JP2014008576A - Machining method and machining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve machining efficiency and machining accuracy upon forming a projecting curved surface on a work surface.SOLUTION: A sectional shape of surface of a work (30) machined with a tool (32) has nearly a W shape constituted of swollen parts swelled in the radial direction of the curved surface on the work (30) and depression sections depressed in the radial direction of the projecting curved surface on both sides of the swollen parts. A lead angle (α) is calculated, at which angle an axis (O) of the tool (32) is tilted from a normal direction of the projecting curved surface to the front side of feeding direction of the tool (D). In the situation where the tool (32) is tilted at the lead angle (α), the projecting curved surface is machined by moving the tool (32) relative to the work (30).

Description

  The present invention relates to a workpiece machining method and apparatus using a rotary tool having a bottom blade such as a face mill, an end mill, or a cup grindstone.

  Patent Document 1 discloses a curved surface cutting method capable of machining a machining surface having a relatively large area with high accuracy and high efficiency using a milling tool. In this method, the milling tool is moved in a predetermined tool feed direction in a state in which the rotation axis is inclined with respect to the normal line of the machining surface at each cutting point, so that the tool feed direction side region of the cutting blade rotation trajectory is obtained. The surface of the workpiece is cut by a cutting blade that passes through.

JP 2001-198718 A

  However, the invention of Patent Document 1 discloses that a tool is processed with a lead angle, but an optimal lead angle setting method and an optimal pick feed amount setting method for the lead angle are disclosed or suggested. In addition, there is room for further improvement in the shape accuracy and machining accuracy of the machined workpiece surface.

  The present invention has a technical problem to solve the problems of the prior art described above, and a convex curved surface is formed on the workpiece surface using a rotary tool having a bottom blade such as a face mill, an end mill, or a cup grindstone. It aims at improving the processing efficiency and processing accuracy at the time of carrying out.

  In order to solve the above-described problems, according to the present invention, in a machining method for processing a convex curved surface by feeding a rotary tool having a bottom blade to the workpiece along the convex curved surface of the workpiece, the machining is performed by the tool. The tool so that the processed surface has a bulging portion bulging in the radial direction of the convex curved surface of the workpiece, and a concave portion recessed in the radial direction of the convex curved surface on both sides of the bulging portion. A workpiece machining method for machining the convex curved surface by relatively tilting the axis of the workpiece and the convex curved surface of the workpiece is provided.

  Further, according to the present invention, in the machining method for processing the convex curved surface by feeding a rotary tool having a bottom blade to the workpiece along the convex curved surface of the workpiece, the cross section of the surface processed by the tool is: The bulging portion bulging in the radial direction of the convex curved surface of the workpiece, and the concave portion recessed in the radial direction of the convex curved surface on both sides of the bulging portion so as to be substantially W-shaped, A lead angle for tilting the axis of the tool from the normal direction of the convex curved surface to the front side in the tool feed direction is calculated, and the tool is relatively tilted with respect to the workpiece while the tool is tilted relatively with the lead angle. A workpiece machining method for machining the convex curved surface by moving the workpiece is provided.

  Furthermore, according to the present invention, in a machining apparatus provided with an NC machine tool that feeds a rotary tool having a bottom blade relative to the workpiece along the convex curved surface of the workpiece and processes the convex curved surface, A cross section of the processed surface has a bulging portion that bulges in the radial direction of the convex curved surface of the workpiece, and a concave portion that is recessed in the radial direction of the convex curved surface on both sides of the bulging portion. A lead angle for relatively tilting the axis of the tool from the normal direction of the convex curved surface to the front side in the tool feed direction is calculated so as to obtain a W shape, and the relationship between the lead angle and the shape error is obtained in advance by calculation. The bulge portion is in contact with the surface of the convex surface of the workpiece at the outermost point in the radial direction of the convex surface of the workpiece, and connects the center of rotation of the tool and the center of curvature of the convex surface formed on the workpiece. The straight line and the feed direction of the tool A simulation unit that calculates the distance between two points where the straight line perpendicular to the machining surface intersects the machining surface as a pick-feed amount, and various tool sizes and convex surface sizes of the workpiece calculated by the simulation unit , A storage unit for storing a lead angle and a pick feed amount with respect to a shape error, and a tool size, a size of a convex curved surface of a workpiece, and a shape error, when given to the NC machine tool from the data stored in the storage unit There is provided a machining apparatus including a lead angle to be set, a lead angle for determining a pick feed amount, and a pick feed amount determining unit.

