RU2203161C2 - Apparatus for rotating spindle - Google Patents

Abstract

FIELD: machine engineering, machine tool manufacture, machine tools for milling parts such as crank shafts, wheel rims and shaft-pinions. SUBSTANCE: apparatus includes intermediate shaft mounted in body of spindle stock; braking ring fixed in circumferential direction, and main gearing whose driving gear wheel is mounted on intermediate shaft and whose driven gear wheel is mounted stationary on spindle. Apparatus is provided with compression spring and additional gearing whose driven gear wheel is mounted on spindle with possibility of rotation around its axis and whose driving gear wheel is mounted on intermediate shaft. Driving gear wheel of main and additional gearings are mounted stationary on intermediate shaft. Braking ring is mounted on spindle with possibility of abutting to end of driven gear wheel of additional gearing. Transfer ratio of additional gearing may be more than that of main gearing. EFFECT: improved design providing enhanced uniformity of spindle rotation due to preliminary loading of terminal link of kinematic circuit. 2 cl, 2 dwg

Description

 The invention relates to the field of mechanical engineering, in particular machine tools, and can be used in machines for round milling of parts, such as crankshafts and camshafts, wheel rims, gear shafts, etc.

 A device for rotating the spindle is known having the ability to transmit torques to the spindle, the values of which differ in a wide range. It contains a spindle and an intermediate shaft located parallel to each other in the headstock housing. On the spindle there is a pulley and gears, which can be engaged with gears located on the countershaft. In addition, on the spindle there is a clutch having the ability to engage with the belt pulley, which is mounted on the spindle with the possibility of rotation around its axis [I. Kucher Metal cutting machines. Fundamentals of design and calculation -L .: Engineering, 1970 p. 253].

 This device provides the transmission of torque from the spindle rotation drive directly through a belt drive or through the exhaust gears of the intermediate shaft. This allows processing both in turning mode and milling mode. However, this device when transmitting torque to the spindle through the intermediate shaft cannot ensure its uniform rotation, due to defects in the manufacture of gears that make up the kinematic chain of the device.

 The non-uniformity of the spindle rotation of this device will increase significantly when machining by milling with a circular feed of the part. This is due to the fact that when machining with a multi-blade tool, the part is subjected to the action of cutting forces, which are cyclical in nature. Under the influence of variable cutting forces, the spindle rotation mechanism experiences constant vibrations, as a result of which the magnitude of the elastic deformations of the kinematic chain of rotation of the spindle is constantly changing. This leads to a change in the gaps in the gears, causes uneven rotation of the part, which reduces the resistance of the cutting tool.

 To eliminate these phenomena in the spindle drives, providing a circular feed of the part, use devices for the preliminary loading of the kinematic chain of the rotation mechanism. The magnitude of the preload is usually set at 5-10% more friction and elastic deformation forces that occur in the mechanisms of rotation of the part when they are loaded by cutting forces [Yermakov Yu.M. Technology and tangential turning machines. -M.: Engineering, 1979, p. 112].

 A device for rotating the spindle is known, which comprises an intermediate shaft mounted in the housing of the headstock, a brake ring and a gear transmission. The drive wheel of this gear is mounted on the intermediate shaft with the possibility of movement along it and contact with the brake ring located on the support of the intermediate shaft. The driven wheel is fixed on the spindle.

 Such a device can rotate a part both during turning and during milling with a circular feed of the part.

 When the device is operating, rotation to the spindle is transmitted through a gear transmission, the drive wheel of which, moving along the axis of the intermediate shaft, is engaged with the driven wheel on the spindle. The end face of the drive wheel in this case is in contact with the end face of the brake ring. As a result of this, when transmitting torque to the spindle, the device for its rotation overcomes a certain moment of friction forces arising on the drive wheel in contact with the brake ring. Using such a preliminary loading of the kinematic chain of the device for rotating the spindle, not only the selection of the gaps in the gears is carried out, but also the displacements of various elements of the chain caused by its elastic deformations, which are caused by manufacturing errors of parts making up the kinematic chain of the part rotation mechanism, are eliminated. [A.S. 1704932, B 23 V 19/02. Spindle rotation drive, BI 2 from 01/15/92. ].

 The disadvantages of this device.

 Incomplete exclusion of uneven spindle rotation.

 This is due to the fact that the brake ring and the gear in contact with it are mounted on the penultimate link of the kinematic chain of the spindle rotation drive. Accordingly, the gaps and elastic deformations of the last link of this chain in this device are not compensated. This leads to uneven rotation of the part and uneven circular feed of the workpiece during milling.

