CZ2012163A3 - Ball-type screw - Google Patents

Abstract

The ball screw is formed by a threaded shaft (1) and a nut (2) with an internal thread (3) and at least one radial shaped hole (4) in which a transfer body (5) is arranged with a groove (6) for reversing the circumference. balls (7), housed in a threaded groove, formed by an external thread (8) of the threaded shaft (1) and an internal thread (3) of the nut (2). The guide body (5) is provided with locating pins (9) whose shape corresponds to a portion of the threaded groove. The locating pins (9) are provided with both bearing surfaces (14) for radially positioning the housing (5) in the female thread (3) of the nut (2) and on the extensions (10) above the running groove (6) for starting the bullet balls (7) into the groove (6). In the optimum position of the transfer body (5), its transfer groove (6) is continuously connected to the threaded groove and its side walls (11) extend into the gap (12) between the nut (2) and the threaded shaft (1) so that the surface of the threaded groove and the surface of the transfer groove (6) together with the adjacent surface of the hump (13) of the outer thread (8) of the threaded shaft (1) and the inner surface of the extension (10) form a continuous envelope of the circumferential ball path (7).

Description

Technical field

BACKGROUND OF THE INVENTION The invention relates to a ball screw consisting of a threaded shaft and an internally threaded nut and having at least one radial shaped bore, in which a transfer body with locating pins and a shaped transfer groove is provided for reversing the raceways. and internal nut thread.

BACKGROUND OF THE INVENTION

A ball screw is a precision motion screw that consists of a threaded shaft on which a nut unit is mounted by means of raceways. As the threaded shaft and nut move relative to each other, the raceways roll in a threaded groove formed by the threaded shaft external thread and the threaded internal thread, and it is therefore necessary to ensure their circulation in a closed circuit. There are two basic types of mechanisms that ensure closed ball circulation. The first type includes solutions that utilize ball transfer through several threads of the thread groove. These solutions use either tubular guide rails attached to the nut body or longitudinal guide channels drilled axially in the nut body to transfer the balls, and various guide bodies are incorporated in the nut or in the lids to allow the balls to be transferred from the threaded groove to the guide. or to the transfer channel. The disadvantages of these embodiments are the increased stopping dimensions, in the case of the tubular version the diameter of the nut is increased and in the version with the caps its length. The second type includes solutions that utilize the transfer of balls within one thread of a thread groove. These solutions use metal or plastic transfer bodies inserted into the radial bores formed in the nut and locked to the functional surfaces of the thread or the shoulder provided for them in the radial bores of the nut to transfer the balls, or the transfer bodies are arrested by a bushing or a ring . The nut of such a ball screw then has as many transfer bodies as there are ball bearing threads. These hitherto known embodiments are disadvantageous in that the ball rolls over the edge of the outer thread profile and that the balls are pushed into the wedge space when this edge passes, instead of being supported by a suitable structural element, such as in a ball turn over several turns . Both of these disadvantages cause a deterioration in the quality of the ball screw operation.

SUMMARY OF THE INVENTION

The aforementioned drawbacks are largely eliminated by a ball screw consisting of a threaded shaft and an internally threaded nut and having at least one radial shaped bore, in which a guide body with locating pins and a shaped guide groove for reversing the ball bearings in the threaded groove An external thread of a threaded shaft and an internal thread of a nut, according to the invention, characterized in that the locating pins have the shape of a corresponding part of the helical thread groove and are provided with bearing surfaces for radially positioning the gearbox in the internal thread of the nut and a groove for the running balls into the transfer groove, wherein the transfer groove of the transfer body is continuously connected to the threaded groove and the side walls of the transfer body The groove surface of the threaded groove and the transfer groove surface, together with the adjacent surface of the thread of the threaded shaft and the inner surface of the extension form a continuous envelope of the raceway of the raceways.

The position of the transfer body in the nut may be fixed by means of an adhesive and / or a sealant.

The transfer body is preferably formed of a metal abrasion-resistant anticorrosive non-magnetic material.

The transfer body may also be formed of a structural plastic material.

An advantage of the ball screw according to the invention is, in particular, that when the spline of the external thread of the threaded shaft, when transferred to the beginning of the working thread, does not copy the side shape of the threaded profile and thus do not have to overcome its edge, However, they are supported by the blade-like extension of the locating pins and transferred over the edge of the external thread profile of the threaded bolt by a partially closed transfer groove of the transfer body. A further advantage is the shape of the locating pins and their extensions, which allows the correct positioning of these extensions both to the internal thread of the nut and to the external thread of the threaded shaft. Such a modified transmission element eliminates

-3 the retention of the transfer balls as they pass over the back of the thread of the threaded shaft, thereby improving the flow of the ball screw.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of a ball screw according to the invention is shown schematically in the accompanying drawings. Fig. 1 shows a ball screw with a nut and gearboxes, in partial longitudinal section; Fig. 2 shows a portion of a threaded shaft with a gearbox nut mounted by positioning pins, in a partial longitudinal section; Fig. 3 shows a nut 4 and 5, respectively, are shown in axonometric views, wherein FIG. 4 is a side view of the transfer groove with locating pins provided with extensions, and FIG. 5 is a view from above. side of the locating pin with a bearing surface for aligning the transfer body in the nut.

