UA130772U - METHOD OF MILLING OF TORQUE BODIES - Google Patents

Abstract

A method of milling rotary bodies with a final cutter, in which the milling cutter provides a constant speed of rotation, and the workpiece - a linear and circular flow, the values of which are continuously changed. Regardless of the size of the cut-off cutter, the cutting depth is taken to be the same as the cut-off value. The change in the magnitude of the linear flow is carried out by adjusting the speed of the rotor of the motor of the actuator of the feed depending on the technological load acting on the feed mechanism during cutting, and the circular feed of the workpiece is coordinated with a linear flow using a kinematic chain of gearwheel feed drive with workpiece spindle.

Description

The useful model belongs to the engineering technology, in particular, it concerns the processing of metals by cutting, and can be used for processing parts on milling machines.

A widely known method of milling parts of the shape of the bodies of rotation with cylindrical cutters, in which the cutting tool is given continuous rotation, and the parts - feed movement (1).

This method does not provide stabilization of the load on the tool during fluctuations of the allowance, which does not allow to increase productivity to the maximum permissible level. This limits the scope of possible use of this method.

The milling method |2) is also known, which is taken as the closest analogue. In this way, the tool is given a constant rotation frequency, and the feed is continuously changed according to a certain dependence.

The known method has a special purpose, because it is used when rotating the milling cutter and the workpiece around mutually perpendicular axes. It does not provide stabilization of the tool load when the machining allowance is changed.

The task of a useful model is to eliminate the mentioned shortcomings, increase the productivity and reliability of processing by stabilizing the load on the tool, regardless of the size of the allowance being cut.

The task is solved by the fact that the method of milling the bodies of rotation with an end mill, in which the cutter is given a constant frequency of rotation, and the workpiece is given linear and circular feeds, the values of which are continuously changed, according to a useful model, the cutting depth is taken equal to the value of the allowance, and the value of the feed is determined from the ratio given in the formula depending on the technological load acting on the feed mechanism during cutting and the cutting depth, and the value of the linear feed is changed by adjusting the frequency of rotation of the electric feed motor, and the circular feed of the workpiece is coordinated with the linear feed using a kinematic chain, which connects the lead screw of the feed drive with the spindle of the workpiece.

The scheme of implementation of this method on the example of milling with an end mill of a curved profile of a disc cam is shown in fig. 1. The following designations are used in this diagram: 1 - end mill; 2 - disk cam workpiece; Z - dividing head; 4 - milling machine table; 5 - running screw of the feed drive; b - electric motor of the feed drive; 7 - load sensor; 8 - signal amplifier; 9, 10 and 11 - respectively, comparative, program and executive devices.

It is known that during milling, the cutting force is usually divided into the following components: circular P acting normal to the cutter tooth surface, axial P; and radial U. The U component creates a load on the kinematic supply chain. It is also known that the cutting force and its components depend on the working feed rate. Therefore, by changing the speed of the working feed, it is possible to control the cutting force and its components.

The proposed method is based on the fact that by limiting the load of the kinematic feed chain, thereby limiting the components of the cutting forces.

As can be seen from fig. 2, the component of the cutting force acting on the feed mechanism,

Ru - P, soz5o o () where 9 is the angle of inclination of the cutter teeth relative to its axis.

From the theory of metal cutting |Z, p. 218) it is known that the circular component of the cutting force ro - СрибБЯВОех 2 ptarmro 0 SR rardur | (2)

R, Sv nie. and where is the wheel force, N; - a constant coefficient depending on the type of processing, the processed material and the milling cutter; Y. cutting depth, tt; 5 - speed of working feed, mm/min;

B - width of milling, (pt; y - diameter of the cutter teeth; 0 - diameter of the cutter, mm; n - frequency of rotation of the cutter, rpm; Р, Р.Р, Яр. Р. indicators of degrees; " - general corrective coefficient.

Substituting (2) into (1), we get

Wednesday

Ru - ---2-- --хк о -со5о dr

Ota I (3)

It is known from the theory of adaptive control that in order to increase the accuracy of processing, it is necessary to stabilize the technological load. For this purpose, automatic regulation systems are used, which include sensors, comparative and control devices. It can be seen from equation (3) that the problem of load stabilization in the feed drive of the milling machine can be solved. The working feed rate can be determined from this equation as follows:

Rap" 5-U- I - - - --

Sri"V'?2Ko sovo (4). Ur -1 .

