RU2278760C1 - Outer thread oscillation knurling method - Google Patents

Abstract

FIELD: plastic working of metals, namely formation of outer threads by knurling with use of rollers.

SUBSTANCE: method comprises steps of imparting rotation to knurling rollers and imparting radial feed motion at least to one roller. Each of said rollers includes boss with opening and key groove; central cylindrical, sizing and inlet portions. Cone inlet portions are formed on end part of rollers. Sizing and inlet portions of roller are arranged in periphery and they are shifted in axial direction by angle α to plane normal relative to rotation axis. Length l_s of sizing portion and axial shift angle α ( 0 -45°) are determined respectively according to formulae: l_s = L_th x k_bl/k_r; α = arctg [(L_th - l_s - l_in)D_rol where l_s - length of sizing portion of roller, mm; L_th - length of knurled thread, mm; k_bl -number of thread starts on blank; k_r - number of thread starts on roller; l_in - length of cone inlet portion of roller, mm; D_rol - outer diameter of oscillating rollers, mm.

EFFECT: enlarged manufacturing possibilities, improved efficiency, possibility for forming comparatively large length threads at lowered radial efforts.

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Description

The invention relates to mechanical engineering technology, to metal forming, in particular to the shaping of external threads by rolling.

A known method of rolling external threads thread rolling rollers with a radial feed, having a cylindrical shape [1]. The rollers receive a major rotational motion and a radial feed motion. The thread is rolled simultaneously over the entire length. The method allows to develop high performance and easily automate the process of rolling threads.

However, a significant drawback of the known method is the limited length of the thread being rolled, which cannot be greater than the width of the thread rolling rollers.

In addition, for rolling with a radial feed of long threads, large-pitch threads and trapezoidal threads, significant radial forces are required, which requires the use of expensive and uneconomical equipment.

A known method of rolling external threads with axial feed of the workpiece by thread rolling rollers having a tapered intake and cylindrical gauge parts [2]. The rollers receive the main rotational motion, and the workpiece receives the axial feed motion by self-tightening. Thread rolling along the entire length of the workpiece is carried out sequentially. Rollers allow you to roll threads of unlimited length. Radial forces during rolling with axial feed are minimal.

However, the known method has a relatively low productivity.

The objective of the invention is to expand the technological capabilities of rolling external threads by applying rolling with a radial-axial feed, which allows to obtain threads of a relatively large length with increased productivity and lower radial forces when rolling.

The problem is achieved by the application of the proposed method of oscillating rolling of external threads, in which the rolling rollers having an outer peripheral working surface and a hub with an aperture and tongue are given rotational movements and at least one roller radial feed movement, while the rolling rollers are taken with conical intake parts, located at the ends, and the central cylindrical gage part, located on the periphery and displaced axially at an angle α to the plane, perp dicular axis of rotation, and a hub with ends perpendicular to the axis, and the length of the calibrating part l _k and the angle of axial displacement α, taking values from 0 ° to 45 °, are determined respectively by the formulas:

l _k = L _p · k _zag / k _roll , α = arctan [(L _p -l _to -l _s ) D _roll ],

where l _k is the length of the calibrating part of the rollers, mm;

L _p is the length of the thread being rolled, mm;

k _zag is the number of thread starts on the workpiece;

k _roll is the number of thread starts on the roller;

l _s - the length of the conical intake part of the rollers, mm;

α is the angle of axial displacement, degrees;

D _roll - the outer diameter of the oscillating rollers, mm

Figure 1 shows the design of an oscillating roller that implements the proposed method; figure 2 is a view of B in figure 1; figure 3 - scheme of rolling threads of the proposed method; figure 4 is a view of figure 3; figure 5 - scan tracks of the rollers on the work surface provided D _roll = d _zag

The proposed method of oscillating rolling of external threads is carried out by a tool in the form of knurling rollers 1 having an outer peripheral working surface and a hub with a central hole and a tongue, which rotational movements and at least one roller give radial feed movement.

