Method for estimating self-vibration of milling tool in the operating process

• US 7,810,417 B2
• Filed: 12/19/2006
• Issued: 10/12/2010
• Est. Priority Date: 12/20/2005
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kyoi, Masayuki, Onozuka, Hideaki
• Primary Examiner(s): Prone; Jason Daniel
• Assistant Examiner(s): SWINNEY, JENNIFER B
• Application Number:
  US11/640,870
• Publication Number:
  US 20070201956A1
• Time in Patent Office: 1,393 Days
• Field of Search: 82/11.1, 409/80, 409/186, 409/193, 700/173, 700/52
• US Class Current: 82/1.11
• CPC Class Codes: B23C 2220/48 Methods of milling not otherwise provided for
• CPC Class Codes: B23C 3/00 Milling particular work; Special milling operations; Machines therefor milling gear-teeth B23F, heat assisted machining B23P25/00
• CPC Class Codes: Y10T 407/19 Rotary cutting tool
• CPC Class Codes: Y10T 409/307224 with infeed control means energized in response to activator stimulated by condition sensor
• CPC Class Codes: Y10T 82/10 Process of turning

Abstract

In a cutting method of an oblique surface by a rotary tool, for analyzing in advance a stability limit depth of cut with respect to a self-excited cutting vibration in consideration of a pick feed amount and a work oblique angle and reducing the number of steps necessary for preparation and correction of NC data, a tool diameter, the number of cutting teeth and dynamic stiffness of the rotary tool, a cutting force coefficient determined by a combination of the tool and work materials, dynamic stiffness of the work, the pick feed amount, oblique angles between the tool and the work and the like are used as input values, an initial value of the stability limit depth of cut is determined based on the input values, and calculation is performed based on the initial value. In this case, the initial value is compared with the calculated value, the initial value is corrected by a certain rule, and the calculation is repeated until both the initial value and the calculated value fall in a constant error range to thereby calculate the stability limit depth of cut during the oblique cutting.

Claims

1. A method for calculating a stability limit axial depth of cut of self-excited cutting vibration is not generated during cutting of an oblique surface, the method comprising:

a first step of calculating a force acting on a cutting tool from an input initial value of an axial depth of cut by using, as input values, a cutting force coefficient determined by a combination of at least a tool geometry of said cutting tool and a work material, a tool diameter, a number of cutting teeth and a dynamic stiffness of said cutting tool, a depth of cut in a radial direction of said cutting tool, a dynamic stiffness of said work material, an angle formed by a rotation shaft and a feeding direction of said cutting tool, and a pick feed amount;

a second step of obtaining a calculated force acting on the cutting tool and a transfer function of a vibration system including said cutting tool and said work material to calculate a stability limit axial depth of cut;

a third step of adding to, a calculated stability limit axial depth of cut, an appropriate amount of correction based on a difference between said calculated stability limit axial depth of cut and an input axial depth of cut, and substituting for the initial value of said axial depth of cut; and

a fourth step of comparing said calculated stability limit axial depth of cut with the stability limit axial depth of cut substituted as said initial value of said axial depth of cut, and repeating from said first step to said third step, until a difference therebetween reaches a predetermined value or less.

2. The method according to claim 1, further comprising:

during the third step, repeating;

comparing said calculated stability limit axial depth of cut with said initial value of the axial depth of cut;

adding ½

of a difference between said calculated stability limit axial depth of cut and said initial value to said initial value of the axial depth of cut; and

again calculating said calculated stability limit axial depth of cut by using the added value as an initial value of said axial depth of cut.

3. The method according to claim 1, wherein said appropriate amount of correction is ½

of a difference between said calculated stability limit axial depth of cut and said input axial depth of cut.

4. A method for calculating a stability limit axial depth of cut during cutting an oblique surface without generating any self-excited cutting vibration, the method comprising:

determining forces which act on a cutting tool from each of input values, including a cutting force coefficient determined by a combination of at least a tool geometry of said cutting tool and a work material, a tool diameter, a number of cutting teeth and a dynamic stiffness of said cutting tool, a depth of cut in a radial direction of said cutting tool, a dynamic stiffness of said work material, a work oblique angle formed by a tool rotation shaft and a tool feeding direction of said cutting tool, and a tool movement amount in a direction substantially perpendicular to the tool rotation shaft and the tool feeding direction;

calculating a stability limit axial depth of cut based on the forces which act on the cutting tool and a transfer function of a vibration system including said cutting tool and said work material;

correcting the calculated stability limit axial depth of cut based on a difference between the calculated stability limit axial depth of cut and an input axial depth of cut, and substituting the corrected stability limit axial depth of cut for an initial value of said axial dept of cut; and

making a comparison between the calculated stability limit axial depth of cut and the stability limit axial depth of cut substituted as said initial value of said axial depth of cut, and repeating the calculation and correction, until a difference therebetween reaches a predetermined value.

5. The method according to claim 4, further comprising:

during the correction of the calculated stability limit axial depth of cut, repeating;

comparing the calculated stability limit axial depth of cut with said initial value of the axial depth of cut;

adding ½

of a difference between the calculated stability limit axial depth of cut and said initial value to said initial value of the axial depth of cut; and

again calculating the calculated stability limit axial depth of cut by using the added value as an initial value of said axial depth of cut.

6. The method according to claim 4, wherein an appropriate amount of correction made during the correction of the calculated stability limit axial depth of cut is ½

of a difference between the calculated stability limit axial depth of cut and said input axial depth of cut.