CHUCK DEVICE

Abstract

Provided is a chuck device that allows appropriate and easy setting of a discharging direction of working fluid. A chuck device configured to be attached to a spindle of a machine tool for gripping a cutting tool, in which inside the chuck device, there are provided a passage in which a working fluid flows and a discharge opening provided at a leading end opening of the passage through which the working fluid is discharged toward to the cutting tool. A discharging direction of the working fluid from the discharge opening is set opposite to a rotational direction of the cutting tool and set with a tilt of an angle calculated by a mathematical formula to a tangential direction of a rotation trajectory of the center of the discharge opening relative to a direction of an axis of the cutting tool.

Claims

1. A chuck device configured to be attached to a spindle of a machine tool for gripping a cutting tool, wherein: inside the chuck device, there are provided a passage in which a working fluid flows and a discharge opening provided at a leading end opening of the passage through which the working fluid is discharged toward to the cutting tool; and a discharging direction of the working fluid from the discharge opening is set opposite to a rotational direction of the cutting tool and set with a tilt of an angle calculated by a following formula to a tangential direction of a rotation trajectory of the center of the discharge opening relative to a direction of an axis of the cutting tool;
=sin.sup.1((nDc)/(1210.sup.5{square root over (5P)}))[Formula 1] n: rotational speed of chuck device (min-1) Dc: diameter of virtual circle defined by rotation trajectory of center of discharge opening (mm) P: working fluid pressure at discharge opening (MPa) : circular constant

2. The chuck device of claim 1, wherein the discharging direction is set to be directed toward the axis of the cutting tool.

3. The chuck device of claim 1, wherein the angle is set to from 0.9 degree to 55.9 degrees when a circumferential speed V at the discharge opening due to the rotation of the chuck device calculated by a following formula ranges from 1.9 m/s to 64.1 m/s.
V=nDc)/(6010.sup.3)[m/s][Formula 2] n: rotational speed of chuck device (min-1) Dc: diameter of virtual circle defined by rotation trajectory of center of discharge opening (mm) : circular constant

4. The chuck device of claim 2, wherein the angle is set to from 0.9 degree to 55.9 degrees when a circumferential speed V at the discharge opening due to the rotation of the chuck device calculated by a following formula ranges from 1.9 m/s to 64.1 m/s.
V=(nDc)/(6010.sup.3)[m/s][Formula 2] n: rotational speed of chuck device (min-1) Dc: diameter of virtual circle defined by rotation trajectory of center of discharge opening (mm) : circular constant

Description

BRIEF DESCRIPTION OF DRAWINGS

[0025] FIG. 1 is a side view of a chuck device,

[0026] FIG. 2 is a perspective view for explaining a discharging direction of the chuck device,

[0027] FIG. 3 is a view for explaining a position of a discharge opening in the chuck device,

[0028] FIG. 4 is a view for explaining an angle for setting the discharging direction of working fluid,

[0029] FIG. 5 is a view for explaining an angle 2 for discharging the working fluid toward an axis of a cutting tool,

[0030] FIG. 6 is a view showing a passage and a discharge opening in a further embodiment, and

[0031] FIG. 7 is a view showing a passage and a discharge opening in a further embodiment.

DESCRIPTION OF EMBODIMENTS

[0032] Next, embodiments of a chuck device relating to the present invention will be explained with reference to the accompanying drawings.

[0033] A chuck device A shown in FIG. 1 is mounted on a spindle of a machine tool in such a manner that the axis of the spindle and the axis Q of the chuck device A are coaxial (in agreement). Further, to this chuck device A, a cutting tool B (see FIG. 2) will be inserted from the right side in FIG. 1 and gripped coaxially with the axis Q. With this, the axis of the spindle and the axis of the cutting tool B will be brought into agreement.

[0034] A body 1 of the chuck device A includes a chuck body 1a, a chuck cylinder 1b and a shank 1c. The chuck cylinder 1b is formed on the leading end side of the chuck body 1a. The shank 1c is formed on the rear end side of the chuck body 1a and attached to the spindle of the machine tool.

