MXPA98003058A

MXPA98003058A - Manufacture of bearings for movement lin

Info

Publication number: MXPA98003058A
Application number: MXPA/A/1998/003058A
Authority: MX
Inventors: Lyon Gregory
Original assignee: Thomson Industries Inc
Priority date: 1995-10-20
Filing date: 1998-04-17
Publication date: 1998-11-12

Abstract

The present invention relates to a method for forming a rail for use in a bearing assembly for linear movement, characterized in that it comprises the steps of: forming an elongated base member having an insert mounting portion, the insert mounting portion having respective surfaces with at least one longitudinal groove thereon; elastically deforming a load bearing insert without causing substantial plastic deformation to the load bearing insert; inserting a load bearing insert elastically deformed on at least one longitudinal groove; and allowing the elastically deformed load bearing insert to reacquire its shape in contact with the insert mounting portion.

Description

MANUFACTURE OF BEARINGS FOR OVTMIEM Q LINEAL ** HCT? FM'rp- < OF THE INVENTION 1, C TT ?? 1st Trnraam An The present invention relates to a low cost manufacturing technique for producing linear motion composite bearing structures. More particularly, this manufacturing method greatly simplifies the manufacture of a bearing rail and at the same time facilitates efficient and cheap production. 2. Decription of the Technique. Related Linear motion bearing assemblies are well known in the art and are used to move a machine and machine tools and other equipment relative to one another. These bearing assemblies typically include rail and support structures, rolling elements and provisions for recirculation and lubrication. See, for example, U.S. Patent No. 4,932,067 to Pester et al. Typically, these bearings are made of monolithic structures made of high quality bearing steels. The manufacturing sequence of the rail and the REF: 27316 support for this type of bearing assemblies is typically by cold setting, machining, heat performance and polishing. The process is usually carried out in elaborate and expensive machining equipment, which leads to a substantial cost. In addition, a feature of high quality bearing steel is its rigidity. This characteristic results in a requirement of extreme precision in the polishing of the tracks that support the load and a highly accurate installation of the linear motion bearing assembly to avoid overlapping voltages in contact portions. Attempts have been made in the past to reduce the amount of bearing steel required for processing by applying high quality bearing steel only in the contact areas. See, for example, U.S. Patent Nos. 3,900,233 and 4, 025, 955 to Thompson; and U.S. Patent Nos. 4,515,413, 4, 527, 841, 4,531,788 and 4,576,421 for Teramachi. Various techniques are provided for attaching the bearing steel insert to the support body. Techniques include pressure adjustment, dovetail coupling, cold forming of the bearing steel insert and cold forming of the support structure. Attempts have also been made in the past to improve the positioning of the bearing steel in the support body. For example, U.S. Patent No. 4,576,420 to Lehman, describes the use of preloading the rolling elements to place the bearing steel in a support. U.S. Patent No. 4,774,247 to Isert describes the use of an integral clamping force provided by the support structure for retaining the bearing steel. U.S. Patent No. 5,067,823 to Kasuga describes a process of plastic deformation of the support structure through rolling formed. U.S. Patent No. 5,059,037 to Albert and U.S. Patent No. 5,161,896 to Hofling describe the floating of the bearing steel insert until it is placed by the reaction of the rolling element. U.S. Patent No. 5,217,308 to Schroeder discloses the joining of the bearing steel by the surface of couplings or by careful pressure adjustment. Therefore, it would be highly desirable to eliminate or reduce costly materials and the requirements of each of these manufacturing steps. Finally, it would be desirable to increase cheap materials and stages and reduce expensive materials and stages. Accordingly, it is an object of the present invention to provide an efficient and simplified manufacturing process which minimizes the costs associated with the manufacture of a bearing rail and the union of the bearing steel insert and at the same time provides the ability to optimize the quality of the linear motion bearing assembly manufactured. The objects and advantages of the invention are set forth in part herein and in part will be obvious from the same, or can be learned by the practice of the invention, which is carried out and is obtained by means of the instruments and combinations indicated in the appended claims. The invention consists of novel parts, constructions, arrangements, combinations, steps and improvements shown and described herein.

