JP2004058245A - Device for biasing cutting tool of machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance working accuracy by eliminating an error between a command value and an actual movement value of a cutting tool. <P>SOLUTION: By providing a cutting tool supporting arm (11) extending axially via a fulcrum (12) being orthogonally crossed with this in the axial center portion of the tip side of a spindle (10) swingable and in an impossible state of a relative rotation, by providing an engaging pin (17) parallel to the above fulcrum (12) in the rear portion of the above cutting tool supporting arm (11), by providing a draw bar (20) being moved axially in an internal deep portion of the above spindle (10), and by providing an engaging body (21) engaging slidably with the above engaging pin (17) in the above draw bar (20), a sliding face with the above engaging pin (17) of the above engaging body (21) is made as a curved face for retaining in a proportional relationship between a reciprocating movement of the above draw bar (20) and a radial movement of the tip in the cutting tool supporting arm (11). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a machine tool for performing an end face machining or a drilling process on a workpiece by attaching a tool to a spindle, and more particularly to a machine tool capable of moving and adjusting a tool rotated by a spindle in a radial direction with respect to the spindle. The present invention relates to a blade biasing device.
[0002]
[Prior art]
As a conventional technique, there has been one shown in FIGS. In FIG. 5, reference numeral 1 denotes a spindle, and 2 denotes a blade support arm attached to the distal end side (the left end side in FIG. 5) of the spindle 1. 5 is supported on the spindle 1 via a fulcrum shaft 3 so as to be vertically swingable in FIG. An engagement pin 4 is attached to a rear end (right end in FIG. 5) of the blade support arm 2. The engaging pin 4 is disposed in parallel with the fulcrum shaft 3 and is rotatably attached to the rear end of the blade support arm 2. Both ends of the engagement pin 4 protrude from both side surfaces of the blade support arm 2, and serrations are formed on the protruding end surface. 4a is formed.
[0003]
The tip of the blade support arm 2 projects forward (to the left in FIG. 5) from the spindle 1, and the blade 6 is attached to the projection via the holder 5. The blade 6 is attached to the outer periphery of the end of the holder 5 and has an initial cutting edge radius D2 (FIG. 7). Further, a draw bar 7 that is moved in the axial direction is fitted into an inner deep portion of the spindle 1, that is, an axial center portion of the spindle 1 located behind the blade support arm 2, and an engaging body 8 is attached to a front end of the draw bar 7. Attach. The engaging body 8 has two plate members facing each other, and a serration 8a extending downward and inclined straight forward is formed on the facing side, and the serration 8a is formed as shown in FIG. 4 is slidably engaged with the serrations 4a. The pressure angle of the serrations 4a and 8a is 60 degrees.
[0004]
Then, the engagement position of the serration 8a of the engagement body 8 with respect to the serration 4a of the engagement pin 4 is moved in the front-rear direction by adjusting the movement of the engagement body 8 in the front-rear direction via the draw bar 7, thereby moving the blade support arm 2 Is adjusted in the radial direction with respect to the spindle axis E of the blade 6 attached to the tip end of the blade support arm 2, that is, the blade radius D1 is adjusted.
[0005]
[Problems to be solved by the invention]
In the prior art, the serration 8a of the engaging body 8 is linear and inclined, so that the amount of movement of the cutter 6 in the radial direction with respect to the spindle axis E is not proportional to the amount of movement of the draw bar 7 in the axial direction. . For example, as shown in FIGS. 5 and 7, the distance A between the center O of the fulcrum shaft 3 and the cutting edge of the blade 6 and the distance B between the center O and the center of the engagement pin 4 are both 110 mm, and the engagement body 8 The axial movement amount C is set to 40 mm, and the inclination angle of the serration teeth 8a is set such that the radial movement amount relative to the movement amount C (radial movement amount relative to the spindle axis E) is 8 mm. 7, when the engaging body 8 is advanced from the movement fulcrum A0 to the most advanced point A2, the engagement pin 4 moves from the movement fulcrum B0 to the lowest movement point B2, and accordingly, the cutting edge of the blade 6 is moved to the movement fulcrum C0. To the maximum diameter point C2.
