CN114433962A

CN114433962A - Vibration damping mechanism of gear processing machine tool

Info

Publication number: CN114433962A
Application number: CN202210245840.9A
Authority: CN
Inventors: 姜辉; 张安禄; 马鑫; 徐西旺
Original assignee: Shandong Runtong Gear Group Co ltd
Current assignee: Shandong Runtong Gear Group Co ltd
Priority date: 2022-03-14
Filing date: 2022-03-14
Publication date: 2022-05-06

Abstract

The invention relates to a vibration damping mechanism of a gear processing machine tool, which enables a main shaft to reciprocate through a crank mechanism, and the vibration damping mechanism comprises: a first balance shaft and a second balance shaft arranged in parallel to a crank shaft of the crank mechanism, the first balance shaft and the second balance shaft rotating in synchronization with the crank shaft at the same speed as that of the crank shaft, the first balance shaft rotating in a direction opposite to a rotating direction of the crank shaft, the second balance shaft rotating in the same direction as the rotating direction of the crank shaft; a main balance weight detachably coupled to the crank shaft so as to reduce vibration in an axial direction of the main shaft; and a secondary balance weight detachably connected to the first and second balance shafts so as to reduce vibration in a direction perpendicular to the axial direction of the main shaft, the primary and secondary balance weights being selected based on a stroke width of the main shaft and based on a helix angle to be molded in the gear blank. The invention can effectively reduce the mechanical vibration during gear processing.

Description

Vibration damping mechanism of gear processing machine tool

Technical Field

The invention relates to the technical field of gear machining, in particular to a vibration reduction mechanism of a gear machining machine tool.

Background

Gear cutting machines, such as gear shaping machines, are provided as conventional machines for performing gear cutting on gear blanks using rotating tools. When this type of gear processing machine is used, a workpiece (gear blank) is formed into a desired gear shape by intermeshing a rotary tool (rotary tool) with a rotary workpiece and then reciprocating the tool in the axial direction of the workpiece.

The reciprocating motion of the tool is achieved by moving a spindle connected to the tool in its axial direction by moving a crank mechanism. However, such reciprocating motion of the spindle generates vibration in the machine tool due to an internal force of the spindle or the like. The vibration may adversely affect the machining accuracy.

Disclosure of Invention

The present invention is directed to solve the above problems and to provide a vibration damping mechanism for a gear cutting machine.

In order to achieve the above object, the present invention provides a vibration damping mechanism of a gear processing machine for reciprocating a spindle by a crank mechanism, the vibration damping mechanism comprising: a first balance shaft and a second balance shaft arranged in parallel to a crank shaft of the crank mechanism, the first balance shaft and the second balance shaft rotating in synchronization with the crank shaft at the same speed as that of the crank shaft, the first balance shaft rotating in a direction opposite to a rotating direction of the crank shaft, the second balance shaft rotating in the same direction as the rotating direction of the crank shaft;

a main balance weight detachably coupled to the crank shaft so as to reduce vibration in an axial direction of the main shaft; and a secondary balance weight detachably connected to the first and second balance shafts so as to reduce vibration in a direction perpendicular to the axial direction of the main shaft, the primary and secondary balance weights being selected based on a stroke width of the main shaft and based on a helix angle to be molded in the gear blank.

According to one aspect of the invention, the primary weight comprises: a front side balance weight having a phase offset by 180 ° from a phase of a main shaft supported eccentrically with respect to a center of the crank shaft; and a rear-side balance weight having a phase offset by 180 ° from the phase of the front-side balance weight so as to solve an imbalance caused by the offset between a position of a center of mass of the main shaft and a position of a center of mass of the front-side balance weight in an axial direction of the crank shaft.

According to an aspect of the present invention, the auxiliary balance weight is disposed at the same position in the axial direction of the crank shaft as the position of the center of mass of the main shaft in the axial direction of the crank shaft.

The vibration reduction mechanism of a gear processing machine of the present invention can surely reduce mechanical vibration by taking into account torsional movement of a main shaft according to a helix angle to be formed in a gear blank when selecting each balance weight.

Drawings

Fig. 1 schematically shows a structural view of a vibration damping mechanism of a gear processing machine according to an embodiment of the present invention;

FIG. 2 schematically shows a cross-sectional view A-A in FIG. 1;

FIG. 3 is a schematic view showing the structure of a vibration damping mechanism of the present invention;

fig. 4 schematically shows a schematic view of the vibration damping structure of the present invention;

fig. 5 schematically shows a top view of the principle of the damping mechanism of the present invention.