  According to the present invention, when a rotary tool having a bottom blade is sent along a convex curved surface of a workpiece to process the convex curved surface, the cross section of the processed workpiece surface bulges in the radial direction of the convex curved surface of the workpiece. Specifically, the lead angle of the tool is calculated so as to be substantially W-shaped so as to have a concave portion recessed in the radial direction of the convex curved surface at both sides of the bulging portion, and Since the workpiece is processed, a convex curved surface with less shape error can be processed. At this time, if the lead angle obtained based on the allowable shape error is employed, the convex curved surface can be processed with a desired accuracy. Further, when processing with a pick feed, an optimal pick feed amount can be calculated, and a convex curved surface can be processed with high processing efficiency and good finish surface quality.

It is the schematic diagram which looked at the mode which forms a convex curved surface in a workpiece | work using a tool in the center axis direction of the workpiece | work. It is a schematic sectional drawing which shows the process shape formed in a workpiece | work. It is the schematic diagram which looked at a mode that a convex curved surface is formed in a work using a tool in the direction of the central axis of a tool. It is a schematic sectional drawing which shows the process shape formed in a workpiece | work. It is the schematic diagram which looked at a mode that a convex curved surface is formed in a work using a tool in the direction of the central axis of a tool. It is a schematic sectional drawing which shows the process shape formed in a workpiece | work. It is the schematic diagram which looked at a mode that a convex curved surface is formed in a work using a tool in the direction of the central axis of a tool. It is the model of the workpiece | work surface seen in the center axis line direction of the tool. It is a figure which shows the geometric positional relationship of the process area between a workpiece | work and a tool which expands and shows a part of FIG. It is a figure which shows typically the cross section of the workpiece | work cut | disconnected by the plane containing the radius of the workpiece | work 30 similar to FIG. 2A, 3A, 4A, and is a figure which shows (zeta) and (eta) coordinate. It is a partial expanded sectional view of the workpiece | work which shows the simulation result by this invention. FIG. 9 is a partially enlarged cross-sectional view similar to FIG. 8 showing a processed shape when the lead angle is α = 0.716 °. FIG. 10 is a partially enlarged cross-sectional view similar to FIGS. 8 and 9 showing a processed shape when the lead angle is α = 1.3 °. It is a graph which shows the relationship between a lead angle, a shape error, and the amount of pick feeds as an example. 1 is a side view of an NC machine tool according to an embodiment of the present invention. It is the elements on larger scale which show the main axis | shaft and workpiece | work of the NC machine tool of FIG. It is a side view of the face mill as an example of the tool which can be used with the machining method of the present invention. It is a block diagram which shows the structure of embodiment of the machining apparatus of this invention. It is a figure explaining the X, Y, Z-axis direction component force of the cutting force in the cutting process by a face mill. It is a graph which shows an example of the measured value of the cutting amount of a tool axial direction by a face mill, and the X, Y, Z-axis direction component force of cutting force.

  First, an NC machine tool to which the machining method of the present invention can be applied will be described with reference to FIGS. FIG. 12 is a side view of the NC machine tool according to the embodiment of the present invention, and FIG. 13 is a partially enlarged view showing the spindle and workpiece of the NC machine tool of FIG.

  Referring to FIG. 12, an NC machine tool 10 to which the machining method of the present invention can be applied is configured as a horizontal machining center, and a bed 12 serving as a base fixed to the floor of a factory, the rear of the bed 12 A column 14 is attached to the upper surface of the portion so as to be movable in the left-right direction (X-axis direction, a direction perpendicular to the paper surface in FIG. 12) via an X-axis feed mechanism, and a Y-axis feed mechanism (not shown) is attached to the front surface of the column 14. C-axis base 16 mounted so as to be movable in the vertical direction (Y-axis direction) via the Z-axis) and the front-rear direction (Z-axis direction, left and right in FIG. A table 18 movably mounted in the direction). The table 18 is fixed with the scale 28 having a vertical mounting surface 28a to which the work 30 is attached. In the present embodiment, the work 30 has a substantially cylindrical shape. A vertical machining center can be used as the NC machine tool.

