width of the groove WG (the length in the vertical direction in FIG. 2) is 2h. If this symbol h is used, the point E that has already been described as one of both ends of the chamfer C1 can be described as the intersection of the straight line y = h and the ideal machining line L1.
In addition to the above, symbols other than those described above are also used below, but they will be introduced at appropriate points in the following description.

In the above preparation, first, each of the above-described vectors “A” ₁ , “B” ₁ , “A” ₂ , “B” ₂ , “A” _3, and “B” ₃ represents the workpiece W described above. Using the radius r and the first to third ideal machining angles α ₁ , α _2, and α ₃ , it can be expressed as follows.

Of these equations, for example, [Equation 1] relating to the vectors “A” ₁ and “B” ₁ can be derived by focusing on the triangle OA ₁ B ₁ in FIG.
That is, first, of the sides constituting the triangle OA ₁ B ₁ , the lengths of the sides OA ₁ and OB ₁ are r (OA ₁ = OB ₁ = r), and the first ideal machining angle α ₁ is defined. Since the length between the intersecting point of the perpendicular line PL and the side A ₁ B ₁ (named specifically in this paragraph as D) and the center point O is (r−ε ₁ ), the side A ₁ B ₁ 1/2 of the length is SQR (2rε ₁ −ε ₁ ² ) (where “SQR” represents a root number, and the same applies in the following description). This corresponds to a k ₁ in equation (1). After that, using the fact that the angle formed between the side A ₁ B ₁ and the y axis is α ₁ , for example, using the fact that the vector “A” ₁ is obtained by combining the vector OD and the vector DA ₁ , [Equation 1] is obtained.
The same applies to [Equation 2] for the vectors “A” ₂ and “B” ₂ and [Equation 3] for the vectors “A” ₃ and “B” ₃ .

On the other hand, the vectors “T” ₁ and “T” ₂ described above can be expressed as follows.

Of these equations, for example, in the equation [Equation 4] relating to the vector “T” ₁ , P ₁ represents the slope of the straight line A ₁ B ₁ (ie, the ideal machining straight line L1), and Q ₁ represents its intercept. Similarly, P ₂ represents the slope of the straight line A ₂ B ₂ (that is, the ideal machining line L 2), and Q ₂ represents the intercept thereof. [Equation 4] is expressed by using these P ₁ , Q ₁ , P ₂ and Q ₂ , and solving the simultaneous equations consisting of the equation of the straight line A ₁ B ₁ and that of the straight line A ₂ B ₂ , Derived.
The same applies to [Equation 5] concerning the vector “T” ₂ .

Furthermore, the intersection E between the ideal processing line L1 and the straight line y = h, the vector, defined as "E" ^{_{= (e x e y) T}} . The vector “E” indicates that the ideal machining straight line L1 can be expressed as y = P ₁ x + Q ₁ as described above, and x = (h−Q ₁ ) / P ₁ is derived from this and y = h. Use
"E" ^{_{= (e x e y) T}} = ((h-Q 1) / P 1 h) T ... (0)
(For P ₁ and Q _1, see the above [Equation 4]).

  Naturally, each vector obtained in this way is premised on ideal processing.

Well Subsequently, as shown in FIG. 3, assume a virtual circle 31C of radius R passing through the E and the point T ₁ point corresponding to both ends of the chamfer C1, to the center and G _1. The “virtual circle 31 </ b> C” in this case is nothing but the one assumed for the grindstone 31 (therefore, the radius R should be determined based on the diameter of the grindstone 31 to be actually used). Then, the vector "G" ₁ of the center G _1, in the same manner as the vector described above,
“G” ₁ = (g _1x g _1y ) ^T
It is determined.