In the case of processing with end mills, formula (4) also takes the form

And rur'ptv

Wed"V"2Kr so5o ; (5)

When processing with an end mill a workpiece with a constant width V and a constant component P, it can be noted that

Op

And ry on

СрВ "2Kusozo , (6) and then, substituting (b) in (5), we obtain the speed of the working feed

R

5--D- A

Go (7)

It can be seen from dependence (7) that when the feed is changed according to this ratio, stabilization of the cutting force and its components is ensured. It is proposed to obtain such an effect as follows.

The end mill 1 (Fig. 1) is fixed in the spindle of the milling machine and rotates at a constant frequency. The workpiece of the cam 2 is installed in the spindle of the dividing head 3 fixed on the table 4 of the machine. The workpiece is provided with both linear and circular feed.

The linear feed 5 of the table 4 of the machine together with the dividing head Z and the cam 2 is provided by the adjustable electric motor 6 through the clutch and the lead screw 5. The circular feed "kK from the lead screw 5 of the machine table through the guitar of variable gears 2/6. s/a gears 7 Their 23/74 and worm pair K/jak is received by the spindle of the dividing head 3 with the machined cam 2.

Z The amount of feed is determined by formula (7) and changes as the cutting depth changes. In fig. It is shown that the allowance and the same cutting depth during processing of the cam profile change from zero to the maximum value of Kk. This change occurs at the angle of rotation of the cam 9. The change in the cutting depth, as can be seen from dependence (7), causes a continuous change in the amount of feed, creating a constant load in the drive. When the cutting depth increases, the feed rate decreases, and when the depth decreases, the feed rate increases. This ensures processing with the maximum allowable feed for the load of the drive and increases the reliability and durability of the drive.

The change in the amount of feed is carried out by adjusting the frequency of rotation of the electric motor 6 (Fig. 1) depending on the technological load acting on the feed mechanism during cutting. This load is monitored by sensor 7, converted into an electrical signal, which is amplified by device 8.

The amplified signal is fed to the comparator 9, where it is compared with the normalized signal coming from the software device 10. The mismatch signal is fed to the executive device (frequency inverter) 11, which accordingly changes the frequency of the supply voltage of the electric motor b, as a result of which the frequency of its rotation changes , and therefore the feed rate.

The dividing head C is used to rotate the workpiece of the cam 2 around its axis by a certain angle 0 and coordinate with this rotation the feeding of the table with the workpiece in the radial direction to the mill to obtain a curvilinear profile of the cam. This coordination is carried out with the help of a kinematic chain of gears of the dividing head from the running screw 5 of the machine. Tuning of this chain is carried out by selecting variable ABS gears, dividing head guitar.

The essential differences of the proposed method of milling are that the combination of interrelated actions outlined in the formula provides a positive effect, which is reduced to maximum productivity when stabilizing the load and elastic deformation in the technological system of the machine, which contributes to increasing the accuracy of processing.

The method can find application in processing by cutting shaped profiles of parts such as bodies of rotation on milling machines.

Sources of information: 1. Ass. USSR Mo 874274. V 23 S 3/04. Method of milling bodies of rotation. - Bull. Mo 39, 1981 - P. 66. 2. A.b. USSR Mo 902987. V 23 S 3/04. The method of processing bodies of rotation. - Bull. May 5, 1982 - S. 58.

Z. Handbook of metal cutting / F.N. Abramov, V.V. Kovalenko, V.E.

Lyubimov et al. - K.: Technika, 1983. - 239 p.

Claims (1)

USEFUL MODEL FORMULA A method of milling bodies of rotation with an end mill, in which the mills provide a constant frequency of rotation, and the workpiece - linear and circular feeds, the values of which Zo are continuously changed, which differs in that regardless of the size of the allowance cut by the mill, the cutting depth is assumed to be the same with the value of the allowance, and the value of the linear feed is determined from the ratio t 5. Mrs. Rou. . . and where is the linear feed rate; - the component of the cutting force acting on the feed mechanism; " - depth of cut; xr. degree indicator; A - coefficient that takes into account the conditions of cutting, and the change in the amount of linear feed is carried out by adjusting the frequency of rotation of the rotor of the electric motor of the feed drive depending on the technological load acting on the feed mechanism during cutting, and circular feed workpieces are aligned with the linear feed by means of a kinematic chain of gears connecting the lead screw of the feed drive with the workpiece spindle.