An A-axis base 20 is supported on the C-axis base 16 so as to be rotatable in the C-axis direction around the Z-axis. The A-axis base 20 has bracket portions 22 on both sides across the rotation axis of the C-axis base 15. A spindle head 24 is attached to the bracket portion 22 so as to be rotatable in the A-axis direction by a rotation shaft 22a parallel to the X-axis. A main shaft 26 is supported on the main shaft head 24 so as to be rotatable about a rotation axis O _s in the longitudinal direction, and a tool 32 is attached to a tip portion of the main shaft 26.

  The X-axis feed mechanism is a pair of X-axis guide rails 12a extending horizontally in the left-right direction on the upper surface of the bed 12, and is attached to the lower surface of the column 14 so as to be slidable along the X-axis guide rails 12a. A guide block (not shown), an X-axis ball screw (not shown) extending in the X-axis direction in the bed 12, and a nut (FIG. 2) attached to the lower end portion of the column 14 and engaged with the X-axis ball screw. And a servo motor (not shown) connected to one end of the X-axis ball screw and rotationally driving the X-axis ball screw.

  Similarly, the Y-axis feed mechanism is attached to the C-axis base 16 so as to be slidable along a pair of Y-axis guide rails (not shown) vertically extending in the column 14. A guide block (not shown), a Y-axis ball screw (not shown) extending in the Y-axis direction in the column 14, and a nut (in the figure) attached to the C-axis base 16 and engaged with the Y-axis ball screw And a servo motor (not shown) that is connected to one end of the Y-axis ball screw and rotationally drives the Y-axis ball screw.

  Similarly, the Z-axis feed mechanism includes a guide block (not shown) mounted on the lower surface of the table 18 so as to be slidable along the X-axis guide rail 12b horizontally in the front-rear direction on the upper surface of the bed 12. A Z-axis ball screw (not shown) extending in the Z-axis direction, a nut (not shown) attached to the lower surface of the table 18 and engaged with the Z-axis ball screw, and one end of the Z-axis ball screw And a servo motor (not shown) that is connected to the Z-axis and rotates the Z-axis ball screw.

  A method of machining the cylindrical outer peripheral surface of the workpiece 30 using the tool 32 by the 5-axis NC machine tool 10 having the linear feed shaft and the rotary feed shaft will be described with reference to FIG. The cylindrical workpiece 30 is attached to the scale 28 so that the center axis O is perpendicular to the workpiece mounting surface 28a of the scale 28. The spindle head 24 is rotationally positioned in the A-axis direction so that the bottom blade of the tool 32 faces the cylindrical outer peripheral surface of the workpiece 30. Tool feed for machining the cylindrical outer peripheral surface of the work 30 with the bottom blade of the tool 32 is given by simultaneous three-axis operation of the X axis, Y axis, and C axis. Pick feed in the axial direction of the workpiece 30 is given by Z-axis motion. Further, the operation of tilting the rotation center axis Os of the tool 32 forward in the feed direction of the tool and providing a lead angle is given by the C axis.

  Next, referring to FIG. 14, a side face of a face mill is shown as an example of the rotary tool 32 that can be used in the machining method of the present invention. The face mill 32 is attached to a shank 36 attached to a tool attachment hole (not shown) of the main shaft 26, a cutter body 34 coupled to the shank 36, and a peripheral portion of the cutter body 34 at equiangular intervals. A plurality of chips 38 are provided. The tip 38 protrudes from the outer peripheral surface and the bottom surface of the cutter body 34, and forms the bottom blade as well as the outer peripheral blade of the face mill 32. Thus, the tool that can be used in the machining method of the present invention needs to have at least a bottom blade. Such tools include, for example, an end mill and a cup grindstone in addition to a face mill.