[0006]
In this case, since the blade 6 moves in an arc, the amount of movement of the blade 6 in the radial direction with respect to the spindle axis E (the cutting edge radius D1) gradually decreases as the engaging body 8 moves forward (from point A0 to point A2). become. That is, when the engaging body 8 is moved in the axial direction by a predetermined command value, as shown by the error curve G1 in FIG. Increases as the amount of movement of the target increases. According to the calculation, the edge radius D1 of the blade 6 at the most advanced point A2 of the engagement body 8 has an error of about 0.053 mm from the command value. Therefore, conventionally, high-precision processing becomes difficult.
[0007]
Further, in the above-mentioned conventional apparatus, when the spindle 1 rotates, a rotational moment occurs in the blade support arm 2 so that the blade 6 moves in the large-diameter direction, which is not suitable for high-speed rotation. That is, when the blade support arm 2 rotates about the axis E of the spindle 1, the rotational moment S1 on the front side and the rotational moment S2 on the rear side of the blade support arm 2 with respect to the center O of the fulcrum shaft 3 rotate the same ( In FIG. 5, it works in the right direction. In this case, the mass M1 on the front side and the mass M2 on the rear side of the blade support arm 2 with respect to the center O of the fulcrum shaft 3 are equalized, and the mass M1 on the front side with respect to the center O of the fulcrum shaft 3 is increased. Is equal to the distance L2 to the rear side mass M2, the centrifugal forces T1 and T2 of the masses M1 and M2 acting on the spindle 1 are balanced, but the rotational moments S1 and S2 are balanced. It is not possible. For this reason, in the above-mentioned conventional one, processing by high-speed rotation becomes difficult. SUMMARY OF THE INVENTION It is an object of the present invention to provide a novel tool biasing device for a machine tool that solves the above-mentioned problems.
[0008]
[Means for Solving the Problems]
The present invention is configured as follows to achieve the above object. That is, the invention according to claim 1 is characterized in that a blade support arm extending in the axial direction is provided at a shaft center portion on the tip end side of the spindle via a fulcrum shaft orthogonal to the shaft so as to be swingable and relatively non-rotatable. An engaging pin parallel to the fulcrum shaft is provided at a rear portion of the arm, a draw bar that is moved in an axial direction is provided in an inner deep portion of the spindle, and an engaging body that slidably engages with the engaging pin is provided at the draw bar. The sliding surface of the engaging body with the engaging pin is a curved surface which holds the reciprocating movement of the draw bar and the radial movement of the tip of the blade support arm in a proportional relationship.
Further, the invention according to claim 2 is provided with a weight which is a swing center of the blade support arm and is orthogonal to the swing center of the blade support arm, and which faces the swing center with the swing center interposed therebetween. The rotational moment when the spindle is rotated by the weight is made to be opposite and substantially equal to the rotational moment of the blade support arm generated when the spindle is rotated.
According to a third aspect of the present invention, an engaging pin parallel to a fulcrum axis is rotatably provided at a rear portion of the blade supporting arm, and tooth-shaped engaging teeth are formed in parallel at a predetermined pitch on an end face of the engaging pin. Then, rack teeth extending in the direction of movement of the drawbar are formed on the engaging body provided on the drawbar, and the rack teeth are moved in a proportional relationship between the reciprocating movement of the drawbar and the radial movement of the tip of the blade support arm. The rack teeth are curved and extended so as to be held, and the rack teeth are slidably engaged with the engaging teeth.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, FIG. 1 is an explanatory side view showing an embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II of FIG. 1, FIG. 3 is an operation explanatory view of the present invention, and FIG. FIG. 8 is a comparison curve diagram showing a relationship between a movement error of the rack and the curvature of the rack teeth.
[0010]
In FIG. 1, reference numeral 10 denotes a spindle, and 11 denotes a blade support arm attached to the tip end side (left end side in FIG. 1) of the spindle 10. 1 is supported on the spindle 10 via a fulcrum shaft 12 so as to be able to swing up and down in FIG. A pair of weights 14 a and 14 b are attached to the center of the swing of the blade support arm 11 via a bracket 13. The weights 14a, 14b have the same mass W, W, and are opposed to each other on a line orthogonal to the swing center O of the blade support arm 11 and with the swing center O interposed therebetween.
