Browse Prior Art Database

Precision Transfer Machine

IP.com Disclosure Number: IPCOM000037086D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 3 page(s) / 61K

Publishing Venue

IBM

Related People

Watts, KW: AUTHOR

Abstract

This article describes a transfer mechanism that provides accurate workpiece location and repeatability on the order of 0.0001 inch while providing the workpiece carrier an additional degree of freedom of precision movement within the workstation. The transfer mechanism consists of an air bearing and magnetic circuit combination which allows the carriers to be easily removed from the precision guide and restarted at the beginning for recirculating the carriers.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

Precision Transfer Machine

This article describes a transfer mechanism that provides accurate workpiece location and repeatability on the order of 0.0001 inch while providing the workpiece carrier an additional degree of freedom of precision movement within the workstation. The transfer mechanism consists of an air bearing and magnetic circuit combination which allows the carriers to be easily removed from the precision guide and restarted at the beginning for recirculating the carriers.

Transfer systems are used extensively in manufacturing operations to convey a workpiece from operation to operation. Typically, the workpiece is mounted on a pallet or other suitable carrier that is conveyed by belt, chain or rollers to the workstations of a manufacturing process. At each workstation, the workpiece is accurately positioned relative to the workhead by the insertion of location pins

(Image Omitted)

into bushings. The positioning repeatability of this method is limited from 0.001 inch to 0.002 inch. Moreover, this pin-in-bushing method eliminates freedom of movement of the carrier within the workstation.

The mechanism disclosed herein is illustrated in Figs. 1 and 2. Fig. 1 is an isometric view of a two-station machine, and Fig. 2 is a side view of the machine. In practice, the machine can be implemented with any number of stations and multiple carriers per system. It includes a workpiece carrier 1 which conveys a workpiece 8 from station to station. The carrier is shown in its simplest form. But, as with any carrier in any transfer system, the carrier can be easily adapted to the workpiece. The workpiece carrier 1 is guided through the machine by precision guide rail 2, upper guide rail 11 and lower guide rail 10.

An air bearing and magnetic gap 3 exists between the precision guide rail 2 and the workpiece carrier 1 so that a thin film of air separates the two while a magnetic circuit holds them together. The straightness of the horizontal component of travel is controlled by the precision guide rail 2 and the attainable straightness is comparable to any standard air bearing slide. Straightness accuracies of 0.0001 inch in 12 inches are common, and higher accuracies are attainable.

The typical air bearing linear slide is configured so that the carriage is supported on four sides of the guide rail by an air film. This arrangement is impractical for a transfer system because the carriages or carriers must be recirculated, and this requires removing the carrier from one end of the guide rail and starting it back on the other end. This is impractical due to the close fit between the carriage and the rail. Other precision linear motion devices such as linear ball bushings, crossed roller slides or linear rails, for...