Hereinafter, a preferred embodiment of the machining method of the present invention will be described with reference to FIGS. 1 to 11 by taking the face mill shown in FIG. 14 as an example.
First, referring to FIG. 1 schematically showing how a convex surface is formed on the workpiece 30 using the tool 32, in this example, the tool 32 is a face mill, and a cylindrical surface as a convex curved surface on the surface 30a of the workpiece 30. Is formed. In FIG. 1, the tool 32 is inclined forward in the feed direction D _f of the tool 32 with a lead angle α. Here, the lead angle α is defined by the straight line L _m connecting the center (tool center) O _{t of the} circle drawn by the tip of the cutting edge of the tip 38 of the tool 32 and the curvature center O of the convex curved surface formed on the workpiece 30, and the tool 32. _Is an angle between the rotation center axis O _{s of} When the cylindrical outer peripheral surface is formed as a convex curved surface on the cylindrical workpiece 30 as in the present embodiment, the center of curvature O is on the central axis of the columnar workpiece 30.

Since the face mill is generally provided with cutting edges only on the outer peripheral portion of the tool, when a convex curved surface is formed with a lead angle α = 0, the cutting edges are formed on both sides of the tool 32 as shown in FIG. It contacts the workpiece 30 at the contact point P _cs , and cannot contact the front edge with respect to the tool feed direction D _f . Therefore, as shown in FIG. 2A, the cross-section of the processed shape is bulged at the center and becomes generally convex. When the tool 32 is cut until the front edge of the tool 32 comes into contact with the workpiece 30, the apex of the convex portion in FIG. 2A is lowered to the position of the two-dot chain line to be machined, resulting in a problem of excessive cutting on both sides.

On the other hand, when the lead angle α is too large, the cutting edge cannot contact the workpiece 30 on both sides of the tool 32 as shown in FIG. 3B, and the leading edge of the tool 32 with respect to the tool feed direction D _f. The contact is made only at the contact point _Pcf . Therefore, as shown in FIG. 3A, the cross-section of the processed shape has a concave shape at the center and is generally concave. If the both sides of the tool 32 are cut until they come into contact with the workpiece 30, the apex of the recess in FIG. 3A will fall below the position of the two-dot chain line to be machined, resulting in a problem of excessive cutting at the front edge.

On the other hand, when the lead angle α is an intermediate value between them, the cutting edge of the tool 32 has two contact points P _cs on both sides of the tool 32 and the tool feed direction D _f as shown in FIG. 4B. As shown in FIG. 4A, the cross section of the processed shape is in contact with the work 30 at three points of the contact point _Pcf of the front edge, and the center part bulges out of the work 30 and the work 30 on both sides thereof. It has a recess recessed inward in the radial direction, and is W-shaped as a whole.

  Next, with reference to FIG. 1 and FIGS. 5 to 7, the relationship between the machining shape, that is, the shape error that is the difference between the designed shape and the actually machined shape, and the lead angle α will be described in detail. To do. FIG. 5 is a schematic view of the surface of the work 30 viewed in the direction of the central axis of the tool 32. FIG. 6 is an enlarged view of a part of FIG. 7 is a diagram showing a geometric positional relationship, and FIG. 7 is a diagram schematically showing a cross section of the work 30 cut along a plane including the radius of the work 30 similar to FIGS. 2A, 3A, and 4A. It is a figure which shows a coordinate.

In Figure 1,6, a perpendicular line drawn from the center O of the workpiece 30 to segment P _cf P _cs a straight line L _n, the intersection of the line segment P _cf P _cs and the straight line L _n and N. Further, in FIG. 5, T _d is the tool diameter, W is the distance between the contact points P _cs of the cutting edge and the workpiece 30 on either side of the tool 32 (the processing width), S was measured in the tool feed direction D _f This is the distance (contact length) between the contact point _{Pcf on} the front edge of the tool 32 and the contact point _Pcs on one side. Further, in FIG. 7, the ζ axis is defined in parallel to the central axis O of the work 30, that is, in the machining width direction perpendicular to the feed direction of the tool 32, and the η axis is defined in the radial direction of the work 30.