Oscillating rollers 1 for rolling an external thread comprise tapered intake 2 and a central cylindrical gauge 3 parts from the ends of the periphery displaced in the axial direction relative to the plane perpendicular to the axis of rotation by an angle α.

The hub 4 of the rollers 1 has ends 5, perpendicular to the axis of their rotation. In the hub 4 there is a central hole with a diameter d with a keyway for basing and installing the rollers on the machine. On the intake 2 and calibrating 3 parts of the rollers there is a multi-start thread with a lift angle equal to the lift angle of the thread rolled on the workpiece.

The diameters of the oscillating rollers, the number of thread runs on them and the permissible deviations of the profile elements are selected in the same way as cylindrical ones, the latter are regulated by GOST 9539-72.

The cone angle α _zk on the _intake conical parts is α _zk = 10 °. The length of the intake part l _s = 3P, where P is the pitch of the thread being rolled.

The angle of axial displacement α can vary from 0 ° to 45 ° depending on the outer diameter of the oscillating rollers D _{roll of the} length of the rolled thread L _p and the length of the calibrating l _k and conical intake l _{s of the} parts of the rollers and is calculated by the formula:

α = arctan [(L _p -l _k -l _h ) D _role ],

and the height of the cylindrical calibrating part of the oscillating rollers is selected based on the need to overlap the traces of the rollers on the workpiece in order to eliminate the risk of occurrence on the workpiece of sections with non-rolled thread (figure 5) in accordance with the condition:

l _k = L _p · k _zag / k _roll ,

where l _k is the length of the calibrating part of the rollers, mm;

L _p is the length of the thread being rolled, mm;

l _s - the length of the conical intake part of the rollers, mm;

k _zag is the number of thread starts on the workpiece;

k _roll is the number of thread starts on the roller;

α is the angle of axial displacement (takes values from 0 ° to 45 °), degrees;

D _roll - the outer diameter of the oscillating rollers, mm

In this case, the condition l _k ≥5 P.

Thread rolling according to the proposed method with oscillating rollers is carried out on existing thread rolling 2-roller machines. Oscillating rollers 1, having a rigid kinematic connection between each other, are set so that the protrusions of the threads on the rollers when rolling the thread fall into the grooves of the thread of the workpiece 6. The workpiece 6 is installed between the rollers 1 on a supporting knife 7.

According to an oscillating method, the main rotational movement V from the drive of a thread rolling machine (not shown) is communicated to the rollers 1. The workpiece 6 receives a rotation V _s from the rollers due to friction. One or both of the rollers is given a radial feed movement S _p . Under the action of the feed motion S _{p, the} rollers are introduced into the workpiece in the radial direction, forming a thread on the surface with a calibrating part.

At the same time, when the roller rotates, its intake and gauge parts, due to their axial displacement by an angle α, oscillate in the axial direction [3]. When the peripheral working part of the rollers oscillates, the thread on the workpiece is also formed by one of the intake parts of the thread rolling roller in the direction that the contact spot of the roller with the workpiece is currently moving.

Figure 5 shows a scan of the traces of the rollers on the machined surface under the condition D _roll = d _zag , where sections of the unrolled thread are visible. However, in practice, the diameter of the rollers D _{roll is} much larger than the diameter of the rolled workpiece d _zag and for the complete formation of the thread several tens of turns of the workpiece are necessary, therefore the thread will be completely applied to the workpiece.

The proposed oscillating method is used for metric threads with a diameter of 3 ... 68 mm in increments of 0.5 ... 6.0 mm. Roller thread: for right-handed threads - left multi-start, for left-hand threads - right multi-start. The number of calls ranges from 2 to 52; a larger number of approaches corresponds to smaller diameters of threads and smaller steps. The sizes of the rollers vary, mm: D _roll = 75 ... 207; B = 25 ... 125; d = 45 ... 100.