[0011]
The tip of the blade support arm 11 projects forward (to the left in FIG. 1) from the spindle 10, and a blade 16 is attached to the projection via a holder 15. An engagement pin 17 parallel to the fulcrum shaft 12 is rotatably attached to a rear portion (right portion in FIG. 1) of the blade support arm 11. The engagement pin 17 has both ends protruding from both side surfaces of the blade support arm 11, and forms arcuate engagement teeth (rack teeth) 17 a on the protruding end surface.
[0012]
A draw bar 20 to be moved in the axial direction is fitted to the inner part of the spindle 10, that is, the axis of the spindle 10 located behind the blade support arm 11, and an engaging body 21 is attached to the front end of the draw bar 20. The engaging body 21 has two plate members facing each other, and has a rack tooth 21a which is curved in an arc shape and is inclined forward and downward on the facing side, and the rack tooth 21a is formed as shown in FIG. Is slidably engaged with the engaging tooth 17a of the engaging pin 17 thus formed. As shown in FIG. 5, the rack teeth 21a have a curved form having the characteristic of a correction curve G2 that is symmetric with respect to the above-described error curve G1. The pressure angle between the engaging teeth 17a and the rack teeth 21a is about 20 degrees as shown in FIG.
[0013]
Then, the engagement position of the rack teeth 21a of the engagement body 21 with the engagement teeth 17a of the engagement pin 17 is moved in the front-rear direction by adjusting the movement of the engagement body 21 in the front-rear direction via the draw bar 20, thereby moving the blade The swing angle α about the fulcrum shaft 12 of the support arm 11 is adjusted, and the amount of deviation of the cutting edge of the blade 16 attached to the tip of the blade supporting arm 11 from the spindle axis E in the radial direction, that is, the cutting edge radius D1 Adjust
[0014]
Here, the front side mass of the blade support arm 11 is M1, the rear side mass is M2, the weight of the weight 17 is W, the distance of the masses M1 and M2 to the fulcrum axis O is L1, L2, and the fulcrum of the mass W. Assuming that the radius with respect to the axis center O is R and the inclination angle of the blade support arm 11 is α, the centrifugal forces T1, T2, and T3 acting on M1, M2, and W with respect to the spindle 10 are as follows.
T1 = M1L1sinαW ²
T2 = M2L2 sinαW ²
T3 = WRcosαW ²
Therefore, the present invention provides the following equation: T1 + T3 = T2 + T3
T1 = T2
M1L1 sinαW ² = M2L2 sinαW ²
M1L1 = M2L2 (1)
, M1, L1, M2, and L2 are set so that the equation (1) holds, and the upper centrifugal force (sum of T1 and T3) and the lower centrifugal force (sum of T2 and T3) of the spindle 10 are set. Are equal.
[0015]
The rotational moments S1, S2, and S3 with respect to the fulcrum shaft center O are given by the following equations.
^{S1 = T1L1cosα = M1L1 2 W 2} sinαcosα
^{S2 = T2L2cosα = M2L2 2 W 2} sinαcosα
S3 = T3R sin α = WR ² W ² sin α cos α
Therefore, the present invention provides the following equation: S1 + S2 = S3 + S3 = 2S3
^{M1L1 2 W 2 sinαcosα + M2L2 2} W 2 sinαcosα = 2WR 2 W 2 sinαcosα
M1L1 ² = M2L2 ² = 2WR ² (2)
, M1, L1, M2, L2, W, and R are set so that the equation (2) holds, and the clockwise rotation moment (S1, S2) and the counterclockwise rotation moment (S3) with respect to the fulcrum axis center O are set. , S3).
[0016]
According to the present invention, the rack teeth 21 of the engagement body 21 may be replaced with long holes or grooves, and these may be slidably fitted to the shaft end of the engagement pin 17.
