GB2250935A

GB2250935A - Automatic sprayer apparatus

Info

Publication number: GB2250935A
Application number: GB9026283A
Authority: GB
Inventors: Ian David Marshall
Original assignee: MARSHALL WELDED STEEL Ltd
Current assignee: MARSHALL WELDED STEEL Ltd
Priority date: 1990-12-04
Filing date: 1990-12-04
Publication date: 1992-06-24
Anticipated expiration: 2010-12-04
Also published as: GB2250935B; GB9026283D0

Abstract

An apparatus for automatically spraying an article 25 has an arm 10 rotatable by a motor 15 about an axis. A carriage 17 is movable radially of the arm 10 by a fixed cam form 23 and carries a spray device 20. The cam form 23 conforms generally to the surface of the article 25 which is of regular shape and is, in use, positioned so that its axis is aligned with the axis of rotation of the arm 10. <IMAGE>

Description

AUTOMATIC SPRAYER APPARATUS Where a sprayed material, typically paint, is to be applied to objects having relatively large surface areas, the use of a program controlled sprayer can result in unacceptably long spraying times.

This invention relates to an apparatus for spraying an article having a regular shape. An article of regular shape is defined for the purpose of the invention as being one which has a surface, or surfaces, which are defined by movement of a fixed contour about an axis, such that inclination of the contour to a plane normal to that axis is constant. It will be realised that such regular shapes include not only cylinders and prisms, but also cones, pyramids and hourglass forms.

According to the invention there is provided an automatic spraying apparatus comprising a support arm, means for rotating said arm about an axis, a cam form fixed relative to the axis of rotation of said arm, a carriage slidable radially of said arm and constrained to follow said cam form as said arm is rotated, a spray device supported on said carriage and directed generally radially of said arm, and means for locating an article of regular shape, as herein defined, so that the axis of said article is aligned with the rotational axis of said arm.

An embodiment of the invention will now be described by way of example only and with reference to an apparatus for spraying the outer surfaces of a stack of pallets.

In the drawings: Figure 1 is an elevation of a spraying apparatus, Figure 2 is a view of arrow 2 in Figure 1, and Figure 3 is a diagram showing rotational speeds of a spray arm forming part of Figure 1, during a single spraying cycle.

As shown in Figure 1 a rotor 10 is supported by rollers 11 in a structure 12 which is mounted above the floor 13 of a spraying station. The structure 12 also carries a drive shaft 14 for the rotor 10, and a motor 15 which is coupled to the shaft 14 by means of a non-slipping belt and pulley arrangement 16. A carriage 17 is carried on rollers 18 within one arm of the rotor 10 and includes a portion 19 which extends vertically downwards and on which a plurality of sprayers 20 are mounted at equally spaced intervals. The carriage 17 also includes an upwardly extending portion 21 on which is carried a cam follower roller 22. The roller 22 engages a cam form provided by the sides of a channel 23 carried on the structure 12, and between which the roller 22 is located.

A roller chain conveyor 24 is supported on the floor 13 for carrying a succession of workpieces 25 to a position in which they are to be sprayed. In the present example each of the workpieces 25 comprises a plurality of pallets which are stacked vertically upon each other and whose outside surfaces are to be sprayed. Each workpiece 25 thus has the shape of a rectangular prism, a plan view of the workpiece 25 being shown in Figure 2. Each workpiece 25 thus has a vertical axis XX and its shape can be considered as being generated by a straight line contour Co which moves about the axis XX so as to maintain a constant angle of 900 with a plane normal to the axis XX.

In use the alignment of each workpiece 25 on the conveyor 24 is determined in accordance with the known configuration of the cam form 23. Each workpiece 25 is moved by the conveyor 24 until the axis XX of the workpiece is aligned with the axis of the shaft 14. The cam form 23 is such that the sprayers 20 move on a path indicated at P in Figure 2, and are thereby maintained at a constant distance from the faces of the workpiece 25.

In order that excessive material shall not be sprayed on, or adjacent the vertical edges of the workpiece 25 the rotor 10 is driven faster adjacent the edges than across the workpiece faces. Figure 3 shows angular speeds V of the rotor 10 plotted over angular distance &commat;0 forfor a complete spraying cycle. It will be seen that rotational speed is increased over distances H-A, B-C, D-E and F-G, so that the amount of material deposited on the vertical edges is not substantially greater than that on the faces.

It will be apparent that an apparatus according to the invention may be used to spray an inside surface, or surfaces, if the portion 19 carrying the sprayers 20 can also be lowered and retracted. It will also be apparent that the sprayers 20 may be mounted on the portion 19 so as to maintain a constant distance from the face, or faces, of a workpiece of any regular shape, that is one in which the generating contour Co, and its angle to the horizontal, remains constant.

Claims

1. An automatic spraying apparatus comprising a support arm, means for rotating said arm about an axis, a cam form fixed relative to the axis of rotation of said arm, a carriage slidable radially of said arm and constrained to follow said cam form as said arm is rotated, a spray device supported on said carriage and directed generally radially of said axis of rotation, and means for locating an article of regular shape, as herein defined, so that the axis of said article is aligned with said axis of rotation.

2. An apparatus as claimed in claim 1 in which said arm forms part of a rotor which is supported at its periphery on a relatively fixed structure.

3. An apparatus as claimed in claim 1 or claim 2 in which said carriage includes a portion which extends in a direction generally parallel to said axis of rotation, said spray device being mounted on said portion.

4. An apparatus as claimed in any preceding claim in which said spray device comprises a plurality of sprayers.

5. An apparatus as claimed in any preceding claim in which said spray device is directed radially inwardly.

6. An apparatus as claimed in any preceding claim which includes means for varying the speed of rotation said arm in accordance with the shape of said article, so that sprayed material is deposited substantially evenly thereover.

7. An automatic spraying apparatus substantially as hereinbefore described with reference to the accompanying drawings.