SU638020A1 - Method of control of gear-hobbing modes - Google Patents

Description

The invention relates to the field of machine tools. The known method of controlling cutting modes during gear milling according to the run-in method is characterized in that the ratio of the feed rates and the B1J ID of the workpiece l change the actual value of the feed per revolution of the workpiece. On machines with step-adjustable drives, for example, with multi-link feed boxes and speeds, the feed per revolution of the workpiece can take only discrete values within a narrow range, which makes it necessary in many cases to work in modes other than optimal. Changing the mode during machining on such machines does not apply. On machines with infinitely adjustable gears, you can assign any value of the revolving feed within the wide range, as well as change it continuously during machining, for example, to stabilize the load on the embedding and output sections. However, the use of stepless-re-. the drive to be guided increases the cost of the machine and the cost of milling on it. Thus, the known method of control of the gear milling modes, applied to machines with step-controlled drives, limits technological capabilities, and with respect to machines with steplessly-controlled drives, efficiency. The aim of the invention is the implementation of the stepless adjustment of the feed per revolution of the workpiece on machines with a step-adjustable drive of feeds and reducing the number of steps in it to one to two. This goal is achieved. We mean that the control of the effective value

the feed per revolution of the workpiece is carried out by changing the duration of the work at the maximum, for example, the feed rate, which varies periodically according to the law of a rectangular impulse. In this case, the frequency-change in the feed rate is taken equal to or a multiple of the rotational speed of the workpiece, and the pulse filling factor is adjusted to the selected actual feed value per workpiece rotation and is determined by the formula ilMSi where Sg, is the effective value feed per revolution of the workpiece, mm / rev. wv «a W miH and о mm and b v« ax% minj minimum and maximum feed per revolution of the workpiece mm / min; SwiVi jwoSK minimum and maximum of the speed of rotation of the workpiece, rpm hiOiK duration of work for T — period of change in the ratio of the speeds of feed and rotation of the workpiece. An increase in the duration of work at the maximum entails a corresponding decrease in the efficiency of work at the minimum, as a result of which the result of the control will be the same if, according to the selected effective feed rate per revolution of the workpiece, the pulse ratio determined by the formula

X. eC

 „OPSZA,

C2)

 ovyiaK, owiH

where, the duration of work on

SOWIM

FIG. 1 shows a scan

a gearwheel cylinder with a helical trajectory applied thereto on the basis of the lution of the gearing obtained when cutting with a constant ratio of the speeds of feed and rotation of the workpiece; fig 2 -. the inertia of changing the step of the viit trajectory, caused by the step Tbfri by changing the angle of the bottom; in fig. 3 - scan of a broken helical path with constant pitch; in fig. 4 - the same as, Oi n

6380204

FIG. 5 is a scan of a broken helical path, the pitch of which varies during processing.

Consider the trajectory of the procurement pole, it moves to a new steady-state value (see Fig. 2). The effect shown reflects the property of the tooth milling process, which is crucial for the feed control, namely, its inertia,, and the use of this effect. The proposed method is established.

Claims (1)