[0017]
【The invention's effect】
As apparent from the above description, the invention according to claim 1 is provided with an engaging pin at the rear of a blade support arm that is swingably supported by a spindle, and is moved in the axial direction by a draw bar to slide with the engaging pin. An engaging body that movably engages and swingably adjusts the blade support arm via the engaging pin is provided, and a sliding surface of the engaging body with the engaging pin is used to reciprocate the draw bar and move the blade supporting arm. Since the curved surface maintains the movement of the tip in the radial direction in a proportional relationship, no error occurs between the command value and the actual movement value of the blade, and the machining accuracy is increased.
The invention according to claim 2 is characterized in that a weight is provided at the swing center of the blade support arm, and the rotation moment of the spindle rotation by the weight is reversed with respect to the rotation moment of the blade support arm generated during the rotation of the spindle. Since the directions are substantially equal to each other, the rotational moment of the blade support arm generated when the spindle rotates at an arbitrary swing angle of the blade support arm is balanced, and high-speed rotation is possible.
In the invention according to claim 3, the engaging pin and the engaging body are slidably meshed with the rack teeth, and the rack teeth of the engaging body hold the reciprocating movement of the draw bar and the radial movement of the blade in a proportional relationship. As a result, the engagement force between the engagement pin and the engagement body is increased, and play due to wear of the sliding portion is reduced, so that the operation of the blade support arm is stabilized for a long time.
[Brief description of the drawings]
FIG. 1 is an explanatory side view showing an embodiment of the present invention.
FIG. 2 is a sectional view taken along line II-II of FIG.
FIG. 3 is a diagram illustrating the operation of the present invention.
FIG. 4 is a comparison curve diagram showing a relationship between a movement error of a blade with respect to a movement amount of an engagement body and a curvature of a rack tooth.
FIG. 5 is an explanatory side view showing a conventional example.
FIG. 6 is a sectional view taken along line VI-VI of FIG. 5;
FIG. 7 is an explanatory diagram of a conventional operation.
[Explanation of symbols]
Reference Signs List 10 spindle 11 blade support arm 12 fulcrum shaft 13 brackets 14a, 14b weight 15 holder 16 blade 17 engaging pin 17a engaging teeth (rack teeth)
20 Drawbar 21 Engagement body 21a Rack teeth

Claims (3)

A blade support arm (11) extending in the axial direction via a fulcrum shaft (12) orthogonal to the spindle (10) is provided at a tip end side of the spindle (10) in a swingable and non-rotatable manner. (11) An engaging pin (17) parallel to the fulcrum shaft (12) is provided at a rear portion, and a draw bar (20) that is moved in the axial direction is provided at an inner deep portion of the spindle (10). ) Is provided with an engagement body (21) slidably engaged with the engagement pin (17), and a sliding surface of the engagement body (21) with the engagement pin (17) is provided on the drawbar (20). A tool biasing device for a machine tool, characterized in that the reciprocating movement of the tool support arm (11) and the radial movement of the tip of the tool support arm (11) have a curved surface that holds the proportional relationship. Weights (14a) which are opposed to the center of the swing of the blade support arm (11) and intersect with the center of the swing (O) of the blade support arm (11) with the swing center (O) interposed therebetween. , 14b), and the rotational moment (S3) of the weight (14a, 14b) when the spindle (10) rotates is converted to the rotational moment (S1, S2) of the blade support arm (11) generated when the spindle (10) rotates. 2. The blade biasing device for a machine tool according to claim 1, wherein the device is set to be opposite to and substantially equal to the blade. An engaging pin (17) parallel to the fulcrum shaft (12) is rotatably provided at the rear of the blade support arm (11), and a tooth-shaped engaging tooth (17a) is provided on an end surface of the engaging pin (17). A rack tooth (21a) extending in the direction of movement of the drawbar (20) is formed on an engaging body (21) provided on the drawbar (20) at the pitch, and the rack tooth (21a) is connected to the drawbar. The reciprocating movement of (20) and the radial movement of the tip of the blade support arm (11) are curved and extended so as to maintain a proportional relationship, and the rack teeth (21a) are connected to the engaging teeth (17a). 3. The blade biasing device for a machine tool according to claim 1, wherein the device is slidably engaged.

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