SU729928A1 - Feeding drive control system of gear-cutting lathe - Google Patents

Description

one

The invention relates to the field of mechanical engineering and can be used in gear milling machines operating according to the running-in method.

A known open feed drive control system consisting of track switches, pressure gates interacting with them, a relay circuit, an executive device, controlling the feed per revolution of the workpiece by changing the feed rate ratio, stepless outside the cycle and continuous in the process, for example on ramming and exit}.

The scope of this control system is limited to machines with continuously variable-variable drives that are complex in structure.

The aim of the invention is to simplify the drive of the machine feeds by adjusting the effective feed per revolution of the workpiece by varying the long pulse feed rate.

This goal is achieved by the fact that the pressure stops interacting with the travel switches are mounted respectively on the product spindle and on the link kinematically associated with the tool sled.

in an amount equal to the number of pulses of the feed rate per revolution of the product and the number of ig4 pulses of the feed speed per workpiece processing cycle, with the stops mounted on the spindle being equally spaced; distances from each other, and the stops on a link kinematically associated with a sled at a distance corresponding to the current feed rates per revolution of the workpiece, calculated by the formula:

U) - X 5oz K

15

where SQ is the value of the feed per revolution of the workpiece acting at a given point on the track of the sled;

20

i the transmission coefficient between the sled and the kinematically connected link;

k is the number of impulses of speed 2 5 feed per revolution of the workpiece.

In a simplified version of the system, the pressure stops are mounted on the spindle of the product and on the slide on one. 30 right, parallel to their course.

Fig. 1 shows a scanning of a dividing cylinder of a gear wheel with a helical trajectory of the production engagement pole obtained on it, obtained by cutting with a constant ratio of the speeds of feed and rotation of the workpiece; Fig. 2 illustrates the inertia of the change in the i-pitch of the helical path caused by a stepped change in the angle of elevation: in Fig. 3 - scan of a broken helical path with constant pitch; in fig. .4 - the same with Soiriiyi in FIG. 5 is a scan of a broken helical trajectory, the pitch of which varies during processing; in fig. 6 is a block diagram of the proposed control system.

The proposed system implements a method for controlling the feed per revolution of the workpiece, in order to clarify which we consider the trajectory of the pole of the production gear in relative motion on the product.

The result of the addition of two movements: the translational (in the feed direction) and the rotation (around the axis of the workpiece) - this path for the case of processing a cylindrical gear has the appearance of a helix (figure 1). The pitch of this helix represents the actual value of the feed per revolution of the workpiece. It is this parameter, along with the cutting speed, that determines the cutting forces, the wear of the Mill and the removal of the metal, which is one of the adjustable parameters in connection with this. In the steady-state mode, the effective value of the feed per revolution coincides with the ratio of the feed rates and the rotation of the workpiece, while in the transition process the change in the effective value lags behind the change in the ratio of speeds, geometrically interpreted by the tangent of the elevation angle of the helical pole pole path. Switching, for example, the feed rate from one instantaneous constant value to another is graphically displayed by a step change in the elevation angle of the helical path, while the change in its pitch caused by this change occurs slowly and smoothly, and only after the workpiece rotation expires value (figure 2). The effect shown reflects 1} a feature of the milling process that is extremely important for feed control, namely, its inertia.

If the feed rate is periodically switched from the maximum to the minimum, and then vice versa from minimum to maximum, i.e. change it according to a rectangular periodic law, and after these changes are done several times for each revolution of the workpiece, we get a broken screw, trajectory of the engagement pole with a constant pitch (Fig. 3). In this case, the longer we work at the maximum and the smaller at the minimum, the more we get the pitch of this helical path. It follows that the effective value of the feed per revolution of the workpiece can be changed by changing the duration of the work at the maximum, periodically an integer number of times for each revolution of the workpiece, varying according to a rectangular law of the feed rate. The relationship of the duration of work at the maximum to the period, called the pulse filling factor, with the effective value of feed per revolution is reflected by dependence (1)

(one)

i-wax 5оэ 5уу1чи

T SovYiax-SowiiM

where is the effective value of the subcount per revolution of the workpiece, mm / rev :,

 . Mjrmvi t ovniw

SlAVnOIX

Bovna -,.