Indeed, if the feed rate is periodically switched first. from maximum to minimum, and then vice versa, i.e. change it according to a rectangular law, and if these changes are made an integer number of times for each hook in relative movement on the product. Being the result of the addition of two movements: translational feed direction, and rotational movement around the axis of the workpiece, this trajectory for the case of machining a cylindrical gear has the appearance of a helix (see Fig. 1). The pitch of this helix is the difference in the coordinates of the position of the cutter in a given cavity between the teeth at the current and previous revolutions of the Z-cook or the effective feed rate per revolution of the workpiece. It is 5 THIS parameter, along with the cutting speed, that determines the force, the wear of the mill and the removal of metal, in connection with this one of the adjustable parameters. In the steady state, the actual feed per revolution value coincides with the ratio of the feed and rotation speeds of the workpiece, while in the transition process the change of the effective value lags behind the change in the speed ratio geometrically interpreted by the tangent of the elevation angle of the helical pole of the engagement. Switching, for example, the feed rate from one instantaneous constant value to another is graphically displayed by a stepwise change in the elevation angle of the screw path, while the change in its pitch caused by this change occurs slowly and smoothly and only after the turnover of the workpiece turns out, we get a broken screw path engagement poles with constant pitch (see fig. 3). In this case, the longer we work at the maximum and less at the minimum, the more we get the pitch of this helical trajectory. Hence 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 turn of the workpiece, varying according to the rectangular law of the feed rate. The ratio of the duration of work at the maximum to the period, called the coefficient pulse filling, with the effective feed value at turn speed is reflected by the dependence 7. The result will be the same if the pulse duty cycle changes, i.e. the ratio of the duration of work at the minimum to the period, determined by formula (2). Thus, there are only two constant feed rates: maximum and minimum for the accepted range, you can get any effective 3Ha4eHiie feed per revolution of the workpiece within this range, And if you combine at least zero, then you can do with one constant speed value the feed rate is maximum (see Fig. 4). A similar result is obtained when the pulse duration is changed periodically by the switching speed of the rotation of the dividing circuit, or, more generally, the ratio of the feed and rotational speeds Preparations. The proposed method includes the possibility of changing the pulse duration during the cutting process, controlling the current feed, for example, according to the program in the embedding and exit areas, in order to stabilize the load (see Fig. 5). The above reasoning and, therefore, the method itself is extended to the agb management of radial and tangential feeds. As an example of the implementation of the proposed method, a cylindrical sliding wheel with a 1 mm module, a number of teeth 29, a 18 mm wide crown was processed. bop milling machine mod. 5K301P, the water supply of which contained an asynchronous electric motor and a 15-speed gearbox. The processing was performed in a semi-automatic mode in the following sequence after the accelerated approach from the command given at a given point of the spindle's angular path, the axial feed was activated, which was set to the maximum value for the operating range; Having completed the calculated for the first revolution of the workpiece, the feed drive is turned off by a command given at a point on the linear path of the table corresponding to this duration; upon completion of the workpiece rotation at the same point of the spindle product's angular path, the feed is switched on again, the second period of its change begins, and t, e, and the duration of switching on the feed drive changed from turn to turn in accordance with the program that provides load stabilization embedding and exiting. The machining was done with a YEH 63 mm milling cutter made of high-speed steel in the following modes: cutting speed 32 m / min, feed rate for which the feed box was adjusted, 47 mm / min, the effective feed per revolution of the workpiece in the initial incision phase was 7.5 mm- / rev, at steady cutting 1.5 mm / rev, which corresponds to a feed rate of 8.2 mm / min. The application of the proposed method of controlling cutting modes during gear milling will allow for the infinitely variable regulation of the current value of the feed per revolution of the workpiece, both outside the operating cycle and during processing on machines with step-adjustable drives. Moreover, due to the fact that in order to ensure the proposed method, it is sufficient to have two or even one post-pumping speed of the feed, its implementation will simplify the structure of the flow rates of gear milling machines. Thus, the proposed method extends the possibility of optimizing the gear milling process to machines with stepwise control and drive. The implementation of the method by the use of simple and easily accessible means will give an increase in the productivity of gear milling by 30-50% only due to the stabilization of the load on the Brezash1 output and output. -. . Claims. The method of controlling the run-in gears by the running-in method, consisting in a purposeful change in the ratio of the feed amount and the rotational speed of the workpiece, which is so that, in order to carry out stepless adjustment of the current feed rate per turn of the workpiece on machine tools with step-adjustable drives, the duration of work at the maximum value of the ratio of the feed amount and the speed of rotation of the workpiece are periodically, an integer number of times for each revolution of the workpiece, it is a rectangular pulse, and the pulse duration is chosen in accordance with the required effective value of the feed per revolution of the workpiece and the filling factor and pulse duty cycle are determined according to the formulas . OSH1M C1) C. -c ortiajT ovitiii 1I - rshduG o (.one G 5 -S) 1 ovniM Q is the effective value of the suction per turn of the workpiece, mm / rev; Um w-in ovniv.- U1 ,, oshah N ,,, rti; minimum and maximum feed rates. mm / min; ,; "Minimum and maximum value of the rotational speed of the workpiece, rpm; t and t fy, ci are the duration of work, respectively, on and, с (x; T is the period of change in the ratio of the feed and rotation speeds of the workpiece. about 2, a method according to claim 1, characterized in that the duration of the work at the maximum feed rate is changed, an integer number of times for each revolution of the workpiece, according to the law of a rectangular impulse at a constant speed of rotation of the workpiece. -3. A method according to claim 1, characterized in that they vary the duration of the work at the maximum speed of the rotation of the workpiece, an integer number of times for each revolution of the workpiece, according to the law square pulse, at a constant feed rate. 4. The pop method, characterized in that, in order to reduce the control the number of commands, the period of change in the ratio of feed rates and rotation; neither the blanks are taken equal to the period of the turnover of the blanks. 5. Method according to paragraphs. 1 and 2, that is, in order to making it possible to simplify the feed drive, the minimum value of the feed rate is taken to be zero. Sources of information taken into account in the examination 1. Patent of Great Britain No. 1002592, cl. In 2 K, 1973. inax four