Detailed Description

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

The present invention is described in detail below with reference to the drawings and the specific embodiments, which are not repeated herein, but the embodiments of the present invention are not limited to the following embodiments.

As shown in fig. 1-3, the gear cutting machine includes a column 11. The spindle motor 12 is connected to the upper surface of the column 11 using a bracket 13. A gear box 14 is provided so as to be opposite to the spindle motor 12.

Inside the gear case 14, a crank shaft 15,

balance shafts

16 and 17 are rotatably supported so as to be aligned in parallel with each other.

Gears

18, 19 and 20 are provided on the crank shaft 15 and the

balance shafts

16 and 17, respectively. The gear 18 on the crank shaft 15 meshes with the gear 19 on the balance shaft 16, while the gear 19 on the balance shaft 16 meshes with the gear 20 on the balance shaft 17.

Gear 18 and gear 20 are offset from each other in the Y-axis direction. Therefore, the gear 18 and the gear 19 do not interfere with each other even when these

gears

18 and 20 rotate. Further, the gear ratio between each two of the

gears

18, 19, and 20 is set to 1 so that the crank shaft 15 and the

balance shafts

16 and 17 all rotate at the same speed. Specifically, when the crank shaft 15 rotates, the rotation is transmitted to the balance shaft 16, and the rotation of the balance shaft 16 is then transmitted to the balance shaft 17. In this case, the crank shaft 15 and the balance shaft 16 rotate in opposite directions to each other, and the crank shaft 15 and the balance shaft 17 rotate in the same direction. Further, when the crank shaft 15 rotates by the angle θ, the

balance shafts

16 and 17 also each rotate by the angle θ.

A motorized pulley 21 is provided on the output shaft of the spindle motor 12. A pulley 22 is provided on the rear end of the crank shaft 15. A cogged belt 23 is looped around motorized pulley 21 and pulley 22.

A connecting rod 25 is supported on the front end of the crank shaft 15 with a crank pin 24. The crank pin 24 is located offset from the center of the crank shaft 15 by a distance S, i.e., the connecting rod 25 is eccentrically supported with respect to the crank shaft 15. The bottom end of the connecting rod 25 is supported on a not-shown spherical bearing provided on the bottom end of the main shaft 26. The tool T is detachably attached to the front end of the spindle 26.

The main shaft 26 passes through a cylindrical guide member 27, and is supported by an inner circumferential surface of the guide member 27. The spindle 26 supported thereby is able to slide. A groove (not shown) is formed on the inner circumferential surface of the guide member 27 so as to correspond to the helix angle of the helical gear to be formed on the workpiece W. An engagement portion (not shown) formed on the outer circumferential surface of the main shaft 26 is engaged with the groove. Therefore, when the main spindle 26 slides inside the guide member 27, the main spindle 26 performs a twisting (circling) motion corresponding to the helix angle of the helical gear to be formed of the workpiece W.

The rotating table 28 is rotatably supported at a position opposite to the column 11. The workpiece W is detachably attached to the upper surface of the rotating table 28 by an attachment jig, not shown.

The main balancer 41 whose mass is mB2 is detachably attached to the front end side of the crank shaft 15, while the main balancer 42 whose mass is mB1 is detachably attached to the rear end side of the crank shaft 15. The primary weight 41 is substantially semi-circular in shape. The main weight 41 is disposed on the inner side of the connecting rod 25 in the Y-axis direction, and the phase of the main weight 41 is offset by 180 ° from the phase of the crank pin 24. In addition, the primary weight 42 is also substantially semi-circular in shape. The main weight 42 is disposed on the outer side of the pulley 22 in the Y-axis direction, and the phase of the main weight 42 is the same as that of the crank pin 24, that is, the phase of the main weight 42 is offset by 180 ° from that of the main weight 41.

A secondary balance mass 43 of mass mS2 is detachably connected to the front end of the balance shaft 16, while a secondary balance mass 44 of mass mS1 is detachably connected to the rear end of the balance shaft 16. Further, a sub-balance weight 45 of mass mS2 is detachably attached to the front end of the balance shaft 17, while a sub-balance weight 46 of mass mS1 is detachably attached to the rear end of the balance shaft 17. These secondary weights 43-46 are substantially semi-circular in shape. The phases of the

sub-counterbalances

43 and 45 are offset by 180 ° from the phases of the

sub-counterbalances

44 and 46, respectively.

