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

• US 20070201956A1
• Filed: 12/19/2006
• Published: 08/30/2007
• Est. Priority Date: 12/20/2005
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kyoi, Masayuki, Onozuka, Hideaki
• Granted Patent: US 7,810,417 B2
• Time in Patent Office: Days
• US Class Current: 407/30
• 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 in which any self-excited vibration is not generated, the method using, as input values, a cutting force coefficient determined by a combination of at least a tool geometry of a cutting tool and a work material;

a tool diameter, a number of cutting teeth and dynamic stiffness of said cutting tool;

a depth of cut in a radial direction of said cutting tool; and

compliance transfer functions of said cutting tool and said work, the method comprising the steps of;

obtaining a cutting start angle and a cutting end angle of the cutting tooth from an input initial value of the axial depth of cut with respect to a model of cutting of an oblique surface in which an angle formed by a rotation shaft and a feeding direction of said cutting tool and a pick feed amount are further designated;

obtaining a transfer function of a vibration system including said cutting tool and said work to calculate a stability limit axial depth of cut from a characteristic equation of said function; and

comparing said calculated stability limit axial depth of cut with said initial value of said axial depth of cut to correct said initial value of said axial depth of cut as much as an appropriate amount, and repeating from said step of obtaining the cutting start angle and the cutting end angle of said cutting tooth to said step of calculating said stability limit axial depth of cut, until a difference between said calculated stability limit axial depth of cut and said initial value reaches a predetermined value or less.

2. The method for calculating the stability limit axial depth of cut according to claim 1, further comprising:

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 the calculated stability limit axial depth of cut and the 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.