This vector “G” ₁ includes a vector “V” for the midpoint V of the line segment ET ₁ (see the hatched circle in FIG. 3) and a vector “H” from the midpoint V to the center G ₁ of the virtual circle 31C. By using
“G” ₁ = “V” + “H”
It can be expressed as Furthermore, the vector “V” among them is the vector “E” and “T” ₁ introduced so far.
“V” = “E” +1/2 (“T” ₁ − “E”)
After all,
“G” ₁ = 1/2 (“T” ₁ + “E”) + “H”
It becomes.

Here, the direction of the vector “H” completely coincides with the inclination of the perpendicular line PL that defines the first ideal machining angle α ₁ . Thus, using its magnitude H, the vector “H” is
“H” = (Hcosα ₁ Hsinα ₁ ) ^T
It can be expressed as. In this expression, H is a right triangle having a radius R of the virtual circle 31C as a hypotenuse and 1/2 · | (“T” ₁ − “E”) | Means the length of the remaining side.
Above, and, | "T" ₁ - "E" _{| = (t 1y -e y)} / cosα 1 ( vector ( "T" ₁ - "E") and the angle of the y-axis is the alpha ₁ Note that there is, eventually, the vector “G” ₁ is

It can be expressed as

The significance of this vector “G” ₁ is as follows.
The arrangement relationship between the virtual circle 31C and the workpiece W shown in FIG. 3 represents the most desirable arrangement relationship between the grindstone 31 and the workpiece W at the end of machining of the chamfer C1, if the virtual circle 31C is regarded as the grindstone 31. Yes. In other words, if the final positional relationship between the grindstone 31 and the workpiece W is as shown in FIG. 3, the chamfer C1 can be formed in a shape closest to the ideal shape. This is because, on the above definition, on the circumference of the virtual circle 31C, namely on the circumference of the grinding wheel 31, because the both ends E and T ₁ of the chamfer C1 is riding (Note that more than grindstone 31 has a disc shape, Although it is not possible to form a completely flat surface, it is naturally possible to process a curved surface that can be equated with the flat surface if the diameter of the grindstone 31 is sufficiently large. With that in mind.)

Here, as shown by a broken line in FIG. 3, a virtual circle 31C, it is moved parallel to the direction of extension of the perpendicular line PL to define a first ideal working angle alpha _1, try to assume a virtual circle 31CS. The center of the virtual circle 31CS (see the small circle by the broken line in the figure) is parallel to the perpendicular line PL and rides on a straight line ML passing through the center G1 of the virtual circle 31C. Incidentally, the midpoint V used in deriving the above [Formula 6] is also on this straight line ML (see the hatched circle in the figure).

As is clear from the assumption of the virtual circle 31CS, the contact point between the virtual circle 31CS and the outer surface of the workpiece W (this may correspond to the above-mentioned “grinding part”) is on the perpendicular line PL. Nor on the straight line ML. The straight line ML does not pass through the center O of the workpiece W. For this reason, in order to form a suitable chamfer C1, the relative positional relationship between the workpiece W and the grindstone 31 needs to be set as a special kind.
Note that FIG. 3 also shows how the coordinate system shown in FIG. 1 is represented in the case of FIG. In this case, the X axis of the shown coordinate system is parallel to the straight line RL in FIG.

As is clear from the above description, the vector “G” ₁ can be understood to directly indicate the location where the center of the grindstone 31 should be located at the end of machining.
Alternatively, from another point of view, the vector “G” ₁ can be understood as suggesting the center position of the grindstone 31 at the start of processing where the chamfer C1 can be most suitably formed.

The above discussion applies to chamfers C2 and C3 in exactly the same manner. That is, in the case the same circle and the virtual circle 31C as described above, when passing through the two ends _{T 1} and _{T 2} of the chamfer C2, and the center and _{G 2,} passing between both ends _{T 2} and _{B 3} of the chamfer C3 , With G ₃ as its center,
“G” ₂ = (g _2x g _2y ) ^T
“G” ₃ = (g _3x g _3y ) ^T
It is determined. Then, for these vectors “G” ₂ and “G” ₃ ,

Can be obtained. These vectors “G” ₂ and “G” ₃ can be understood to indicate the center position at the time of starting the processing of the grindstone 31 where the chamfers C2 and C3 can be most preferably formed, respectively.