SUMMARY OF THE INVENTION? W In accordance with the present invention, a method is provided herein for producing a rail for use in a linear motion bearing assembly. The method includes the steps of forming a rail base member having at least one longitudinal groove and inserting a load bearing insert into the longitudinal groove. The load bearing insert may include parallel grooves to form load bearing tracks. This method simplifies the manufacture of the rail and avoids the need for a difficult and expensive polishing and hardening of the load bearing tracks directly on the rail. In addition, the method can include the steps of recessing surfaces of the base member to define the longitudinal groove, flexing the load bearing insert to fit the longitudinal groove, and tightening a portion of the base member to secure the load bearing insert. . The load bearing insert can cold strain to include the load bearing tracks therein. The base member can be extruded to include a pair of substantially vertical arms with the longitudinal grooves therein. This method provides a cheap and efficient manufacture, assembly and installation of the rail for use in a linear motion bearing assembly.

BRIEF DESCRIPTION OF THE DRAWINGS The appended drawings, to which reference is made and which constitute a part thereof, illustrate the preferred embodiments of the apparatus of the present invention and, together with the description, serve to explain the principles of the invention. Figure 1 is a perspective view with separate parts of a preferred embodiment of a rail for a linear motion bearing assembly manufactured in accordance with the present invention. Figure 2 is a perspective view of a rail of Figure 1 which is operated by a pinch roller to secure the insert. Figure 3a is an end view of the rail of Figure 1 being squeezed. Figure 3b is an end view of an alternative embodiment of the rail of Figure 1 that is tightened according to the present invention. Fig. 4 is an end view of a load bearing insert of the rail of Fig. 1. Fig. 5 is an end view of the load bearing insert and a base member of the rail of Fig. 1 before being tight. Figure 6 is an end view of the load bearing insert and the base member of the rail of Figure 1 after it has been tightened. Figure 7 is a perspective view of the bearing assembly of the assembled linear movement included in the rail of Figure 1.

DESCRIPTION PSTftT.T.ftTft PE T.AP MPT A method for producing a rail for use in a linear motion bearing assembly is provided herein. Referring now to the drawings in greater detail, and initially to Figure 1, a preferred embodiment of the rail 24 manufactured by the method described herein includes a pair of load bearing inserts 34 and a base member 26a substantially in the form U. The base member 26a is formed of a low cost material, such as machine grade aluminum, and is preferably extruded using known manufacturing techniques. Other suitable manufacturing techniques, such as, for example, the conventional polishing method, are also available to manufacture the base member 26a. The base member 26a includes a pair of substantially vertical arms 28a that are parallel and define an axial groove 30a along the longitudinal part of the base member 26a. This configuration provides an advantageous degree of flexibility for the vertical arms 28a with respect to the base member 26a. The longitudinal grooves 32a can be formed on opposite sides of the vertical arms 28a substantially parallel to the axial groove 30a. The load bearing inserts 34 are configured and dimensioned to fit within the longitudinal grooves 32a and define a portion of the load bearing tracks 38a. The load bearing inserts 34 are produced from a high quality bearing steel using known techniques that include, but they are not limited to cold-casting processes and subsequently cut to the desired length. The load bearing inserts 34 are hardened in line by known techniques such as, for example, heating and cooling induction. Each of the load bearing inserts 34 is preferably formed with a longitudinal relief 36 on an inner surface thereof. This longitudinal relief 36 provides the load bearing insert 34 with a degree of flexibility which improves its final assembly to the rail. The load bearing inserts 34 preferably have a substantially uniform cross-sectional thickness and include surfaces defining parallel load bearing tracks 38. The load bearing inserts 34 are mountable to the base member 26a by configuration of relative dimensions of the longitudinal grooves 32a and the load bearing inserts 34 so that the load bearing inserts 34 fit in the longitudinal grooves 32a with certain space. Optionally, the relative dimensions of the longitudinal grooves 32a and the load bearing inserts 34 can be configured so that the load bearing inserts 34 must be bent to fit in the longitudinal grooves 32a. With reference to Figure 2, the preferred tightening process in the current mode is presented. The load bearing inserts 34 are first inserted into the longitudinal grooves 32a of the base member 26a. The base member 26a acts as a support for the load bearing inserts 34 when a load is applied to the load bearing inserts 34. During the tightening process, a tightening roller 42a engages the rail 24 by tightening the flanges 40a on each side of the base member 26a simultaneously. The load bearing inserts 34 can also be temporarily or permanently deformed during tightening. In this embodiment, when the tightening roller 42a has passed, a given section of the base member 26a, the load bearing inserts 34 are flexed back, which leaves the load bearing inserts 34 in compression within the base member 26a. Alternatively, the tightening of the rail 26a can be carried out by sequential operation wherein each of the upper flanges 40a is tightened individually or sequentially. As an additional alternative, the tightening of the rail 24 can be carried out by a manual operation with hammering tools.