First, in order to obtain the lead angle α, the contact length S between the face mill as the tool 32 and the workpiece 30 is obtained. 1 and 6, point N is a leg of a perpendicular drawn from the vertex O of the isosceles triangle OP _cf P _cs to the base P _cf P _cs , and the length of the base P _cf P _cs is as defined above. Is the contact length S. Therefore, for the triangle ONP _cf , the length h of the line segment ON can be obtained by the following equation, where R is the radius of curvature of the processed surface of the workpiece 30.
h = (R ² − (S / 2) ² ) ^1/2

Further, as understood from FIG. 1, since the line segment ON is parallel to the rotation axis O _s of the tool 32, ∠O _t ON is equal to the lead angle α as the isometric angle of the lead angle α. Accordingly, the lead angle α is obtained by the following equation.
tan α = (T _d / 2−S / 2) / h = (T _d / 2−S / 2) / (R ² − (S / 2) ² ) ^1/2 (1)
Further, the shape error δ, which is the distance in the radial direction (η-axis direction) of the workpiece 30 between the central portion bulging outside the workpiece 30 and both side portions recessed inside the workpiece 30, is expressed by the following equation. Desired.
δ = R−h = R− (R ² − (S / 2) ² ) ^1/2 (2)

In FIG. 7, assuming that the designed machining shape, in this example, the cylindrical surface is η = 0, the following equations are obtained from equations (1) and (2).
η = ((Rsin α−ζ) ² + R ² cos ² α) ^1/2 −R (3)
In Equation (3), R is a known diameter because it is the designed diameter of the work 30, and α is an unknown. Therefore, the machining shape can be simulated based on Expression (3) using the lead angle α as a parameter. FIG. 8 shows the results of simulation performed under the conditions of a tool diameter (T _d ) of 100 mm, a workpiece processing surface radius of curvature (R) of 2000 mm, a contact length (S) of 50 mm, and a processing width (W) of 100 mm. FIG. 8 shows a part of the work 30 cut along a plane perpendicular to the tool feed direction D _f of the tool 32 including the straight line L _m connecting the tool center O _t of the tool 32 and the center of curvature O of the convex curved surface formed on the work 30. It is sectional drawing. From the simulation, when the lead angle is in a certain range, in the simulation example shown in FIG. 8 as an example, in the range of 0 ° <α ≦ 1.3 °, the machining shape is W-shaped as a whole, and when α = 0.716 ° It was found that the machining shape error was the smallest when the full diameter was used.

Next, the machining method according to the present invention will be described in more detail with reference to FIGS. 9 and 10 which are enlarged views similar to FIG. 8 of the machining shape when the lead angles α = 0.716 ° and α = 1.3 °. When the lead angle is in the range of 0 ° <α ≦ 1.3 °, as shown in FIGS. 9 and 10, the processing shape is such that the central portion bulges in the radial direction of the work 30 and gradually increases inward in the radial direction on both sides thereof. It becomes a W-shape as a whole that dents and swells radially outward again at the outer portion along the ζ axis. That is, the surface of the workpiece 30 is processed into a shape having three extreme points P ₀ , P ₁ , P ₂ by one feed of the tool 32. In this way, the surface of the workpiece 30 machined by the tool 32 has a local maximum portion that protrudes outward in the radial direction of the workpiece 30 around the extreme point P ₀ , and the periphery of the extreme points P ₁ and P ₂ is the local maximum. It becomes a minimum part that is recessed radially inward on both sides of the point. This maximum portion is a bulging portion, and the minimum portion is a recessed portion.

In the present invention, it passed the extreme point P ₀ that bulges of the central portion of the machining shape, and a straight line drawn L ₀ perpendicular to both the tool feed direction D _f of the straight line L _m and the tool 32, the straight line L ₀ By defining the distance between two points P ₃ and P ₄ that intersect the machining surface as the pick feed amount F _p of the tool 32, for example, as shown in FIG. During processing along the tool path, the portion outside the extreme point P ₀ is removed, and the shape error δ is the extreme point P ₀ in the central portion that bulges outward from the workpiece 30, This is the distance in the η-axis direction between the extreme point P ₁ or P ₂ recessed inside the work 30 formed on both sides of the extreme point P ₀ . In this case, the tool path may be calculated with the offset equivalent amount _So as the distance corresponding to the distance in the η-axis direction between the vertex Pc of the cusp 40 and the extreme value point P ₀ . When the tool 32 is machined with an S _o offset in the η-axis direction, P ₀ can be positioned at a position with zero error from the designed machining shape between P _{3 and} P ₄ .