Now, as described above, when prompted vector "G" ₁ "G" ₂ and "G" _3, followed by the vector "G" _1, using a "G" ₂ and "G" _3, The rotation angle of the workpiece W and the depth of cut, which are parameters that can be used during actual machining, are obtained.

This will be described with reference to FIG. 3 which has already been referred to, taking the vector “G” ₁ as an example.
(1) the rotation angle of the workpiece first, assuming a straight line RL connecting the center O of the center G ₁ and the workpiece W in the virtual circle 31C representing the machining end point of the above. Rotation angle beta ₁ of the workpiece W to form a chamfer C1 is defined as the angle between the straight line RL and the x-axis. Then, this rotation angle β ₁ is
tanβ ₁ = (g _1y / g _1x )
And thus
β ₁ = arctan (g _1y / g _1x )
It can be asked.

(2) Cutting amount The cutting amount δ ₁ is considered as the length along the straight line RL in the portion where the virtual circle 31C and the workpiece W overlap as shown in FIG. Then, this cutting depth δ ₁ is
| “G” ₁ | = r + R−δ ₁
So that
δ ₁ = r + R−SQR (g _1x ² + g _1y ² )
It can be asked.

The above discussion applies to the other vectors “G” ₂ and “G” ₃ other than the vector “G” _{1 in the same} manner, and the rotation angles are β ₂ and β ₃ , and the cut amounts are δ ₂ and δ. If it is ₃ ,
β ₂ = arctan (g _2y / g _2x )
β ₃ = arctan (g _3y / g _3x )
δ ₂ = r + R−SQR (g _2x ² + g _2y ² )
δ ₃ = r + R−SQR (g _3x ² + g _3y ² )
It can be asked.

If the rotation angles β ₁ , β ₂ and β _{3 of} the workpiece W and the cut amounts δ ₁ , δ ₂ and δ _{3 obtained} as described above are used, the machining of the chamfers C1, C2 and C3 is performed. Can be done very accurately. For example, the chamfer C1 rotates the workpiece W in which the groove WG is formed in advance by the rotation angle β ₁ , and then rotates the grindstone 31 with the cutting amount δ ₁ in FIG. It is formed very accurately by translational movement in the X-axis direction. In this case, the translational motion in the X-axis direction means a translational motion in which the center of the grindstone 31 follows the straight line RL.

The control unit 100 determines the values of the rotation angles β ₁ , β _2, and β ₃ according to the shapes and positions of the chamfers C1, C2, and C3 to be actually formed based on the grounds as described above. And the values of the cutting depths δ ₁ , δ ₂ and δ ₃ are specifically calculated.
Hereinafter, the flow of processing by the control unit 100 will be described with reference to FIG.

First, the control unit 100 calculates the center coordinates of the virtual circle (step S1). Here, the “virtual circle” is a circle whose circumference rides on both ends of the chamfer to be formed or to be formed. For example, the virtual circle 31C in FIG. Needless to say, the “center coordinates” of the virtual circle correspond to the vectors “G” ₁ , “G” ₂ and “G” ₃ described above.
Further, “both ends of the chamfer” referred to here corresponds to E and T ₁ , T ₁ and T ₂ , or T ₂ and B ₃ , respectively, according to FIG.
Note that the central coordinates in this case are naturally calculated from known values. For example As for _{e x} and _{e y} in represent a vector "G" ₁ [6], by substituting the these _{e x} and _{e y} (0) equation, _{P 1} and Q in the (0) equation ₁ is substituted with P ₁ = − (1 / tan α ₁ ) and Q ₁ = a _1y + (a _1x / tan α ₁ ) described in [Equation 4], and a _1x and a in the expression of Q ₁ are further substituted. _It seems that [Equation 1] is substituted for _1y . The same applies to other symbols.

