FR2765509A1 - TOOL HOLDER, ESPECIALLY FOR A MACHINE TOOL - Google Patents

Abstract

The present invention relates to tool holders used to secure a tool to a machine tool spindle. The tool holder 10 according to the invention is essentially characterized in that it comprises a shank portion 11, a clamping flange 12, a tool fixing portion 13, a groove 121 formed in the outer circumference of the flange 12, a pair of diametrically opposed keyways 122, 1 2 3 formed in flange 12, these keyways 122, 123 having different radial depths, a notch 134 formed in flange 12 near the shallower one 122 of two keyways 122, 123, and a recessed portion 14, to reduce the rotational imbalance of the flange 12, formed radially inward at a portion of the groove 121 to a predetermined depth and over a predetermined angular range 62 on the side of the flange 12 opposite the notch 134 with respect to a diametral line L passing through the center of the shallowest keyway 122.

Description

The present invention relates to a tool holder used to fix a tool

  to a machine tool spindle, and more particularly a tool holder which

  can guarantee a rotational balance in the event of rotation at high speed.

  A conventional tool holder will be described with reference to Figures 3 and 4. Figure 3 is a side view of a tool holder conforming to ISO, and Figure 4 is a plan view of the tool holder seen in the direction of arrow B

in figure 3.

  In Figures 3 and 4, the tool holder 30 has a tapered shank portion 31 intended to be inserted into a spindle of a machine tool not shown, a clamping flange 32 formed at the end of larger diameter of the tapered shank portion 31, and a tubular tool attachment portion 33, which extends from an end surface of the flange 32, opposite the tapered shank portion 31. The tool attachment portion 33 extends in a direction away from the tapered tail portion 31 so that the axis of the portion 33

  tool attachment coincides with the axis of the tapered shank portion 31.

  On the outer circumference of the clamping flange 32 is formed a groove 321, for example a V-shaped groove, of a predetermined depth. During a tool change operation, clamping fingers of a tool change apparatus engage the groove 321. In addition, a pair of keyways or guide key grooves 322 and 323 generally longitudinal essentially diametrically opposite are formed respectively in the flange 32. The keyway 322 has a radial depth less than the radial depth of the keyway 323. In addition, near the keyway 322, a notch or generally V-shaped groove 324 is formed in the flange 32. The notch or groove 324 is used to maintain a predetermined rotational phase of a tool carried by the tool holder when the tool is inserted together with the holder -tool in a

tool pot from a tool store.

  In such a conventional tool holder, as the key grooves 322 and 323 formed in the flange 32 have different depths and the notch 324 is formed near the key groove 322, the flange 32 has an asymmetrical shape by relative to its axis, which causes a

mass imbalance.

  Therefore, when such a tool holder is rotated at high speed (equal to or greater than 10,000 rpm) during a precision finishing operation, there is a rotational imbalance in the flange due to the effect of eccentric forces generated during high speed rotation, which results in the tool holder carrying the tool

  causes vibrations of low amplitude, which generate a chatter.

  The present invention has been implemented to at least partially solve the aforementioned problems, and the invention aims to provide a tool holder which facilitates the adjustment of the rotational imbalance of

  the flange while preserving compliance with the ISO standard.

  According to the present invention, there is provided a tool holder comprising a shank portion intended to cooperate with a machine tool; a clamp formed at one end of said tail portion; a tool fixing portion which extends from the end surface of said flange, opposite to said tail portion, said tool fixing portion extending in the direction away from said tail portion, in alignment with the axis of said tail portion; a groove formed in the outer circumference of said flange and having a predetermined depth; a pair of substantially diametrically opposite keyways formed in said flange, said keyways having different radial depths; and a notch formed in said flange near the shallowest of said keyways, characterized in that it further comprises a recessed portion to reduce the rotational imbalance of said flange, said recessed portion being formed radially inwards at a portion of said groove to a predetermined depth and over a predetermined angular range, on the side of the flange opposite to said notch with respect to a diametrical line which passes through the center of said

shallower keyway.

  Preferably, the depth and the angular range of the hollowed out portion

  are determined according to the radius of the flange.

  Preferably, the hollowed out portion is machined using a shank cutter. In the present invention, the mass balance of the flange in the circumferential direction is obtained by forming a recessed portion in the bottom surface of the groove, up to a predetermined depth and over a predetermined angular range on the side. opposite the notch with respect to a diametrical line which passes through the center of the shallower keyway. Consequently, the rotational imbalance of the flange is eliminated, this imbalance being generated due to the difference in depth between the pair of keyways and the formation of the notch. Therefore, it is possible to provide a tool holder which does not cause chattering, even

  when rotating at high speed.

  In addition, in the present invention, since the recessed portion, to eliminate the rotational imbalance, is formed in the surface of the bottom of the groove of the flange, the. rotational imbalance can easily be

  essentially eliminated while preserving compliance with the IS0 standard.

  Various other objectives, features and many associated advantages of the present invention will be readily appreciated as it becomes

  better understood on reading the following detailed description of the mode of

  preferred embodiment, given with reference to the appended drawings in which: FIG. 1 is a side view of a tool holder according to an embodiment of the present invention; Figure 2 is a sectional view along line A-A of Figure 1; Figure 3 is a side view of a conventional tool holder; and FIG. 4 is a plan view of the conventional tool holder according to the

  direction of arrow B in figure 3.

  An embodiment of the present invention will be described in

reference to the accompanying drawings.

  Figure 1 is a side view of a tool holder according to an embodiment of the present invention, and Figure 2 is a sectional view along

line A-A in Figure 1.