As described above, since the machining shape can be simulated by giving the lead angle α, in the present invention, as shown in FIG. 11, the relationship between the lead angle α, the shape error δ, and the pick feed amount F _p is expressed as follows. It can be calculated in advance. In FIG. 11, for example, assuming that δ = 0.05 mm is given as a design error, starting from this shape error δ = 0.05 mm, a lead angle α = 1.03 is obtained. From this lead angle α = 1.03, the pick feed amount F _p = 90 mm can be obtained. According to the present invention, this relationship is incorporated into an automatic programming system such as a CAM or an NC device of a machine tool in the form of a table or the like, and the lead angle α and the pick feed amount Fp are automatically determined from the shape error δ. Can be generated.

Next, an embodiment of the machining apparatus of the present invention will be described with reference to FIG. The machine tool 10 attached with an NC device such as a machining center processes a workpiece by a processing program sent from the CAM device 42. The machining apparatus according to the present invention further includes a lead angle / pick feed amount determination unit 46 for sending a lead angle and a pick feed amount to the NC apparatus. The lead angle / pick feed amount determination unit 46 is connected to the input unit 44 and also connected to the simulation unit 50 via the storage unit 48. As described above, the simulation unit 50 simulates the machining shape by giving the lead angle α, calculates in advance the relationship between the lead angle α, the shape error δ, and the pick feed amount F _p , and associates the results with each other. Store in the storage unit 48. The calculation in the simulation unit 50 is performed for various tool sizes and the size of the convex surface of the workpiece and stored. The form to be stored may be a function as shown in FIG. 11 or a table (not shown). In actual machining, when the tool size, the size of the convex surface of the workpiece, and the shape error are input from the input unit 44, the lead angle and pick feed amount determination unit 46 reads the lead that meets the conditions input from the storage unit. The angle and pick feed amount are obtained and determined and sent to the NC device. The NC machine processes the workpiece by adding the lead angle and pick feed amount to the machining program. The lead angle / pick feed amount determination unit 46 sends the determined lead angle and pick feed amount to the CAM device 42, and the CAM device 42 sends a machining program including the lead angle and feedback amount to the NC device. May be.

In this way, when processing a convex curved surface on a workpiece using a rotary tool having a bottom blade such as a face mill, end mill, or cup grindstone, processing is performed by setting an optimal lead angle or setting a pick feed amount. Efficiency and processing accuracy can be increased.
The workpiece shape suitable for the present invention is a convex curved surface in the feed direction of the tool, and the curved direction is a straight or convex curved surface shape in the width direction.
In the present embodiment, the NC machine tool having the A-axis or C-axis rotary feed shaft on the main shaft side has been described, but there is a rotary feed shaft on the table side, or a rotary feed shaft is provided on each of the main shaft side and the table side. The same processing can be performed with an NC machine tool. Further, the lead angle alpha, has been described with respect to a normal to the convex curved surface the direction of inclining the direction D _f forward feed the axis O _s of the tool 32 in the present embodiment, the direction of inclining the feeding direction D _f rear Can obtain similar actions and effects.

FIG. 16A is an explanatory diagram of the three component forces of the cutting force when the workpiece 30 is cut by the face mill 32, and FIG. 16B is the three component forces of the cutting force when the depth of cut in the tool axis direction is variously changed. An example of the measurement results is shown in a graph. The absolute value of the X-axis direction force component F _x and the Y-axis direction force component F _y of the cutting force increases as the tool axis direction (Z axis direction) depth of cut is large. The component force F _{z in} the Z-axis direction of the cutting force is a positive value (acts in the direction in which the tool is pushed into the spindle) in the region where the cutting depth in the tool axis direction is small, but a negative value (the tool is changed in the region where the cutting depth is large). Acting in the direction of pulling out from the main shaft). That is, there is a cutting amount in the tool axis direction where the Z-axis direction component force F _{z of} the cutting force becomes zero. In the example of FIG. 16B, the Z-axis direction component force F _z of the cutting force is almost zero when the cutting depth in the tool axis direction is 3 mm. It was also found that the quality of the machined surface was improved when cutting was performed with the cutting depth in the tool axis direction where the Z-axis direction component force F _{z of} the cutting force was zero. Therefore, the storage unit 48 also stores the value of the cutting amount in the tool axis direction when the component force of the cutting force in the Z-axis direction becomes almost zero for various tools, and the lead angle and pick feed amount. When the determination unit 46 determines the lead angle and pick feed amount, it also determines the cutting amount in the tool axis direction at which the Z-axis direction component force F _{z of} the cutting force becomes substantially zero and sends it to the NC device. As a result, the machined surface quality is further improved.