Oscillating thread rolling rollers are made of steel of the grades Х12М, Х6ВФ, Х12Ф1 for products with hardness НВ 160 ... 200; from steel 6X6V3MFS - for products with HB 370 ... 400.

Radial feeds for oscillating rollers are selected within the range of 0.02 ... 0.25 mm / rev; the number of turns that the workpiece makes during the profiling of the thread 4 ... 40; larger numbers correspond to harder workpiece materials.

The rolling speed depends on the material of the rolled workpiece: for brass 100 ... 120 m / min; mild steel 80 ... 100 m / min; steel of medium hardness 40 ... 60 m / min; solid steel 15 ... 20 m / min; titanium alloys 12 ... 14 m / min.

After the rollers are brought together by a distance sufficient to form a complete thread profile on the workpiece, the radial feed is stopped and the rollers make another complete revolution without radial feed to calibrate the workpiece and form a complete thread profile on its entire surface.

After that, the rollers are retracted in the radial direction and the workpiece is removed. Since the magnitude of the radial force when rolling threads with a radial feed is directly proportional to the length of the contact spot of the rollers with the workpiece in the axial direction and due to the fact that the width of the oscillating rollers is less than the length of the thread being rolled, the radial force when rolling the thread with the proposed oscillating method will be less than when rolling in the traditional way with cylindrical rollers with radial feed.

Example. When conducting production tests on a workpiece - a shaft made of steel GOST 1050-88 (rolled products as supplied), a M30 × 3.5-6 g thread 200 mm long was rolled on a 2-roller A2528 semi-automatic thread rolling machine with oscillating rollers having dimensions: D _roll = 140.651 mm; l _k = 40 mm; l _s = 10.5 mm; α _zk = 10 °; α = 45 °; k _roll = 5; permissible deviations of the profile elements in accordance with GOST 9539-72.

Oscillating rollers were informed of rotational motion with a speed of V = 20 m / min, radial feed S _p = 0.1 mm / rev of the workpiece, one revolution for complete profiling of the thread, and also one full revolution for calibrating the workpiece and forming a complete thread profile throughout its surface, while the workpiece made 15 turns.

The radial force during rolling by oscillating rollers was half less than when rolling by traditional cylindrical rollers.

Tests have established that the dimensions of the rolled thread are stable and correspond to the required accuracy level, the tool life corresponds to the resistance standards of thread rolling rollers according to GOST 9539-72, the surface roughness of the threaded surface meets the requirements of the drawing.

The proposed method allows rolling with high productivity and thread quality of a relatively large length with reduced radial forces.

Information sources

1. Yakukhin V.G., Stavrov V.A. The manufacture of threads. Directory. M: Mechanical Engineering, 1989. - P.38.

2. Yakukhin V.G., Stavrov V.A. The manufacture of threads. Directory. M: Engineering, 1989. - P.40 - prototype.

3. Popov ME, Avanish A. Finishing-hardening surface treatment with an oscillating tool. // STIN, 2003, No. 11. - P.34-36.

Claims (1)

A method of oscillating rolling of external threads, comprising communicating rotational motion to knurled rollers having an outer peripheral working surface and a hub with a hole and a keyway, and radial feed movements of at least one roller, characterized in that the knurled rollers are used with conical intake parts arranged with ends, and a central cylindrical gage part located on the periphery and offset in the axial direction at an angle α to a plane perpendicular to the axis of rotation, and a hub with ends perpendicular to the axis, and the length of the calibrating part l _k and the angle of axial displacement α, taking values from 0 to 45 °, are determined respectively by the formulas l _k = L _p · k _zag / k _roll ; α = arctan [(L _p -l _k -l _h ) D _role ], where l _k is the length of the calibrating part of the rollers, mm; L _p is the length of the thread being rolled, mm; k _zag is the number of thread starts on the workpiece; k _roll is the number of thread starts on the roller; l _s - the length of the conical intake part of the rollers, mm; α is the angle of axial displacement, degrees; D _roll - the outer diameter of the oscillating rollers, mm

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