Therefore, in order to cut the workpiece W with the tool T, the spindle motor 12 is rotated, and the rotation of the spindle motor 12 is transmitted via the gear belt 23 so as to rotate the crank shaft 15. Rotation of the crank shaft 15 rotates the connecting rod 25. The rotation of the link 25 reciprocates the main shaft 26 in the Z-axis direction by the stroke width of 2S. In this case, the main shaft 26 slides inside the guide member 27. Therefore, the rotary tool T engaged with the rotating workpiece W reciprocates for a stroke width longer than the surface width of the workpiece W, and the tool T performs a twisting motion corresponding to the helix angle to be possessed by the workpiece. The workpiece W is cut by the cutter T in this manner.

Incidentally, when the crank shaft 15 rotates, the

balance shafts

16 and 17 also rotate. When mrev represents the movable mass for stroke adjustment of the main shaft 26, and M represents a mass equivalent to the reciprocative part, the movement imbalance in the Z-axis direction between the movable mass for stroke adjustment mrev and the mass equivalent to the reciprocative part M is designed to be solved by connecting the main balance mass 41 of mass mB2 and the main balance mass 42 of mass mB 1. Further, although the movement unbalance in the X axis direction between the main balance weight 41 having the mass mB2 and the main balance weight 42 having the mass mB1 is larger than the movable mass mrev for stroke adjustment, the movement unbalance is designed to be solved by connecting the

sub balance weights

43 and 45 and the

sub balance weights

44 and 46, the

sub balance weights

43 and 45 each having the mass mS2, and the

sub balance weights

44 and 46 each having the mass mS 1. Incidentally, the position of the center of mass of the main shaft 26 and the position of the center of mass of the main balancer 41 are offset from each other in the axial direction (Y-axis direction) of the crank shaft 15 by their connecting structures. However, the balance in the axial direction of the crank shaft 15 can be achieved by attaching the main balancer 42 on the side opposite to the side to which the main balancer 41 is attached.

Subsequently, when the weights 41 to 46 are selected, or when the masses mB1, mB2, mS1 and mS2 are set, the forces in the X-axis direction and the Y-axis direction and the torques about the X-axis and the Z-axis need to be balanced, taking into account the torsional movement of the main shaft 26 corresponding to the helix angle to be formed in the workpiece W. In other words, the balancing needs to be achieved under the condition that the mass M equivalent to the reciprocative part must be taken into account, since the mass M equivalent to the reciprocative part is not merely a simple addition of the mass of the connecting rod 25 and the mass of the main shaft 26, but also the mass equivalent to the torsional movement of the main shaft 26 should be taken into account.

Now assume that fig. 3-5 illustrate: mB1, mB 2: mass of main weight, mS1, mS 2: mass of the secondary counterbalance, M: mass equivalent to the reciprocating portion, mrev: movable mass for stroke adjustment of the main shaft, θ: rotation angle (rad) ω: angular rotational speed (rad/S) — (d/dt) θ, S: spindle stroke width/2, L: offset amount of the center of mass of the spindle in the Y-axis direction, h 1: distance from the X axis to the main weight in the Y axis direction, hS1, hS 2: distance from the X-axis to the sub-weight in the Y-axis direction, RB1, RB 2: radius of rotation of the main counterweight (distance from center of mass), RS1, RS 2: radius of rotation (distance to center of mass) of the secondary balance weight, h: length of the link, G: center of mass of the connecting rod, a, b: distance from the end of the connecting rod to the center of mass.

Further, the mass M equivalent to the reciprocating portion may be given by the following mathematical expression (1).

[ EQUATION 1 ]

M＝mg+mgr+mgc＝mg+I·(2π/Lg)2+mc·b/h(1)

Wherein:

mg: the mass of the reciprocating part of the spindle (including the tool T and the like),

mgr: the mass equivalent to the torsional motion of the main shaft when the helical gear is molded,

mgc: the connecting rod is distributed to the mass part on the moving part,

i: the moment of inertia of rotation of the spindle about the Z axis,

lg: the main axis corresponds to the lead of the helix angle of the helical gear,

mc: the mass of the connecting rod.

Then, the balance of forces in the Z-axis direction, the balance of forces in the X-axis direction, the balance of torques about the Z-axis, and the balance of torques about the X-axis can be expressed by the following mathematical expressions (2) to (5).

