RU2359791C2 - Device for screw-cutting lathe for cutting of helical surfaces with varied pitches - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: device contains lead-screw installed with ability of axial movement, interlocked with displacement mechanism in the form of jaw with drive from worm gearing, case of which is installed with ability of displacement lengthwise lead screw axis, and hydraulic ram. It is outfitted by hydraulic pump assembly and connected with it following valve, interacting with jaw and hydraulically linked with hydraulic ram, providing power movement of worm gearing case, rigidly connected with lead screw.

EFFECT: increasing of durability and wear resistance.

2 dwg

Description

The invention relates to mechanical engineering, and more specifically to devices that expand the capabilities of screw-cutting lathes in terms of cutting screw streams with variable pitch on mill rolls for rolling products - bodies of revolution: balls, cylindrical and profile solid and hollow billets.

A device is known for a screw-cutting lathe for cutting screw surfaces with a variable pitch, see.with. USSR No. 268850, B23B 3/00, application. 15.01.1968, publ. 04/10/1970 The device contains a spindle mounted with the possibility of axial movement and kinematically connected with the movement mechanism in the form of a cam with a power short circuit drive. In this case, the kinematic connection of the lead screw with the cam is carried out by a movable splined connection and a fixed three-stage bevel-gear transmission, on the output shaft of which there is a cam.

The disadvantage of this device is the design complexity and low accuracy of cutting due to the presence of a long kinematic chain of transmission of rotation from the spindle to the cam.

The closest in technical essence is a device to a screw-cutting lathe for cutting screw surfaces with a variable pitch, containing a spindle mounted with the possibility of axial movement, kinematically connected with a movement mechanism in the form of a cam driven by a worm gear, the housing of which is mounted with the ability to move along the axis of the lead screw, and a hydraulic cylinder providing constant pressing of the cam to the support roller of the rack (see AS USSR No. 837643, B23G 3/10, decl. 03.09.1979, publ. 15.06.1981).

Replaceable cams during rotation are supported by the stand roller and provide axial movement of the gearbox with the spindle and the machine support according to the law determined by the cam profile. The lead screw moves the lathe support with considerable force.

A disadvantage of the known device design is to reduce the durability of the device due to wear of the worm gear and cam profile.

Increased loads on the worm gear and cam pair (cam and roller) that occur when moving the heavy support of the machine when cutting screw streams and when the support returns to its original position for the next pass, reduce the wear resistance of the worm gear and cam pair.

In addition, the hydraulic cylinder, which presses the cam against the rack roller, provides constant force interaction between the cam and the roller. This interaction also significantly reduces the durability of the cam pair, wearing out the working surface of the cam, as well as the outer and inner surface of the roller.

The objective of the present invention is to provide a device that allows to increase the durability and wear resistance by converting the worm gear and cam pair from power elements into kinematic elements operating at minimum load.

This object is achieved in that a device for a screw-cutting lathe for cutting screw surfaces with a variable pitch, containing a spindle mounted with the possibility of axial movement, kinematically connected with a movement mechanism in the form of a cam driven by a worm gear, the housing of which is mounted with the ability to move along the axis of the lead screw, and the hydraulic cylinder according to the invention is equipped with a hydraulic station and a follower valve connected to it, interacting with the cam and hydraulically with knitted with a hydraulic cylinder, providing power movement of the worm gear housing, rigidly connected to the lead screw.

Such a structural embodiment of the device allows to increase durability and wear resistance by moving the movable unit of the device (worm gear housing, spindle and machine support) with a hydraulic cylinder controlled by a follower valve, which is affected by the cam profile. Thus, the worm gear and the cam controlling the follower valve, from the power elements of the chain are transformed into purely kinematic, operating at minimum load and, therefore, wear out a little and remain accurate for a long time. In this case, the force of movement of the machine support, spindle, worm gear and cam during cutting (and returning to the initial position) is provided not by the worm gear and cam, but by the power hydraulic cylinder. A slight kinematic effort to move the tracking spool is created by a worm gear and a cam.

In addition, this constructive implementation allows to ensure the accuracy of the device due to the project deviations of the profile and pitch of the screw stream (profile barrel of the work roll), which is cut on the machine.

To explain the invention, a specific embodiment of the invention is provided below with reference to the accompanying drawings, in which:

figure 1 shows a General view of the device to a screw-cutting machine for cutting screw surfaces with variable pitch;

figure 2 is the same, a top view.

A device for a screw-cutting lathe for cutting screw surfaces with a variable pitch includes a lead screw 1 connected by a spline connection to the output shaft 2 of the machine feed box with the possibility of axial movement. The lead screw 1 is kinematically connected to the cam mechanism 3 driven by the worm gear 4. The cam 3 is placed on the shaft of the worm gear and the worm shaft is connected by a rigid coupling 5 to the screw 1. The worm gear housing 4 is mounted to move along the axis of the gear the screw 1 by means of a hydraulic cylinder 6. The device is equipped with a hydraulic station 7 and a servo valve 8 connected to it, interacting with a cam 3 and hydraulically connected to the hydraulic cylinder 6. The hydraulic cylinder 6 provides power movement of the core of the worm gear 4 and associated spindle 1 and machine support 9.

A device for a screw-cutting lathe for cutting screw surfaces with a variable pitch works as follows.

The housing of the worm gear 4 is moved using the hydraulic cylinder 6 in the guides parallel to the axis of the screw 1. Thus, the support 9 of the machine with a cutter cutting the screw profile of the roll 10 receives movement simultaneously from the rotation of the screw 1 and from its movement, additionally defined by the cam 3. To the machine-tool constant step, at first a constant value is added, which is set by cam 3, and then this value decreases, and the cut-in step gradually decreases, reaching the value of the "machine step" by the end of the cutting, we determine by setting up the machine.

The worm gear - lead screw system is moved by a hydraulic cylinder 6 controlled by a follow-up spool 8, which is influenced by the cam 3 profile. Since the cam 3 is located on the movable part of the device, opening the spool 8 during its rotation, it provides hydraulic pressure to the hydraulic cylinder cavity 6, which biases the housing of the worm gear 4 with the spindle 1 and cam 3 forward (towards the front headstock of the machine). Then the impact on the follower valve 8 from the side of the cam 3 stops, the additional movement stops and the cutting step is reduced to the machine. After that, the cam 3 profile provides an effect on the follower spool 8 in the opposite direction, and the hydraulic cylinder 6 responds to this by moving the system back (from the front headstock), the cutting step smoothly decreases and by the end of the cut section again reaches the value of a constant "machine step".

The proposed device to a screw-cutting lathe for cutting screw surfaces with a variable pitch in comparison with the known allows to increase the durability and wear resistance of the device.

Claims (1)

A device for a screw-cutting lathe for cutting screw surfaces with a variable pitch, comprising a spindle mounted with the possibility of axial movement, kinematically connected with a cam mechanism driven by a worm gear, the housing of which is mounted to move along the axis of the screw, and a hydraulic cylinder characterized in that it is equipped with a hydrostation and a follower valve connected to it, interacting with a cam and hydraulically connected to the hydraulic cylinder, providing yuschim force moving the worm gear housing fixedly connected with the lead screw.

Images