; S - minimum and maximum

AL win feed rate, mm / min;

- minimum and maximum of the rotational speed of the workpiece, rpm; B - the duration of the work

on 5owotx

T is the period of change in the ratio of feed rates and rotation of the workpiece.

An increase in the duration of work at the maximum entails a corresponding decrease in the duration of work at the minimum. Due to this, the result of the control will be the same if the pulse ratio of the pulse determined by the formula

ovnait so9

T 6o T1a5oUp-1i

(2)

- the duration of rg.bota

Where

PIC

 5 o hi-iiT

two constant values of the feed rate: the maximum and the minimum for the received range - any one can be obtained; effective value of the feed and turnover of the workpiece within this range. And if you combine the minimum with zero, then you can do

one constant value of the feed rate — the maximum (figure 4).

The pulse duration can also be varied during the cutting process, controlling the effective feed rate, for example, according to the program in the embedding and output areas in order to stabilize the load (Fig. 5).

The above reasoning applies to the control of radial and tangential feeds when gear milling, for example, worm gears.

The proposed system implements the described method, the period of change of the feed rate is specified by the angular path of the product spindle and is taken equal to or a multiple of its rotation, and the pulse duration is determined by linear movement of the slide between two switchings.

The machine control system Jfig.b) contains a travel contactless switch 1 mounted on the spindle housing, a flag 2 fixed on spindle 3, an electromagnetic clutch 4, a microswitch b stops 6 fixed on disk 7, a block of 8 intermediate relays. The rotation of the disk 7 is kinematically associated with movement of the body of the slide 9.

The system works as follows.

The traveling proximity switch 1 at the moment of passing. The flag 2 gives a command to turn on the electromagnetic clutch 4. Another microswitch 5, when pressed by the stops 6, gives the command to turn off the clutch 4.

The number of stops b is equal to the number of revolutions of the product per processing cycle, and the angular distances between them are proportional to the effective values of the reverse feed.

As an example of implementation, the system was built into a gear milling machine, the feed drive contains an asynchronous electric motor and a 15-speed box with an electromagnetic clutch that switches the chain of working feeds. The stops 6 on the disk 7 were arranged in accordance with the law of regulation of the current circulating feed, which ensures the stabilization of the torque at the incision sites to the output when machining a cylindrical sliding gear with a mo-. a barrel of 1 mm, a number of teeth 29 and a crown width of 18 mm.

The processing was done with a 63 mm high speed steel worm milling cutter in the following modes: cutting speed of 32 m / min, feed rate for which the feed box was adjusted, 47 mm / min; the effective feed rate per revolution of the workpiece in the initial incision phase was la 7.5 mm / rev., on steady cutting 1.5 mm / rev., which corresponds to a feed rate of 8.2 mm / min.

The application of the proposed control system allows the infinitely variable regulation of the current feed rate. The turn of the workpiece, both outside the operating cycle and in the machining process on gear milling machines with step-adjustable drives. Moreover, the number of stages in the feed drive can be reduced to two or even one, which will simplify the structure of feed drives of gear milling machines.

15

Claims (2)

1. The feed drive control system of a rolling milling machine, containing directional switches, interacting elements, such as pressure stops, a relay circuit and actuators, which, in order to simplify the drive of the machine’s feeds by adjusting . The effective feed per revolution of the workpiece by varying the pulse rate of the feed rate, the pressure stops are installed respectively on the product spindle and on the link, kinematically connected with the tool sled, honors equal to the number of pulses of the article feed rate per revolution and including: im5 pulses feedrate for the workpiece processing cycle, and fixed stops on the spindle located at. equal distances from each other, and the stops on the link, kinematically connected with the slide, are at a distance corresponding to the current feed rate per revolution of the workpiece, calculated by the formula: . boE 5 if.l where 5g. L acting at this point one way. skid value per turn of the workpiece; 0 transfer ratio between 1 sled and kinematically related link; k - the number of speed pulses filing for the turnover of the workpiece, five 2. Pop. 1 system, differing from the fact that the pressure stops are mounted on the product spindle and on the slide on a single straight pipe parallel to their movement. Information sources, taken into account in the examination 1. Kosak I. New grinding wheel hob. Czechoslovakia, heavy industry, 1974, 3. m io Urn jnij Fug. L max