  As shown in Figures 1 and 2, a tool holder 10 according to the present embodiment has a tapered shank portion 11 intended to be inserted into a spindle of a machine tool not shown, a clamping flange 12 formed at the level of the larger diameter end of the tapered shank portion 11, and a tool attachment portion 13, which in this case is tubular, which extends from the end surface of the opposite flange 12 to the tapered shank portion 11. The tool attachment portion 13 extends in the direction away from the tapered shank portion 11 so that the axis of the tool attachment portion 13 coincides with the axis of the tapered tail portion 11. On the outer circumference of the clamping flange 12 is formed a groove 121 of the predetermined depth. In the illustrated embodiment, the groove comprises a circumferential base region 124 and inclined walls 125, 126. In other embodiments, the groove can generally have a V shape, a U shape or any other configuration. that those skilled in the art will deem appropriate. During a tool changing operation, the clamping fingers of a tool changing apparatus engage the groove 121. In addition, keyways or guideway grooves 122 and 123 generally longitudinal, essentially diametrically opposite, are respectively formed in the flange 12. The keyway 122 has a radial depth less than the radial depth of the keyway 123. In addition, near the keyway 122, a notch or groove 134 generally longitudinal V-shaped is formed in the flange 12. The notch or groove 134 is used to maintain a predetermined rotational phase of a tool carried by the tool holder when the tool is inserted, together with the holder tool in a jar

tools from a tool store.

  In addition, a recessed portion 14, to reduce or eliminate the rotational imbalance of the flange 12, is formed in the base region of the groove 121 to a predetermined depth d on the side opposite the notch 134 relative to a diametrical line L which passes through the center of the shallower keyway 122. The hollowed-out portion 14 is formed on an angular range 02 starting at a position separated from the line

diametral L of an angle 61.

  The hollowed out portion can be easily machined using a milling cutter

  tail or similar tool while maintaining ISO standard compliance.

  For example, in the case of a tool holder according to the number of the ISO standard of the ISO standard, the diameter of the flange 12 is 97.50 mm. In order to adjust the rotational imbalance of the flange 12, the angle 01 was set at 23, the angle 02 was set at 40, and the depth was set at 4.8 mm. Thanks to the training of

  the recess, the rotational imbalance of the flange has been eliminated.

  In addition, in the case of a tool holder according to the ISO standard number 40 of the ISO standard, the diameter of the flange 12 is 63.55 mm. In order to adjust the rotational imbalance of the flange 12, the angle 01 was set at 24, the angle 02 was set at 60, and the depth was set at 3.5 mm. Thanks to the training of

  the recess, the rotational imbalance of the flange has been eliminated.

  In the embodiment described above, the mass balance of the flange in the circumferential direction is obtained by the formation of a hollowed-out portion 14 in the surface of the bottom of the groove 121 to a predetermined depth d on the side opposite to the notch 134 with respect to a diametrical line L which passes through the center of the keyway 122 which is shallower, the hollowed-out portion 14 being formed over a predetermined angular range 02 starting at the position separated from the diametral line L of an angle el. Consequently, the rotational imbalance of the flange 12 is reduced or eliminated, this imbalance being generated due to the difference in depth between the pair of keyways 122 and 123 and the formation of the notch or groove 134. By Therefore, it is possible to provide a tool holder that does not cause chattering, even in the event of

  rotation at high speed, which allows precise machining of the part.

  Obviously, many modifications and variations of the present invention are possible in light of the above teachings. he

  must therefore be understood that, within the scope of the appended claims, the

  present invention may be practiced other than as described

specifically here.

  In this specification, except where the context requires, "longitudinal" refers to a direction generally parallel to the axis of the tail portion, and "longitudinally" should be interpreted accordingly; "radial" refers to a radial direction to a line that includes the axis of the tail portion and "radially" should be interpreted accordingly; "circumference" refers to an arc or portion of an arc described on a surface by a point on a radius when said radius is rotated around a line which includes said axis of the tail portion, and "circumferential" and " circumferentially "should be interpreted correspondingly, and" diametrically opposite "refers to the respective positions at which a diameter crosses a circumference.

Claims (4)

  1. Tool holder (10) comprising a tail portion (11) intended to cooperate with a machine tool; a clamp (12) formed at one end of said tail portion (11); a tool attachment portion (13) which extends from the end surface of said flange (12), opposite said shank portion (11), said tool attachment portion (13) extending in the direction away from said tail portion (11) in alignment with the axis of said tail portion (11); a groove (121) formed in the outer circumference of said flange (12) and having a predetermined depth; a pair of substantially diametrically opposite keyways (122, 123) formed in said flange (12), said keyways (122, 123) having different radial depths; and a notch (134) formed in said flange (12) near the shallowest (122) of said keyways (122, 123), characterized in that it further comprises a recessed portion (14) to reduce the rotational imbalance of said flange (12), said recessed portion being formed radially inwards at a portion of said groove (121) to a predetermined depth and over a predetermined angular range (02) on the side of the flange (12) opposite said notch (134) with respect to a diametrical line (L) passing through the center of   said shallow keyway (122).   2. Tool holder according to claim 1, characterized in that the depth and the angular range of said hollowed portion (14) are determined   as a function of the radius of said flange (12).   3. Tool holder according to one of claims 1 and 2, characterized in that   that the hollowed out portion (14) is machined using a shank cutter.   4. Tool holder according to one of the preceding claims, characterized by   the fact that the groove (121) comprises a circumferential base portion (124) and opposite walls inclined (125, 126) relative to the radial direction of   the flange and extending respectively from said base portion.