Figure 3a is an end view of the tightening roller 42a and the base member 26a in the tightening process when the load bearing inserts 34 are fixed to the base member 26a. As can be seen, the tightening roller 42a it is constructed to make contact with the base member 26a along the upper flanges 40a. The clamping roller 42a is further constructed with clamping surfaces 44a that control the deformation of the upper flanges 40a. The tightening roller 42a further has a central tab 46a which guides the tightening roller 42a along the base member 26a and ensures that the pattern of the roller is balanced. During the operation of the clamping roller 42a, the clamping surfaces 44a squeeze the upper flanges 40a on each outer surface 31a of the arm 28a simultaneously. Due to the low hardness and good formability of the extruded aluminum base member, it can be deformed, within limits, to form a new shape. In some cases, the deformation can be replaced with, for example, the return action by elasticity of the insert. This provides a robust connection between the components to ensure good coupling between the components when the base member 26a is subjected to elastic movement after the load has been removed.

Figure 3b is an end view of a pinch roller 42b configured for use with an alternative embodiment of the base member 26a. In this embodiment, a base member 26b includes a pair of substantially vertical arms 28b extending from the base member 26b and defining an axial groove 30b therebetween. The inner surface 31b of each arm 28b is provided with a load bearing insert that receives the slot 32b defining an upper flange 40b. The arms 28b are preferably flexible with respect to the base member 26b. In operation, the clamping roller 42b contacts the base member 26b along the upper flanges 40b. The clamping roller 42b includes clamping surfaces 44b that deform the upper flanges 40b. The tightening roller 42b also has a pair of extended walls 46b, which guide the tightening roller 42b along the arms 28b and ensure that the roller pattern is balanced. During a typical tightening operation, the clamping surfaces 44b tighten the upper flanges 40b on each inner surface 31b of the arm 28b simultaneously. As in the base member 26a of Figure 1, the deformation of the base member 26b can be supplemented by, for example, the elastic deformation action of the insert.

Figure 4 is an end view of the load bearing insert 34, and demonstrates the mechanics of the elastic deformation of the load bearing insert 34. The load bearing insert 34 can be formed into a spring to allow both the spring action as the bearing of a bearing load due to the hardness inherently required in the load bearing insert 34. As can be seen by comparison of the shape which is not deformed in continuous line with respect to the shape deformed with discontinuous lines, the part is free to flex along a horizontal axis by virtue of the shape and design of the longitudinal relief 36. This is the reaction that occurs as a result of the flexing of the load bearing insert 34 while inserted into the longitudinal slot 32a of the base member 26a or through the load applied by the tightening roller 42a through the base member 26. Figures 5 and 6 are provided for dem further detract the deformation of the vertical arm 28a, and more specifically the upper flange 40a in the tightening step. For clarity purposes, only vertical arm 28a is presented. Before the tightening process, as can be seen in Figure 5, the upper flange 40a is constructed so that there is a space between the load bearing insert 34 and the upper flange 40a. During the tightening process, the upper flange 40a is permanently plastically deformed to engage the load bearing insert 34. The arrows in Figure 5 indicate the approximate direction of the material flow. Again, the spring return effect of the upper flange 40a is compensated by the spring expansion of the load bearing insert 34. After the rolling process, the upper flange 40a has been permanently deformed downward, and the bearing insert load 34 has been securely fastened to vertical arm 28a, as shown in figure 6. With reference to figure 7, a fully assembled linear motion bearing assembly 20 is shown, in accordance with the present invention. The assembly includes a substantially an inverted U-shaped bearing bracket 22 configured and sized to move along the rail 24 on the load bearing tracks 38. The present embodiment shows the manufacture of a linear motion bearing assembly through the continuous rolling technique described above. Similar effects can be obtained by deforming the entire structure in a single loading application, or through intermittent load applications at linear frequencies given below the length of the base member 26a. In the same way, the bearing support 22 can be assembled in a similar manner. Insofar as it is not indicated in the foregoing, it will also be understood by those usually familiar with the art that any of the various embodiments described and illustrated herein may be further modified to incorporate features shown in other specific embodiments. The invention, in its broader aspects, is therefore not limited to the specific embodiments shown and described herein, but variations thereof may be made within the scope of the appended claims without departing from the principles of the invention and without sacrificing its main advantages. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims

