EP0457858A4

EP0457858A4 - Single motor robot

Info

Publication number: EP0457858A4
Application number: EP19900911018
Authority: EP
Inventors: Norman N. Fender
Original assignee: Graco Robotics Inc
Current assignee: ABB Trallfa Robot AS
Priority date: 1989-06-23
Filing date: 1990-06-21
Publication date: 1992-04-22
Also published as: CA2019569A1; FR2677421A1; EP0457858A1; WO1991000555A1

Abstract

A low cost robot (10) is constructed using a constant speed motor (12) which drives a gear box (14) having two output shafts (16, 18) which rotate in opposite directions. Each of the shafts (16, 18) has a brake disk (20) thereon and independently rotatable about the shaft (16, 18) is a brake caliper (26, 54) assembly which is in turn connected via a chain (42, 58) to a tool bearing member (48) to be moved. By variously activating one, the other or both of the calipers (26, 54), position and speed of the tool arm 50) can be exactly controlled. More than one arm or axis may be controlled off of the motor (12) leading to further economies of manufacture.

Description

SINGLE MOTOR ROBOT

BACKGROUND OF THE INVENTION

In recent years, robots have become very popular in industrial manufacturing situations. Such devices lead to decreased labor cost as well as improved quantity resulting from repeatability of performance. Robots in general and in particular electric robots tend to be quite expensive as such machines typically require a motor for each axis of movement in the machine. Furthermore, the motors required tend to be quite expensive as they require high start up torque and quick response.

In the early stages of the industrial revolution, it was common to have a central shaft running through a factory which would be powered by a water mill or steam. In such situations, a number of pulleys were located along the shaft and belts which ran about those pulleys would power individual machines. The belts were either engaged or disengaged to drive the machine.

It is therefore an object of this invention to provide an improved industrial robot which can be manufactured for substantially less cost than prior art devices and which will run for long periods of time without maintenance. SUMMARY OF THE INVENTION

A simple constant speed motor drives a gear box which has two output shafts which rotate in opposite directions. Each output shaft has a traditional automotive type brake disk located thereon. Attached and rotatable about the shaft is a caliper or gripping member which is in fact independently rotatable from the shaft itself and from the brake disk.

The caliper is connected to a sprocket which drives a chain or other connecting member which is attached to me tool bearing member or robot arm. Since there is a caliper and sprocket mechanism on each shaft, selective activation of the caliper will cause the caliper mechanism to grip the rotating break disk and thereby rotate there along transferring the motion through the chain to the tool bearing member. By activating one, the other or both of the brake calipers, the exact positioning and speed of the tool bearing member may be controlled.

These and other objects and advantages of the invention will appear more fully from the following description made in conjunction with the accompanying drawings wherein like reference characters refer to the same or similar parts throughout the several views.

A BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view of the instant invention.

Figure 2 is a sectional view taken along line 2-2 of Figure 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The instant invention is shown in general in Figure 1 and is generally designated 10. The robot 10 is comprised of a motor 12 which may be a relatively inexpensive constant speed type motor . The output of motor 12 is connected to a gear box 14 having first and second output shaft 16 and 18 respectively.

Attached to first shaft 16 is a brake disk 20 which may be a typical automotive type brake disk which is typically used in disk brakes. It is attached as shown with a key 22 which is held in place by set screw 24. Of course any number of attachment methods may be used as desired and the illustration is only for purposes of convenience.

A caliper 26, also of the typical automotive brake type, is attached to mounting bracket 28 by means of bolts 30. Bracket 28 is mounted to shaft 16 but separated therefrom by a bearing member 32 which allows bracket 28 to rotate independently from shaft 16 and disk 20. Attached to bracket 28 is a sprocket member 34 by means of bolts 36. Thus, sprocket 34 rotates in unison with bracket 28 and caliper 26. An end cap 38 is held in place by bolt 40 and helps retain bearing assembly 32 and bracket 28 on the end of shaft 16. A chain or belt 42 runs around the outside of sprocket 34 and in turn engages sprocket 44 on shaft 46 which carries tool bearing member 48 having tool 50 thereon. Shaft 46 rotates in bearing 47.

Similarly, second brake disk 52 is mounted on second shaft 18 and is controllably gripped by second caliper 64 which is mounted to sprocket 56, caliper 54 and sprocket 56 both rotating independently about shaft 18 relative to brake disk 52. In turn, chain or belt 58 runs about sprocket 56 and sprocket 60. Sprocket 60 is affixed to shaft 46 along with sprocket 44.

Servo valve 62 is controlled by a conventional robot intelligent controller 64. Flexible lines 66 and 68 lead to calipers 26 and 54 respectively and allow the servo valve 62 to variously energize the brake pads 26a of caliper 26.

Of course it can be appreciated that the scheme and mechanism shown in Figure 1 can be used to operate multiple axes and indeed even multiple robots. First and second shafts 16 and 18 could each be provided with a plurality of brake disks and caliper assemblies, each set of which could be used to control a particular axis whether within the same robot itself or within different robots depending on the desires of the system designer. While the term tool bearing member has been used herein, it should be appreciated that the member being moved may in fact be another arm of the robot having yet another axis at the end thereof which may control the tool itself.

It is contemplated that various changes and modifications may be made to the robot without departing from the spirit and scope of the invention as defined by the following claims.

Claims

WHAT IS CLAIMED IS:

1. A robot for controlling a rotatable tool-bearing member, said robot comprising:

generally parallel first and second shafts rotating in opposite directions relative to one another;

first gripping means for controllably gripping said first shaft, said first gripping means being connected to rotate said tool- bearing member in a first direction; and

second gripping means for controllably gripping said second shaft, said second gripping means being connected to rotate said tool bearing member in a second direction opposite said first direction.

2. The robot of claim 1 further comprising means for controlling said first and second gripping means.

3. The robot of claim 2 wherein said controlling means comprises a servo valve associated with each said gripping means.

4. The robot of claim 1 wherein each said gripping means comprises a brake mechanism.

5. The robot of claim 1 wherein said first and second shafts are continuously driven by a constant speed motor.

6. The robot of claim 1 wherein said tool bearing member rotates around an axis parallel to said first and second shafts.

7. The robot of claim 1 further comprising: a motor; and

a gearbox having an input, said motor driving said gearbox input and said first and second shafts being driven by said gearbox

8. The robot of claim 1 said gripping means comprising;

a brake disk attached to each said shaft; and

a caliper mounted coaxially with and independent rotatable about each said shaft.

9. The robot of claim 8 further comprising a chain connecting said caliper and said tool bearing member.

10. The robot of claim 1 wherein said first and second gripping means comprise an axis set of gripping means and wherein the plurality of axis sets of gripping means are located on said first and second shafts, each set of axis gripping means controlling a rotatable tool bearing member.