10 NC machine tool 12 Bed 14 Column 16 C-axis base 18 Table 20 A-axis base 24 Spindle head 26 Spindle 28 Equal 30 Work 32 Tool D _f Tool feed direction O Center of curvature of machining surface O _t Tool center Circle center)
S Contact length T _d Tool diameter W Machining width α Lead angle δ Shape error

Claims (6)

In a machining method for feeding a rotary tool having a bottom blade to the workpiece along the convex curved surface of the workpiece, and machining the convex curved surface,
The machining surface machined by the tool has a bulging portion that bulges in the radial direction of the convex curved surface of the workpiece, and a concave portion that is recessed in the radial direction of the convex curved surface on both sides of the bulging portion. And a workpiece machining method for machining the convex curved surface by relatively inclining the tool axis and the convex curved surface of the workpiece. In a machining method for feeding a rotary tool having a bottom blade to the workpiece along the convex curved surface of the workpiece, and machining the convex curved surface,
The cross section of the surface machined by the tool has a bulging portion that bulges in the radial direction of the convex curved surface of the workpiece, and a concave portion that is recessed in the radial direction of the convex curved surface on both sides of the bulging portion. And calculating a lead angle for tilting the axis of the tool from the normal direction of the convex curved surface to the front side in the tool feed direction so that the tool has a substantially W shape, and the tool is relatively tilted with the lead angle. A workpiece machining method for machining the convex curved surface by moving the tool relative to the workpiece.   The machining method according to claim 2, wherein a relationship between the lead angle and the shape error is obtained in advance, and the lead angle is obtained based on an allowable shape error from the relationship between the lead angle and the shape error. .   A straight line that touches the surface of the convex surface of the workpiece at the outermost point in the radial direction of the convex surface of the workpiece at the bulging portion and connects the rotation center of the tool and the center of curvature of the convex surface formed on the workpiece. And a straight line perpendicular to both the feed direction of the tool, a distance between two points intersecting the machining surface is obtained by calculation, and the distance is determined as a pick feed amount of the tool. The processing method of any one of these.   The processing method according to claim 1, wherein the tool is a face mill, an end mill, or a cup grindstone. In a machining apparatus comprising an NC machine tool that feeds a rotary tool having a bottom blade relative to the workpiece along the convex curved surface of the workpiece, and processes the convex curved surface,
The cross section of the surface machined by the tool has a bulging portion that bulges in the radial direction of the convex curved surface of the workpiece, and a concave portion that is recessed in the radial direction of the convex curved surface on both sides of the bulging portion. And calculating a lead angle for relatively inclining the axis of the tool from the normal direction of the convex curved surface to the front side of the tool feed direction so as to be substantially W-shaped, and the relationship between the lead angle and the shape error is calculated in advance. Obtained by calculation and touches the surface of the convex surface of the workpiece at the outermost point in the radial direction of the convex surface of the workpiece at the bulging portion, and the center of curvature of the convex surface formed on the workpiece and the rotation center of the tool And a straight line perpendicular to both the feed direction of the tool and a simulation unit for calculating a distance between two points intersecting the machining surface as a pick feed amount by calculation,
A storage unit for storing various tool sizes, workpiece convex surface sizes, lead angles and pick feed amounts for shape errors calculated by the simulation unit;
When the tool size, the size of the convex curved surface of the workpiece, and the shape error are given, the lead angle and pick that determine the lead angle and pick feed amount to be set in the NC machine tool from the data stored in the storage unit A feed amount determination unit;
A machining apparatus characterized by comprising:

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