[0035] In the chuck cylinder 1b, there is formed a hole portion (not shown) for griping the cutting tool B (see FIG. 2) along the direction of the axis Q. As shown in FIG. 2, inside the chuck cylinder 1b, there is provided a coolant discharge passage 3b (an example of a passage) through which coolant (an example of a working fluid) flows. This coolant discharge passage 3b extends in the direction of the axis Q and is communicated with a coolant supplying passage (not shown) provided separately in the chuck cylinder 1b. The coolant supplying passage is e.g. a passage formed through the inside of the body 1 along the axial direction of the body 1. The coolant discharge passage 3b is provided in a plurality along the circumferential direction of the body 1 (two coolant discharge passages 3b are provided in the instant embodiment). At the leading end of the body 1 in each coolant discharge passage 3b, a discharge opening 3a is formed. Namely, at a leading end face 1d of the body 1 (chuck cylinder 1b), there are provided a plurality of discharge openings 3a opened in a circular shape (two discharge openings 3a in the instant embodiment). As the plurality of discharge openings 3a are arranged equidistantly in the circumferential direction of the body 1, coolant can be sprayed uniformly around the cutting tool B.

[0036] Here, for reliable supplying of the coolant to the cutting tool B, the discharging directions of the coolant need to be set appropriately at the discharge openings 3a provided at the leading end of the body 1. When the coolant is to be discharged from the discharge openings 3a of the chuck device A toward the cutting tool B, the discharged coolant will be subjected to the greater influence from the rotational force of the chuck device A, the higher this rotational speed of the chuck device A. For this reason, the discharged coolant will be scattered about in directions away from the axis Q of the cutting tool B. Then, as shown in FIG. 2, the discharging directions of the coolant are set to directions opposite to the rotational direction Rd of the cutting tool B (chuck device A). Specifically, as shown in FIG. 2, the discharging direction of the coolant is set such that a circumferential speed Vy will be effective in the direction opposite to the rotational direction Rd relative to a circumferential speed V in the rotational direction Rd at the discharge opening 3a. And, the discharging direction of the coolant is set such that the direction is set with a tilt of a predetermined angle to a tangential direction (direction of the circumferential speed Vy) of a rotation trajectory (virtual circle 5) of the center of the discharge opening 3a at the time of rotation of the chuck device A on the basis of the direction of the axis Q of the cutting tool B.

[0037] In this way, the discharging direction of the coolant is set opposite to the rotational direction Rd of the cutting tool B (chuck device A) and with appropriate setting of the tilt angle relative to the direction of the axis Q of the cutting tool, the influence of the rotational force of the chuck device A to the discharged coolant can be offset. As a result, even when the chuck device A is rotated at a high speed, scattering of the coolant discharged from the discharge openings 3a to the radial outer side of the cutting tool B can be suppressed. Here, a formula for obtaining the angle for suppressing such scattering of coolant will be considered.

[0038] An average flow rate (velocity) Vav (m/x) of coolant flowing through the inside of the chuck device A can be calculated from Formula 3 below with using a coolant pressure (MPa) at the discharge opening 3a.

V.sub.av={square root over (2P10.sup.3)}[Formula 3]

[0039] The circumferential speed V (m/s) at the discharge opening 3a due to the rotation of the chuck device A can be obtained by Formula 4 below from a rotational speed: n (min.sup.1) of the chuck device A, a diameter: Dc (mm) of a virtual circle S formed by the rotation trajectory of the center of the discharge opening 3a (see FIG. 3) and the circular constant .

V=(nDc)/(6010.sup.3)[Formula 4]

[0040] Here, an angle 3 (see FIG. 2) for discharging coolant from the discharge opening 3a toward the cutting tool B can be obtained from Formula 5 below with using an angle (see FIG. 2 and FIG. 4) set for tilting to the opposite side to the rotational direction Rd in the tangential direction to the rotation trajectory of the discharge opening 3a relative to the direction of the axis Q and an angle 2 (see FIG. 2 and FIG. 5) set for tilting to the direction (direction of Vx) from the discharge opening 3a toward the axis Q relative to the direction of the axis Q.

3=tan.sup.1({square root over (tan.sup.2+tan.sup.22)})[Formula 5]

[0041] On the other hand, a velocity vector of coolant discharged from the discharge opening 3a can be decomposed into a velocity vector Vx from the discharge opening 3a toward the axis Q of the cutting tool B, a velocity vector Vy in the direction opposite to the velocity vector V in the tangential direction of the rotation trajectory (virtual circle S) and a velocity vector Vz in the direction of the axis Q of the cutting tool B; and the velocities Vx, Vy, Vz can be obtained respectively by following Formulae 6-8 using the angles , 2 and 3.

V.sub.x=Vavcos 3tan 2[Formula 6]

Vy=Vavcos 3tan [Formula 7]

Vz=Vavcos 3[Formula 8]

[0042] If the velocity vector V in the rotational direction Rd and the velocity vector Vy in the opposite direction to the rotational direction Rd are equal to each other and Vx>0, then, the velocity vector Vxy in the discharging direction includes only the velocity vector Vx, so the coolant is discharged toward the axis Q of the cutting tool B.

