Method of assembling worm gear with coaxially mounted worm and gear ring

Abstract

FIELD: mechanical engineering.SUBSTANCE: method and device for its implementation are based on the precise self-determination of the positioning of the worm gear ring relative to the worm, combining their middle planes. The basis for the development of this method is the technological possibility of achieving gap-free contact during the assembly process of the worm gear with the worm, provided that there are no outer rings of tapered bearings on the wheel shaft. With such contact and due to the geometric parameters of the engagement of the links, their location is coaxial, and the middle planes are combined.EFFECT: assembly of a worm gearbox without the labour-intensive operation of adjusting bearings and gear engagement, by rearranging the gaskets in the wheel shaft supports from one side of the housing to the other, with repeated control of the accuracy of the contact patch location on the wheel teeth by paint.1 cl, 4 dwg

Description

[0001] The invention relates to mechanical engineering, with the possibility of increasing the quality and productivity of the assembly of a certain type of worm gearboxes.

[0002] Correct contact of the worm threads with the worm gear ring teeth, during their precision manufacturing, is possible only with the precise alignment of the midplanes of the worm and the gear ring of the wheel (GOST 3675-81 "Basic standards of interchangeability. Cylindrical worm gears. Tolerances"). According to the handbook of a mechanical engineer [1], the initial features of the design of the technological process of assembling a product are laid down in its assembly drawing. At the final stage, the assembly drawing of the worm gearbox receives additional elements in the form of gaps in the worm gear shaft supports filled with sets of shims. They are a sign of the adjustment operation, but are obtained as a result of calculating the dimensional chain in order to exclude additional processing of parts during their assembly in a unit, with a positive value of the master link. It is this that serves as the source of additional elements of the drawing.In accordance with the provisions noted in the reference book [1], the drawing of the worm gearbox contains 3 options for assembly technologies.

[0003] The first variant of the assembly technology is schematically as follows: the worm wheel shaft assembly is installed in the gearbox housing with the worm secured in the lower position; a cover is secured to the housing flanges, and then bearing caps are secured to the assembled housing; the actual dimensions of the gaps in the wheel shaft supports, between the cover flanges and the housing are measured; sets of linings of the appropriate thickness are selected, taking into account the axial clearance of a pair of tapered bearings; the bearing caps are released from fastening, and then secured to the housing together with the lining sets. Checking the engagement of gears assembled according to the first variant of the technology showed that the actual displacement of the midplane of the worm wheel toothed ring relative to the worm axis significantly exceeded the permissible value [2].

[0004] This circumstance indicates that the radial engagement of the worm gear with the worm sufficient for the calculated gear engagement does not ensure the geometric influence of the engagement on the axial position of the worm gear hub. The result of such a gear operation is shown in Fig. 1 as uneven wear along the length of the worm gear tooth.

[0005] Therefore, the second assembly technology option involves adjusting the axial position of the wheel by repositioning the shims from one side of the housing to the other. And checking the tooth contact rate in the transmission, "by paint" [3], proves to be repetitive and labor-intensive. This assembly technology option has been adopted in practice [2; 4-7].

[0006] In [8], a diagram of two dimensional chains was presented based on the condition of alignment of the midplanes of the gear worm ring and the worm (i.e., coaxiality). These chains determine the clearances between the ends of the bearing caps and the outer bearing rings. Their calculations eliminate the need to determine the nominal value of the total clearance used in the worm gear assembly. Adjusting two "communicating" clearances, with wide tolerances for the calculated values, proved to be very labor-intensive and was not adopted in practice.

[0007] The third variant of the worm gear assembly technology, associated with the coaxial arrangement of the transmission links, was not implemented.

[0008] The aim of the invention is to develop a method for assembling a worm gearbox based on the “self-determination” of the positioning of the worm wheel relative to the worm, ensuring an increase in the manufacturability and productivity of the assembly.

[0009] The development of this method was based on the technological feasibility of achieving gap-free contact during the worm gear assembly process, provided there are no outer races of tapered bearings on the gear shaft. With this contact, and due to the geometric parameters of the link engagement, their arrangement is coaxial, and their midplanes are aligned.

[0010] To assemble the worm gearbox using this method, two mechanics must work together. Additional technological equipment in the form of two devices was developed, manufactured and tested: 1 - a locking device for the vertical position of the worm wheel, equipped with a level, 1 pc. (Fig. 2); 2 - a locking device for the axial position of the worm wheel, relative to the gearbox housing, 2 pcs. (Fig. 3). The gearbox is assembled in the following sequence:

[0011] 1) the worm wheel shaft assembly, without the outer rings of the tapered bearings, is installed on the middle turns of the worm, fixed in the lower position of the gearbox housing;

[0012] 2) fitter 1 supports the worm wheel in a vertical position, and fitter 2 secures the retainer 1 on the gear ring of the wheel, with contacts on the end and cylindrical surfaces;

[0013] 3) mechanic 1 installs retainer 2 on the flange of the gearbox housing and secures it;

[0014] 4) fitter 2, when operating the lock 1 with both hands, ensures the vertical position of the worm wheel, and fitter 1, using the adjusting screws of the lock 2, forms a rigid connection between the gearbox housing and the worm wheel;

[0015] 5) fitter 2 installs retainer 2 on the other flange of the gearbox housing and secures it, then, using the adjusting screws of retainer 2, forms a second rigid connection between the housing and the worm wheel (Fig. 4).