Subsequently, the control unit 100 calculates an angle formed by the x-axis and the reference straight line connecting the center coordinates calculated in step S1 and the center of the workpiece (step S2). Here, the “reference straight line” corresponds to, for example, the straight line RL shown in FIG. However, in the calculation process relating to the vectors “G” ₂ and “G” ₃ , naturally, a straight line (not shown) different from the straight line RL corresponds to the “reference straight line”.
The “angle” corresponds to the rotation angles β ₁ , β ₂ and β ₃ described above. Hereinafter, this “angle” is referred to as “rotation angle β” as shown in FIG.

Subsequently, the control unit 100 calculates a length along the reference straight line at a portion where the virtual circle and the workpiece overlap (step S3). The “length” corresponds to the cutting amounts δ ₁ , δ ₂ and δ ₃ described above. Hereinafter, this “length” is referred to as “cut amount δ” as shown in FIG.

  The center coordinates, the rotation angle β, and the cutting depth δ are calculated by the number corresponding to the number of chamfers to be formed, as is clear from the matters already described. It will be.

  When the rotation angle β and the cutting depth δ are obtained as described above, the control unit 100 proceeds to a stage of actually machining the workpiece W (see FIG. 4).

First, the control unit 100 rotates the workpiece W by an angle corresponding to the rotation angle β of the chamfer to be formed first (step S4). Speaking in line with chamfer C1 in FIG. 2, a rotation by the rotation angle beta _1. Thereby, the relative positional relationship between the workpiece W and the grindstone 31 is suitably set.
Regarding the machining of the second and subsequent chamfers, it must be considered that the workpiece W has already been rotated by a certain angle until immediately before that. For example, when the formation of the chamfer C2 of FIG. 2 is to be performed from now on, the workpiece W has already been rotated by the rotation angle β ₁ , so that it is rotated by β ₂ −β ₁ . In general, when the m-th (m is an integer of 2 or more) chamfer Cm is to be formed, the workpiece W is rotated by β _m −β _m−1 .

Subsequently, the control unit 100 moves the grindstone 31 by a distance based on the cutting depth δ, and grinds the workpiece W (step S5). During the translational movement of the grindstone 31, the grindstone 31 remains rotated.
When there are a plurality of chamfers to be formed as shown in FIG. 2, the actual processing stage is repeatedly performed by that number (step S6).
In addition, when the groove WG is formed as shown in FIG. 2, it is normal that chamfers having the same shape are formed on both sides of the groove WG. For example, referring to FIG. 2, chamfers C4, C5, and C6 (all not shown) corresponding to the chamfers C1, C2, and C3 are formed below the groove WG in the drawing. Even in such a case, the center coordinate, the rotation angle β, and the cutting amount δ can be calculated by a procedure that is essentially different from the procedure described above. Therefore, this case also corresponds to a case where there are a plurality of chamfers to be formed, and actual processing is repeatedly performed according to step S6 of FIG.
Incidentally, the control of the cylindrical grinding machine 1 (more specifically, the drive control of the headstock 20, the grindstone holding base 32, etc.) itself based on the rotation angle and the cutting amount having specific values as described above. If it pays attention to, it is not particularly strange, and there is no difference from the conventional cylindrical grinding technique.

According to the cylindrical grinding machine 1 according to the present embodiment described above, the following operational effects are exhibited.
That is, according to the cylindrical grinding machine 1 of the present embodiment, as described above, since the relative arrangement relationship between the workpiece W and the grindstone 31 can be suitably set in forming the chamfer, the chamfer is possible. As long as it can be formed exactly as designed.

