Linear motion guide unit with separator between any two adjoining rolling elements

• US 20030118256A1
• Filed: 03/07/2002
• Published: 06/26/2003
• Est. Priority Date: 12/25/2001
• Status: Active Grant

• Current Assignee: Nippon Thompson Company Limited
• Original Assignee: Nippon Thompson Company Limited
• Inventors: Ishihara, Toyohisa
• Granted Patent: US 6,682,218 B2
• Time in Patent Office: Days
• US Class Current: 384/45
• CPC Class Codes: F16C 29/0609 of the ends of the bearing body or carriage where the rolling elements change direction, e.g. end caps
• CPC Class Codes: F16C 29/063 with a bearing body, e.g. a carriage or part thereof, provided between the legs of a U-shaped guide rail or track
• CPC Class Codes: F16C 33/3706 with concave surfaces conforming to the shape of the rolling elements, e.g. the spacing bodies are in sliding contact with the rolling elements

Abstract

A linear motion guide unit is disclosed in which a separator is made to fit over or embrace any adjacent rolling element, thereby realizing quiet operation and wear-resistance, with even under high-speed, high-cycle sliding motion. The separator has a round outside peripheral surface, and forward and aft end faces that are made concave to fit over the associated rolling elements. An end cap is made up of a spacer part having a lug to provide a radially inside curved surface of a turnaround, and a major part to provide a radially outside curved surface of the turnaround when mounted on a carriage through the spacer part. Cut in the radially inside curved surface on the lug is a gutter for relief, which extends circumferentially ilk along the center of the radially inside curved surface on the lug, thereby allowing the separator to travel through the turnaround without any interference with the radially inside curved surface of the turnaround.

Claims

1. A linear motion guide unit comprising;

a track rail having a first raceway groove extending lengthwise thereof and a slider arranged for movement relatively to the track rail by virtue of more than one rolling element, the slider being comprised of a carriage made thereon with a second raceway groove confronting the first raceway groove on the track rail to define a raceway between them, where the rolling elements are allowed to run through there, and also made therein with a return passage allowing the rolling elements to run through there, end caps fastened on forward and aft ends of the carriage, one to each end, and each made therein a turnaround that connects the raceway with the return passage to allow the rolling elements to turn round there, and more than one separator interposed between any two adjoining rolling elements to travel together with the rolling elements, wherein the separator has a round outside peripheral surface, and forward and aft end faces that are made concave to fit over the associated rolling elements, and wherein the turnaround formed in the end cap has a radially inside curved surface where a gutter for relief is cut in a way extending circumferentially of the turnaround, thereby allowing the separator to travel through the turnaround without any interference with the radially inside curved surface of the turnaround.

2. A linear motion guide unit constructed as defined in claim 1, wherein the end cap is comprised of a spacer part having a lug to provide the radially inside curved surface of the turnaround when the spacer part is fastened on the associated end of the carriage, and a major part to provide a radially outside curved surface of the turnaround when mounted on the carriage through the spacer part.

3. A linear motion guide unit constructed as defined in claim 2, wherein the spacer part integral with the lug is joined firmly to the major part with only fitting in a recess formed in the major part, whereby the turnaround is completed.

4. A linear motion guide unit constructed as defined in claim 2, wherein the gutter for relief is cut in the lug in a way extending circumferentially along a center of the radially inside curved surface of the turnaround.

5. A linear motion guide unit constructed as defined in claim 2, wherein the spacer part has positioning pins that protrude from the rears of the lugs, which confront the carriage, while the carriage is made on the end face thereof with positioning holes that are bored in opposition to the positioning pins, whereby only fitting the positioning pins into the positioning holes on the end face of the carriage is sufficient to make sure of connection of the spacer part to the carriage.

6. A linear motion guide unit constructed as defined in claim 2, wherein the major part of the end cap has outside joint tongues each of which is adapted to fit into any associated open end of the return passage in the carriage, while the spacer part has inside joint tongues each of which is also allowed to fit into any associated open end of the return passage in the carriage, and wherein the outside and inside joint tongues are mated together in alignment with each other to be connected to the associated return passage.

7. A linear motion guide unit constructed as defined in claim 6, wherein a tubular member of sintered resinous material having cellular texture is nested inside the return passage in the carriage to extend between the lengthwise opposing joint tongues and the tubular member can contain therein lubricant.

8. A linear motion guide unit constructed as defined in claim 1, wherein the concaved surface is made to have a radius of curvature, which is just a little larger than that of the rolling element.

9. A linear motion guide unit constructed as defined in claim 1, wherein the separator is made as thin as possible in thickness left between the concaved surfaces arranged back to back with one another, so that the adjoining rolling elements are separated a little bit away from each other.

10. A linear motion guide unit constructed as defined in claim 1, wherein the separator is made rounded at forward and aft circumferential edges where the outside periphery merges with the concaved surfaces, so that the rounded edges would help make sure of smooth travel of the separator throughout the ball-recirculating circuit even if there were any discrepancy in position between the carriage and the end cap to cause some misalignment between either the load-bearing raceway or the return passage and the associated turnaround for the ball-circulating circuit.

11. A linear motion guide unit constructed as defined in claim 1, wherein the track rail has first raceway grooves on the lengthwise sides thereof, one to each side, while the slider fits over and conforms to the track rail for sliding movement relatively to the track rail by virtue of the rolling elements and the separators.

12. A linear motion guide unit constructed as defined in claim 1, wherein the track rail has a pair of lengthwise side walls spaced sidewise apart from and connected with each other, and also made on their sidewise opposing sides with the first raceway grooves, while the slider is accommodated in a guide channel between the side walls of the track rail for sliding movement lengthwise the track rail.