 Intense brake ring wear.

 This is due to the fact that the ring is fixedly mounted relative to the drive wheel, therefore, the relative speed of the friction surfaces of the ring and gear is the largest of all possible in this mechanism.

The invention solves the following tasks:
- increasing the uniformity of rotation of the spindle due to the preliminary loading of the final link of the kinematic chain of the device for its rotation;
- a decrease in the wear rate of the brake ring due to a decrease in the speed of the relative motion of the friction surfaces.

 To achieve the technical result, the device for rotating the spindle comprises an intermediate shaft located in the headstock housing, a brake ring fixed in the circumferential direction, and a main gear transmission, the drive wheel of which is mounted on the intermediate shaft, and the driven one is stationary on the spindle.

 New in the invention is that the device is equipped with a compression spring and an additional gear transmission, the driven wheel of which is mounted on the spindle with the possibility of rotation around its axis, and the drive on the intermediate shaft. The drive wheels of the main and additional gears are fixed on the countershaft, the brake ring is mounted on the spindle with the possibility of closing with the end face of the driven wheel of the additional gear by means of a compression spring. An additional gear transmission is made with a gear ratio greater than the main one.

 Figure 1 presents the kinematic diagram of a device for rotating the spindle of a machine for circular milling; figure 2 - node a in figure 1 (assembly drawing, section).

 A device for rotating the spindle 1 is located in the housing of the headstock 2, which is installed on the frame 3 of the machine for circular milling. The intermediate shaft 4 is installed in the housing of the headstock 2 and is connected via a worm gear 5 with a stepless drive 6. The device is equipped with a main and additional gears. The driving wheels 7 and 8 of the main and additional gears are mounted on the intermediate shaft 4 motionless relative to the axis of its rotation. The driven gear wheel 9 of the main gear is fixedly mounted on the spindle 1, and the driven gear 10 of the additional gear is mounted on the spindle 1 with the possibility of rotation around its axis 11. The device contains a brake ring 12 mounted stationary in the circumferential direction on the spindle 1, the end of which is closed with the end gear wheel 10 compression spring 13, which is regulated by a nut 14, also mounted on the spindle 1.

 To reduce the wear rate of the brake ring 12, the gear ratio of the additional gear 8, 10 is greater than the main 7, 9.

 The device operates as follows.

 The rotation from the stepless drive 6 through the worm gear 5 is transmitted to the intermediate shaft 4 and from it through the main gear (wheels 7.9) to the spindle 1. The speed of the spindle 1 is determined by the gear ratio of this gear. The drive wheel 8 of the additional gear transmits rotation from the shaft 4 to the driven wheel 10, which rotates about the axis 11 of the spindle 1. Since the gear ratio of the additional transmission (wheels 8, 10) is larger than the main gear (wheels 7, 9), the wheel 10 rotates around axis 11 of the spindle 1 is slower than the brake ring 12 pressed against its end, rotating with the speed of the spindle 1. Between the ends of the ring 12 and the gear wheel 10 there is a moment of friction, which determines the amount of preloading of the entire kinematic chain. The magnitude of the moment of friction forces is determined by the force of pressing the ring 12 to the gear wheel 10.

 The difference in the rotational speeds of the ring 12 and the wheel 10 is not more than 5-10%, which leads to an insignificant speed of relative motion, and, accordingly, the abrasion rate of the friction surface of the brake ring 12. Since the preloading force is carried out directly on the spindle 1, this eliminates the gap opening in the kinematic chain of spindle rotation along its entire length. In addition, a slight difference in the speeds of rotation of the spindle 1 and the wheel 10, preventing its rotation, provides high durability of the brake ring.

Claims (2)

 1. A device for rotating the spindle, comprising an intermediate shaft mounted in the housing of the headstock, a brake ring fixed in the circumferential direction, and a main gear transmission, the drive wheel of which is mounted on the intermediate shaft, and the driven one is stationary on the spindle, characterized in that it equipped with a compression spring and an additional gear transmission, the driven wheel of which is mounted on the spindle with the possibility of rotation around its axis, and the drive on the intermediate shaft, while the drive wheels of the main and additional tion of gears mounted on the intermediate shaft fixedly, the brake ring is mounted on the spindle, with the closure with the end face of the driven gear wheels further through compression of the spring.  2. The device according to claim 1, characterized in that the additional gear transmission is made with a gear ratio greater than the main one.

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