Moreover, this effect can also be obtained from the above description of the calculation of the central coordinates or vectors “G” ₁ , “G” ₂ and “G” _{3 and} the calculation of the rotation angle β and the cutting depth δ or the process thereof. Obviously, it can be enjoyed in exactly the same way no matter how many chamfers are to be formed or whether there is a groove WG. This is because the calculation principle or calculation process has nothing to do with the number of chamfers. In this respect, in particular, in the case where a plurality of chamfers are formed, it can be said that the present embodiment has extremely advantageous effects in light of the fact that the difficulty of accurate processing has increased.

  In the following, some points that could not be touched in the above embodiment will be supplemented.

(1) In the above embodiment, the first, second and third ideal machining angles α ₁ , α ₂ and α ₃ are all larger than 0 and smaller than π / 2 [rad] on the premise of FIG. Although the description has been made with the case in mind, in the present invention, the following cases can be assumed in addition to such a configuration.

That is, as shown in FIG. 5, the ideal machining angle is 0 (hereinafter, this ideal machining angle is referred to as α ₀ (that is, α ₀ = 0)).
In this case, for the vector “EU” (see the point EU in FIG. 5) corresponding to the vector “E” in FIG.
“EU” = (eu _x eu _y ) ^T = (r−ε h) ^T (0) ′
Is used. Here, ε is an ideal depth of cut grasped as a distance between the tangent line of the contour circle of the workpiece W and the ideal machining straight line LX when there is no groove WG.

After using the vector "EU", and the center coordinates of the virtual circle (see the broken line in FIG. 5) passing through the EU and the point T ₁₁ points are the end points of the chamfer CX1, the center of the center coordinates and the workpiece W If a reference straight line connecting the two is obtained, and further, a machining angle and a cutting amount are obtained based on the reference straight line, a suitable chamfer machining can be performed in the same manner as in the above-described embodiment.

Note that after forming the chamfer CX1, it is naturally possible to carry out multi-stage chamfer processing such as chamfers CX2, CX3,... In the same manner as in FIG. In this case, instead of the point T ₁₁ in the, with T ₁₀₁ points shown in FIG. 5, it may be stomping the preceding steps. Furthermore, the vector "T" ₁₀₁ about point T ₁₀₁ in this case can be obtained by the same procedure as was determined [Formula 4] and [Equation 5] described above.
Also in chamfer CY1, relates the point ED and the point _{T 12,} it stomping similar to the above procedure.

(2) In the above embodiment, various formulas for determining the rotation angle β and the cutting depth δ are introduced, but the expression method is merely an example. For example, α ₁ , α ₂ and α ₃ in the above [Equation 6] and [Equation 7] are respectively shown below.
gamma ₁ = arctan _{[(e x -t 1x) / (} t 1y -e y) ]
γ ₂ = arctan [(t _1x −t _2x ) / (t _2y −t _1y )]
γ ₃ = arctan [(t _2x −b _3x ) / (b _3y −t _2y )]
It is possible to replace

According to such an expression method, the vectors “G” ₁ , “G” ₂ and “G” ₃ are expressed only by the coordinates of the end points of the chamfers C1, C2 and C3. This expression method can be said to be more generalized from the viewpoint that the ideal machining angles α ₁ , α _2, and α ₃ do not have to be used.
In any case, since the present invention is a technical idea centered on obtaining the machining angle and the cutting depth from the center coordinates of the virtual circle and the reference straight line, what the specific method will be. However, it is not basically sticking.

(3) In the above embodiment, the rails 29 and 29 are used for the movement of the table 26, and the rails 33 and 33 are used for the movement of the grindstone holding base 32. It is not limited to such a form. For example, instead of the rails 29 and 29 or the rails 33 and 33, a sliding guide may be used. It goes without saying that whatever mechanism is used basically does not relate to the essence of the present invention and is within the scope thereof.