[0016] Thus, the "technological method" makes it possible to achieve a coaxial arrangement of the worm gear links and to measure the dimensions between the end surfaces of the inner rings of tapered bearings and the gearbox housing with depth gauges. Each dimension is the sum of 2 dimensions: 1 - the difference in the standard parameters of a tapered bearing (T - B), where T is the mounting height of the bearing, B is the width of the inner ring, in accordance with GOST 333-71 "Single-row tapered roller bearings. Main dimensions", which determines the value by which the end surface of the outer ring protrudes relative to the end surface of the inner ring, to the working surface of the bearing cover; 2 - the nominal value of the dimension from the end face of the bearing outer ring to the end face of the housing, that is, the required size of the bearing cover Lк.

[0017] 6) The mechanics use depth gauges to measure the dimensions between the end surfaces of the inner bearing rings and the gearbox housing, L1 and L2; release the worm wheel from clamps 1 and 2; remove the worm wheel shaft assembly from the gearbox housing;

[0018] 7) apply a marking layer to the middle turns of the worm; install the outer rings of the bearings on the rolling elements, and the wheel shaft assembly into the gearbox housing, while the wheel shaft receives a working radial position, and the bearing covers have the dimensions of the cylindrical sections: Lк(1.2) = L(1.2) - (T-B)(1.2), taking into account the axial clearance of a pair of tapered bearings;

[0019] 8) install the housing cover on the housing and secure it, install the bearing caps and secure them.

[0020] This method of assembling a worm gear reducer is applicable to single-stage worm gear reducers with split housings, which are the most common [6]: 1 - with a worm under the wheel; 2 - with a worm above the wheel, in the presence of horizontal support surfaces on the housing cover. The method does not include labor-intensive factors used in practice: adjustment of bearings and gear engagement; use of adjusting shims.

[0021] The technological possibility of achieving gap-free contact during the assembly of a worm wheel with a worm, provided that there are no outer rings of tapered bearings on the wheel shaft, is also applicable to the assembly of a globoid gear.

[0022] Bibliographic list

[0023] 1. Handbook of a mechanical engineering technologist. Vol. 21 Edited by A.G. Kosilova and R.K. Meshcheryakov. - M.: Mashinostroenie, 1986. - 496 p.

[0024] 2. Dunaev P.F., Lelikov O.P. Design of machine units and parts: Textbook for students of technical specialties of higher education institutions. - M.: "Akademiya", 2004. - 496 p.

[0025] 3. Anurev V.I. Handbook of the mechanical engineer: T. 2 - M .: "Mashinostroenie", 2006. - 960 p.

[0026] 4. Kudryavtsev V.N. Worm gears. Metalworker's handbook. T. 2 - M.: Mashgiz, 1962. pp. 744-791.

[0027] 5. Ivanov M.N., Ivanov V.N. Machine parts. Course design: Textbook for mechanical engineering universities. Moscow, "Higher School", 1975. - 551 p.

[0028] 6. Reshetov D.N. Machine parts. Textbook for universities. - M., "Machine Science", 1989. - 496 p.

[0029] 7. James K. Simonellii. Introduction to Worm Gearing. URL: http.www.geartechnology.com / ext / resources / issues / 0393x / simonelli.pdf

[0030] 8. Dunaev P.F., Lelikov O.P., Varlamov L.P. Tolerances and fits. Justification of choice. - M.: Higher. school. 1984.

Claims

A method for assembling a worm gear reducer with a coaxially mounted worm and gear ring of the wheel, which consists in the fact that for the correct contact of precisely manufactured worm and gear ring of the wheel, a precise alignment of their middle planes is required, which is ensured by adjusting the axial position of the wheel by rearranging the gaskets in the wheel shaft supports from one side of the housing to the other, with repeated control of the accuracy of the location of the contact patch on the teeth of the wheel, according to paint, characterized in that the assembly is performed by two mechanics working together using technological equipment in the form of two devices: 1 - one lock of the vertical position of the worm wheel, equipped with a level; 2 - two locks of the axial position of the worm wheel, relative to the housing of the reducer;in the following sequence: the assembly unit of the worm wheel shaft, without the outer rings of the tapered bearings, is installed on the middle turns of the worm, fixed in the lower position of the gearbox housing; maintaining the worm wheel in a vertical position, fix the clamp 1 on the toothed ring of the wheel, with contacts on the end and cylindrical surfaces; fix the clamp 2 on the flange of the gearbox housing and, while checking the vertical position of the worm wheel, form a rigid connection between the worm wheel and the gearbox housing with the adjusting screws of the clamp 2; fix the clamp 2 on the other flange of the gearbox housing and form a second rigid connection between the gearbox housing and the worm wheel, with coaxially located transmission links;Using depth gauges, measure the dimensions between the end surfaces of the inner rings of the bearings and the gearbox housing L1 and L2, each of which is the sum of 2 dimensions: 1 - the difference in the standard parameters of a tapered bearing (T - B), where T is the mounting height of the bearing, B is the width of the inner ring; 2 - the nominal value of the cylindrical section of the bearing cover; release the worm wheel from the clamps and remove the worm wheel shaft assembly from the housing; apply a marking layer to the middle turns of the worm; install the outer rings of the bearings on the rolling elements, then install the wheel shaft assembly into the gearbox housing; install the housing cover on the housing and secure it; install the bearing covers and secure them.

Images