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DETAILED DESCRIPTION OF THE INVENTION

The ball screw consists of a threaded shaft 1 and a nut 2 with an internal thread 3 and with through radial shaped holes 4 disposed helically around the circumference of the nut body 2. In the radial shaped holes 4 are arranged gear bodies 5 with shaped gear grooves 6 The shaped transfer groove 6 enables the recirculation of the raceways 7 across the spine 13 of the external thread 8 of the threaded shaft 1 in the extent of one pitch of the internal thread 3 of the nut 2. Nut 2 has as many transfer bodies 5 as there are bearing pitches of the internal thread 3 with race balls 7. The transfer bodies 5 are provided with locating pins 9 whose shape corresponds to a part of the helical thread groove. Supporting surfaces 14 are provided on the locating pins 9 in a part adjacent to the nut 2, which serve for radially positioning the transfer body 5 in the female thread 3 of the nut 2. The locating pins 9 are further provided with extensions 10 above the transfer groove 6. it lies with clearance in the external thread 8 of the threaded shaft 1 and serves for picking up the raceways 7 as they enter the transfer

The grooves 6 are provided with a clearance 15 provided on the outer surfaces of the locating pins 9 and their extensions 10.

Thus, the locating pins 9 serve both for the correct alignment of the guide bodies 5 in the internal thread 3 of the nut 2, i.e. for their correct alignment both in the lateral direction and the depth of the thread, and on the other thread 8 of the threaded shaft 1 from the threaded groove to the transfer groove 6 of the transfer body 5.

In the optimum position of the transfer body 5, its shaped transfer groove 6 is smoothly connected to the threaded groove formed by the external thread 8 of the threaded shaft 1 and the internal thread 3 of the nut 2, and its side walls 11 extend into the gap 12 between the nut 2 and the threaded shaft. and the surface of the shaped transfer groove 6 together with the adjacent surface of the spine 13 of the external thread 8 of the threaded shaft 1 and the inner surface of the extension 10 thus form a continuous envelope of the raceway 7. In order to fix the optimal position of the transfer body 5 in the nut 2 hole 4 above the transfer body 5 filled with adhesive and / or sealant. The transfer body 5 may be made of a metal abrasion-resistant anticorrosive non-magnetic material or a structural plastic material of suitable properties.

Industrial applicability

The ball screw is designed especially for the movement mechanisms of machine tools, robots, manipulators, etc., which require high efficiency of the conversion of rotary motion to linear and vice versa, high positioning accuracy and running quality with defined stiffness and load carrying capacity.

-6List of reference numbers used

..... threaded shaft

.....nut

..... nut internal thread

..... radial form hole

..... gearbox

..... transfer groove

..... orbital ball

..... threaded shaft outer thread

..... locating pin

..... extension of the locating pin

..... side wall of the gearbox

..... gap between nut and threaded shaft

..... threaded shaft outer thread

..... the contact surface of the locating pin

.....indentation

Claims (4)

PATENT CLAIMS A ball screw, comprising a threaded shaft and an internally threaded nut and having at least one radial shaped bore, in which a transfer element with locating pins and a shaped transfer groove is provided for reversing the raceways housed in a threaded groove formed by an external thread of a threaded shaft. an internal thread of the nut, characterized in that the locating pins (9) have the shape of a corresponding part of the helical thread groove and are provided with abutment surfaces (14) for radially positioning of the transfer body (5) in the internal thread (3) of the nut (2) by extensions (10) above the transfer groove (6) for running the raceways (7) into the transfer groove (6), wherein the transfer groove (6) of the transfer body (5) is smoothly connected to the threaded groove and side walls (11) of the transfer body (5) ) extend into the gap (12) between the nut (2) and the threaded shaft (1) such that the thread groove surface and the transfer groove surface (6) together with the adjacent surface of the spine (13) of the external thread (8) of the threaded shaft (1) and the inner surface of the extension (10) form a continuous envelope the orbits (7). Ball screw according to claim 1, characterized in that the position of the transfer body (5) in the nut (2) is fixed by means of an adhesive and / or a sealant. Ball screw according to claim 1, characterized in that the transfer body (5) is made of a metal abrasion-resistant anticorrosive non-magnetic material. A ball screw according to claim 1, characterized in that the transfer body (5) is made of a structural plastic material.