[0043] The angle 2 set for discharging coolant toward the center of the cutting edge of the cutting tool B varies according to the length of the cutting tool B protruding from the chuck device A. However, since the cutting tool B needs to have an appropriate length for machining a work or the like, the angle 2 will be set normally to about 15 degrees at most. If the angle 2 is 15 degrees or less, then, it may be taken as cos 03 cos and its error range will be confined within 4% or less.

[0044] Then, on the premise of cos 3cos and ignoring the above error, with substitution thereof into the above-described Formula 7 for calculating the speed (circumferential speed) Vy in the reverse rotational direction, Formula 9 below is obtained.

Vy=Vavcos tan =Vavsin [Formula 9]

[0045] In case the circumferential speed V in the rotational direction Rd and the circumferential speed Vy in the reverse rotational direction are equal, by substituting the circumferential speed V of the above Formula 4 into the Formula 9 above, Formula 10 below can be derived. By substituting Vav (average flow rate of coolant flowing inside the chuck device A) of Formula 3 above into Formula 10, Formula 11 can be derived and then from this Formula 11, Formula 12 for obtaining the angle can be derived.

(nDc)/(6010.sup.3)=Vavsin [Formula 10]

(nDc)/(6010.sup.3)={square root over (2P10.sup.3)}sin [Formula 11]

=sin.sup.1((nDc)/(1210.sup.5{square root over (5P)}))[Formula 12]

[0046] n: rotational speed of chuck device (min.sup.1)

[0047] Dc: diameter of virtual circle defined by rotation trajectory of center of discharge opening (mm)

[0048] P: working fluid pressure at discharge opening (MPa)

[0049] : circular constant

[0050] Namely, when setting the discharging direction of coolant in the chuck device A, using an angle calculated by the above Formula 12 results in discharging of the coolant from the discharge opening 3a in the direction of the axis Q of the cutting tool B.

[0051] Moreover, with appropriate setting of the angle 2 for causing the discharging direction of coolant to be directed toward the axis Q of the cutting tool B, the coolant discharged from the discharge opening 3a can be readily supplied toward the cutting tool B.

Example 1

[0052] The cutter diameter D of the cutting tool B to be gripped by the chuck device A was varied between 3 mm or less to 32 mm. The rotational speed of the chuck device A was set in correspondence with cutting speed range from 100 to 500 m/min. However, if the cutter diameter D becomes less than 3 mm, a special machine tool will be needed which can cope with high speeds in order to satisfy the cutting speed ranging from 100 to 500 m/min. Thus, in the case of the cutter diameter less than 3 mm, the rotational speed of the chuck A was set to the range of from 10,000 to 50,000 min.sup.1 possible with a standard machine tool.

[0053] In correspondence with the cutter diameter D, the range of the diameter Dc of the virtual circle S formed by the rotation trajectory of the center of the discharge opening 3a and the range of the rotational speed n of the chuck device A were set. The coolant pressure (working fluid pressure) P at the discharge opening 3a was maintained from 3 to 7 MPa. Ranges of the circumferential speeds V and the angle calculated based on these are shown in Table 1 below

TABLE-US-00001 TABLE 1 virtual circle diameter discharge Dc at opening cutter discharge rotational circumferential coolant diameter opening speed n speed V pressure D [mm] [mm] [min.sup.1] [m/s] [MPa] [degrees] 3 or less 6~16 10,000~50,000 3.1~41.9 3~7 1.5~32.7 4 8~16 8,000~40,000 3.3~33.5 3~7 1.6~25.6 6 10~16 5,300~27,000 2.8~22.6 3~7 1.3~17.0 8 12~18 4,000~20,000 2.5~18.8 3~7 1.2~14.1 10 14~20 3,200~16,000 2.3~16.7 3~7 1.1~12.5 12 16~22 2,700~13,000 2.3~15.0 3~7 1.1~11.1 16 20~26 2,000~10,000 2.1~13.6 3~7 1.0~10.1 20 24~30 1,600~8,000 2.0~12.6 3~7 1.0~9.3 25 29~35 1,300~6,400 2.0~11.7 3~7 1.0~8.7 32 36~42 1,000~5,000 1.9~11.0 3~7 0.9~8.2

Example 2

[0054] There is disclosed an example using a special machine tool capable of rotating the chuck device A at a high speed without reducing the rotational speed of the chuck device A even when the cutter diameter D is increased. The cutter diameter D was varied from 3 mm or less to 32 mm and in correspondence with such cutter diameter D, the range of the diameter Dc of the virtual circle S formed by the rotation trajectory of the center of the discharge opening 3a was set. The rotational speed n of the chuck device A was maintained in the range from 25,000 to 35,000 min.sup.1. The coolant pressure (working fluid pressure) P at the discharge opening 3a was maintained from 3 to 7 MPa. Ranges of the circumferential speeds V and the angle calculated based on these are shown in Table 2 below