(M+mrev)·ω2·S·cosθ+mB1·ω2·RB1·cosθ＝mB2·ω2·RB2·cosθ(2)

2mS1·ω2·RS1·sinθ+2mS2·ω2·RS2·sinθ+mB1·ω2·RB1·sinθ+mrev·ω2·S·sinθ＝mB2·ω2·RB2·sinθ(3)

mrev·ω2·S·L·sinθ+2mS2·ω2·RS2·hS2·sinθ-mB1·ω2·RB1·h1·sin

θ-2mS1·ω2·RS1·hs1·sinθ＝0(4)

mB1·ω2·RB1·h1·cosθ＝(M+mrev)·ω2·S·L·cosθ(5)

Further, the mathematical expressions (2) - (5) given above may be expressed by the following mathematical expressions (2) '- (5)' respectively.

[ equation 3 ]

(M+mrev)·S+mB1·RB1＝mB2·RB2(2)′

2mS1·RS1+2mS2·RS2+mB1·RB1+mrev·S＝mB2·RB2(3)′

mrev·S·L+2mS2·RS2·hS2-mB1·RB1·h1-2mS1·RS1·hS1＝0(4)′

mB1·RB1·h1-(M+mrev)·S·L＝0(5)′

As already indicated above, the masses mB1, mB2, mS1 and mS2 may be set so as to satisfy the mathematical expressions (2) '- (5)' given above.

Note that the positions of the sub-counterbalances 43 and 45 in the Y-axis direction may be located at the same positions as the positions of the centers of mass of the main shafts 26 in the Y-axis direction. In other words, hS2 is set to L. Thus, the mass ms1 of each

secondary weight

44 and 46 may be permanently made zero so that the

secondary weights

44 and 46 no longer need to be provided. Therefore, a simpler structure of the vibration damping mechanism can be obtained, and the balance weight can be selected more easily.

As has been described so far, according to the vibration damping mechanism of the gear processing machine of the present invention, when the counterbalances 41 to 46 are selected for processing the workpiece W into a helical gear, the forces in the X-axis direction and the Y-axis direction and the torques about the X-axis and the Z-axis are balanced, taking into account the torsional movement of the main spindle 26 corresponding to the helix angle to be formed on the workpiece W. Specifically, when the workpiece W is formed into a helical gear, the main spindle 26 reciprocates in accordance with a lead (angle) Lg corresponding to a helix angle to be formed on the workpiece W. The masses mB1, mB2, mS1 and mS2 are set (calculated) so that the counterweights 41-46 are selected, taking into account the mass (mgr) equivalent to the torsional movement of the main shaft 26. Therefore, the vibration generated in the machine tool can be reduced surely.

The present invention can be applied to a vibration damping mechanism of a gear processing machine capable of finely adjusting the position of a connected weight when the stroke width of a spindle is changed.

The above description is only one embodiment of the present invention, and is not intended to limit the present invention, and it is apparent to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A vibration damping mechanism of a gear processing machine, characterized in that a main shaft is reciprocated by a crank mechanism, the vibration damping mechanism comprising: a first balance shaft and a second balance shaft arranged in parallel to a crank shaft of the crank mechanism, the first balance shaft and the second balance shaft rotating in synchronization with the crank shaft at the same speed as that of the crank shaft, the first balance shaft rotating in a direction opposite to a rotating direction of the crank shaft, the second balance shaft rotating in the same direction as the rotating direction of the crank shaft;

a main balance weight detachably coupled to the crank shaft so as to reduce vibration in an axial direction of the main shaft; and a sub-balance weight detachably coupled to the first and second balance shafts so as to reduce vibration in a direction perpendicular to an axial direction of the main shaft, the main balance weight and the sub-balance weight being selected based on a stroke width of the main shaft and based on a helix angle to be molded in the gear blank.

2. The vibration damping mechanism of a gear processing machine according to claim 1, characterized in that: the primary weight includes: a front side balance weight having a phase offset by 180 ° from a phase of a main shaft supported eccentrically with respect to a center of the crank shaft; and a rear-side balance weight having a phase offset by 180 ° from that of the front-side balance weight so as to solve an imbalance caused by the offset between a position of a center of mass of the main shaft and a position of a center of mass of the front-side balance weight in an axial direction of the crank shaft.

3. The vibration damping mechanism of a gear processing machine according to claim 1, characterized in that: the auxiliary balance weight is arranged at the same position in the axial direction of the crank shaft as the position of the mass center of the main shaft in the axial direction of the crank shaft.