REIVXNDICACIQNSS

1. A method for forming a rail for use in a bearing assembly for linear movement, characterized in that it comprises the steps of: forming an elongate base member having an insert mounting portion, the insert mounting portion having respective surfaces with at least one a longitudinal groove in them; elastically deforming a load bearing insert without causing substantial plastic deformation to the load bearing insert; inserting a load bearing insert elastically deformed on at least one longitudinal groove; and allowing the elastically deformed load bearing insert to regain its shape in contact with the insert mounting portion.

2. The method for forming a rail, according to claim 1, characterized in that it further comprises the step of tightening a portion of the insert mounting portion to secure the load bearing insert.

3. The method for forming a rail, according to claim 1, characterized in that the load bearing insert is flexible and the insertion step includes the step of flexing the load bearing insert to fit it into at least one longitudinal groove .

4. The method for forming a rail, according to claim 1, characterized in that it further comprises the step of lowering the surfaces to define at least one longitudinal groove.

5. The method for forming a rail, according to claim 1, characterized in that: the elongated base member has a pair of substantially vertical arms, the vertical arms have respective surfaces with at least one longitudinal groove therein.

6. The method for forming a rail, according to claim 5, characterized in that it further comprises the step of tightening a portion of the vertical arm adjacent to at least one longitudinal slot to secure the load bearing insert.

7. The method for forming a rail, according to claim 5, characterized in that it further comprises the step of cold-extracting the load bearing insert having at least one load bearing track therein.

8. The method for forming a rail, according to claim 5, characterized in that the forming step comprises the step of extruding the base member so that the vertical arms are flexible.

9. The method for forming a rail, according to claim 5, characterized in that it further comprises the step of lowering the surfaces of the vertical arms to define at least one longitudinal groove and at least one upper flange.

10. The method for forming a rail, according to claim 5, characterized in that it comprises the additional steps of: extruding the elongate base member having a pair of substantially vertical arms, having respective outer or inner surfaces, with a pair of grooves longitudinals recessed therein and upper flanges, the vertical arms are flexible with respect to the base member; providing a pair of flexible load bearing inserts having outer or inner surfaces, the outer surfaces defining a plurality of parallel grooves to form load bearing tracks, the inner surfaces defining longitudinal reliefs to improve flexibility; flexing the load bearing inserts to fit them within the recessed longitudinal grooves; and tighten the upper flanges to secure the load bearing inserts.

11. The method for forming a rail, according to claim 10, characterized in that the tightening step includes tightening the pair of upper flanges simultaneously to secure the load bearing inserts.

12. The method for forming a rail, according to claim 10, characterized in that the load bearing inserts fit within the recessed longitudinal grooves after bending, without causing substantial plastic deformation thereto.

13. A method for forming a rail, for use in a bearing assembly for linear movement, characterized in that it comprises the steps of: extruding an elongated base member having a pair of substantially vertical arms having respective inner surfaces with a pair of longitudinal grooves lowered therein and a pair of upper flanges, the vertical arms are flexible with respect to the base member; providing a pair of flexible load bearing inserts having outer and inner surfaces, the outer surfaces defining a plurality of parallel grooves to form tracks of the load bearing, the inner surfaces defining longitudinal reliefs to improve flexibility; place the load bearing inserts in the recessed longitudinal grooves; and tightening the upper flanges to cause elastic deformation of the load bearing inserts without causing substantial plastic deformation thereto to secure the load bearing inserts.

14. The method for forming a rail, according to claim 13, characterized in that the tightening step includes tightening the pair of upper flanges simultaneously to secure the load bearing inserts. F-SJMEW E THE INVENTION A method for forming a rail having an elongated base member (26A) and a load bearing insert (34) is disclosed. The method includes forming a base member having surfaces with at least one longitudinal groove (32A) and inserting the load bearing insert (34) into the longitudinal groove (32A). By inserting the load bearing insert it can be carried out by flexing the load bearing insert to fit within the longitudinal groove. The surfaces (40A) of the base member adjacent to the longitudinal groove can be subsequently tightened to secure the load bearing insert.