It is a top view of the cylindrical grinding machine which concerns on embodiment of this invention. It is a figure which shows an example of the chamfer which should be formed in a workpiece | work outer surface. It is a figure which shows an example of a virtual circle. It is a flowchart of the processing method of this embodiment. It is a figure which shows the other example of the chamfer which should be formed in a workpiece | work outer surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylindrical grinding machine 10 Bed 20 Main stock stand 21 Grasp part 23 Core pushing stand 25 Center 31 Grinding wheel
32 grinding stone holder 29, 33 rail 100 controller W workpiece WG grooves C1, C2, C3, CX1, CX2, CX3, CY1 chamfer L1, L2, L3, LX ideal machining linear _{α 1, α 2, α 3} , α 0 Ideal machining angles ε ₁ , ε ₂ , ε ₃ , ε Ideal depth of cut β ₁ , β ₂ , β ₃ Rotation angle δ ₁ , δ ₂ , δ ₃

Claims (8)

A workpiece holding means for holding a columnar or cylindrical workpiece rotatably about its central axis;
A grindstone holding means for holding a disc-shaped grindstone rotatably about its center and capable of translating the grindstone toward the workpiece;
Control means for driving and controlling the work holding means to rotate the work by a predetermined angle, and driving and controlling the grindstone holding means to translate the grindstone by a predetermined distance;
With
The control means includes
Find the center coordinates of a virtual circle passing through both ends of the chamfer to be formed on the workpiece outer surface of the workpiece in a fixed coordinate system,
A processing angle formed by a reference straight line connecting the center coordinates and the center of the workpiece and a fixed straight line on the coordinate system, and a length along the reference straight line at a portion where the workpiece and the virtual circle overlap. Calculate the depth of cut
The workpiece is rotated through the workpiece holding means by the predetermined angle based on the machining angle,
After the rotation of the workpiece, the predetermined distance based on the depth of cut is translated while rotating the grindstone via the grindstone holding means,
Therefore, a chamfer is actually formed on the outer surface of the workpiece.
A cylindrical grinder characterized by that. The control means forms two or more chamfers.
The cylindrical grinding machine according to claim 1. The control means includes
Forming one or more chamfers; and
At least one of the chamfers is formed at a corner between a wall surface forming a groove formed in advance on the work outer surface and the work outer surface;
The cylindrical grinding machine according to claim 1. The control means includes
Forming at least two chamfers;
Forming a first chamfer, which is one of the chamfers, at a corner between a wall surface forming a groove formed in advance on the work outer surface and the work outer surface; and
An n-th chamfer (n is an integer of 2 or more), which is another one of the chamfers, is formed at a corner between the n-1 chamfer and the work outer surface.
The cylindrical grinding machine according to claim 1. A method for chamfering a work outer surface using a cylindrical grinder for grinding a work outer surface of a columnar or cylindrical work with an outer peripheral surface of a rotating disk-shaped grindstone,
Obtaining a center coordinate in a fixed coordinate system of a virtual circle passing through both ends of the chamfer to be formed on the outer surface of the workpiece;
Calculating a processing angle formed by a reference straight line connecting the center coordinates and the center of the workpiece and a fixed straight line on the coordinate system;
Calculating a cutting amount which is a length along the reference straight line in a portion where the work and the virtual circle overlap;
A workpiece rotation step of rotating the workpiece around its central axis by a predetermined angle based on the machining angle;
After the workpiece rotating step, the chamfer is actually formed on the outer surface of the workpiece by translationally moving the grindstone toward the workpiece by a predetermined distance based on the cutting depth; and
A chamfering method characterized by comprising:   The chamfering method according to claim 5, wherein at least two chamfers are formed. At least one chamfer is formed, and
At least one of the chamfers is formed at a corner portion between a wall surface forming a groove formed in advance on the work outer surface and the work outer surface.
The chamfering method according to claim 5. At least two chamfers are formed,
A first chamfer that is one of the chamfers is formed at a corner between a wall surface that forms a groove formed in advance on the work outer surface and the work outer surface; and
The n-th chamfer (n is an integer of 2 or more), which is another one of the chamfers, is formed at a corner between the n-1 chamfer and the outer surface of the workpiece.
The chamfering method according to claim 5.

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