TABLE-US-00002 TABLE 2 virtual circle diameter discharge Dc at opening cutter discharge rotational circumferential coolant diameter D opening speed n speed V pressure [mm] [mm] [min.sup.1] [m/s] [MPa] [degrees] 3 or less 6~16 25,000~35,000 7.9~29.3 3~7 3.8~22.2 4 8~16 25,000~35,000 10.5~29.3 3~7 5.1~22.2 6 10~16 25,000~35,000 13.1~29.3 3~7 6.4~22.2 8 12~18 25,000~35,000 15.7~33.0 3~7 7.6~25.2 10 14~20 25,000~35,000 18.3~36.6 3~7 8.9~28.2 12 16~22 25,000~35,000 20.9~40.3 3~7 10.2~31.4 16 20~26 25,000~35,000 26.2~47.6 3~7 12.8~38.0 20 24~30 25,000~35,000 31.4~55.0 3~7 15.4~45.2 25 29~35 25,000~35,000 37.9~64.1 3~7 18.7~55.9

Other Embodiments

[0055] (1) The chuck device relating to the present invention can be embodied irrespectively of its type, with any chuck device attached to a spindle of a machine tool for gripping a cutting tool.

[0056] (2) The disposing positon of the coolant discharge opening 3a for the coolant in the chuck device A is not limited to the leading end face 1d of the chuck cylinder 1b, but may be in a nut member or a colette in correspondence with a manner of gripping the cutting tool B or in a cover member to be connected to a leading end face 1d of the chuck cylinder 1b or to the colette or the like. In this way, the discharge opening 3a for the coolant is not limited by the above-described embodiments, but can be provided as desired within a range capable of achieving the object of the present invention.

[0057] (3) In the foregoing embodiment, there was disclosed an example in which the coolant discharge passage 3b as a whole is tilted relative to the axis Q. Instead of this, as shown in FIG. 6, of the coolant discharge passage 3b, a partial area 3b2 thereof continuous with the discharge opening 3a may be tilted relative to the axis Q so as to be aligned with the discharging direction based on the angle . In FIG. 6, the partial area 3b2 has a length set to be three times as long as the diameter d of the discharge opening 3a. In this way, for the purpose of causing the coolant to be discharged along the passage of discharging direction based on the angle , it is preferred that the passage length of the partial area 3b2 be equal to or longer than three times the diameter d of the discharge opening 3a. As shown in FIG. 7, it is also possible to arrange such that of the coolant discharge passage 3b, a flow passage of a partial area 3b3 thereof continuous with the discharge opening 3a be formed narrower than the passage of the other area, so as to cause the coolant to be discharged along the discharging direction based on the angle . In FIG. 7, the partial area 3b3 is formed progressively narrower as it approaches the discharge opening 3a.

[0058] In this way, by forming a partial area 3b2, 3b3 continuous with the discharge opening 3a of the coolant discharge passage 3b to be aligned with the discharging direction based on the angle , the coolant can be discharged from the discharge opening 3a toward the cutting tool B. Further, if only the partial area 3b2, 3b3 of the coolant discharge passage 3b is formed along the discharging direction of the coolant, the other area of the coolant discharge passage 3b than the partial area 3b2, 3b3 can be formed e.g. along the axial direction of the chuck device A. With this, even when the angle for setting the discharging direction of the coolant is large, it is still possible to reduce the occupying area of the coolant discharge passage 3b in the circumferential direction of the chuck device

A. As a result, in the chuck device A, the coolant discharge passage 3b can be disposed easily.

INDUSTRIAL APPLICABILITY

[0059] The present invention can be used for a wide variety of chuck devices configured to supply working fluid to a tool.

REFERENCE SIGNS LIST

[0060] 1: body [0061] 1b: chuck cylinder [0062] 1d: leading end face [0063] 3a: discharge opening [0064] 3b: coolant discharge passage (passage) [0065] 3b2: partial area [0066] 3b3: partial area [0067] A: chuck device [0068] B: cutting tool [0069] D: cutter diameter [0070] Dc: diameter of virtual circle formed by rotation trajectory of center of discharge opening [0071] Rd: rotational direction [0072] Q: axis [0073] S: virtual circle [0074] : angle for tilting discharging direction of working fluid to tangential direction of rotational direction [0075] 2: angle for tilting discharging direction of working fluid toward axis [0076] 3: discharging angle of working fluid based on axial direction