GB2098109A - Finishing apparatus for workpieces - Google Patents

Abstract

The apparatus comprises a finishing chamber for a mixture 12 of workpieces W and finishing media M. A movable flap 16 is provided for directing the mixture from the chamber to a sieve 15 above the chamber floor 14. The flap includes a flexible sheet 27 which extends upwardly to overlie the sieve and prevent workpieces or finishing media becoming jammed in a gap 28 between the sieve and a plate 17 of the flap. <IMAGE>

Description

SPECIFICATION Finishing apparatus for workpieces The invention relates to finishing apparatus for workpieces.

Various types of finishing machines have been proposed hitherto and the invention is particularly concerned with finishing machines of the vibratory type in which a mixture of workpieces and abrading media are vibrated together within a finishing chamber.

In such machines it it common practice to separate the workpieces from the abrasive medium by directing the mixture to a separating screen leading off the chamber. In order to do that the mixture may be arranged to move up a dam in the chamber and on to a movable member pivotally mounted on the chamber wall. The member is often in the form of a pivotally mounted flap which engages the top of the dam and directs the mixture from the top of the dam to the screen. Once the separating step is complete, the flap is pivoted clear of the dam.

Several types of flap have been produced but suffer from certain disadvantages. One particular disadvantage is the possibility of finishing media becoming trapped between the upper end of the flap and the adjacent end of the screen thereby impeding pivotal movement of the flap. An object of the invention is to provide a finishing device in which the foregoing disadvantage is reduced.

According to the invention there is provided finishing apparatus for workpieces comprising a finishing chamber for a mixture of workpieces and finishing media, a movable member for directing the mixture from the chamber towards a surface above the floor of the chamber, and an element mounted for flexing and arranged to extend between an upper portion of the member and the said surface so that the mixture will pass over the element as it travels towards the surface.

Preferably the element comprises a sheet of flexible material. In such a case the flexible sheet may be mounted on the member to form a flap having a flexible upper end which overlies a portion of the said surface above the floor of the chamber.

Preferably the flap is pivotally mounted on a wall of the chamber and includes a rigid shoe engageable with a floor of the finishing chamber or a dam on said floor and a rigid plate extending upwardly from the shoe and which is rotatably fast with pivoting means for the flap, a lower portion of the flexible sheet being secured to the shoe and an upper portion of the sheet being arranged to overlie the rigid plate in such a way that the sheet can flex upwardly relative to the plate.

The invention also includes a flap for directing a mixture of workpieces and finishing media from a finishing chamber of finishing apparatus to a surface above the finishing chamber, the flap comprising a member arranged to be movably mounted on the apparatus for directing the mixture towards said surface and a flexible element extending from the member so that, in use, the flexible element will overlie a portion of the surface. The flap may be formed as a moulding by inserting the rigid plate into a mould together with the flexible sheet, introducing settable material into the mould so as to cover portions of the rigid plate and flexible sheet and allowing the material to set to form the shoe and to bond to the flexible sheet and rigid plate.

A finishing device in accordance with the invention will now be described by way of example with reference to the accompanying drawings in which: Figure lisa plan view of a vibratory finishing machine in accordance with the invention, Figure 2 is a cross-section of the machine shown in Figure 1 on the line 11 - 11 in Figure 1, Figure 3 is an underplan view to a smaller scale of a flap for the machine of Figures 1 and 2, and Figure 4 is a cross-section through a mould for use in forming the flap.

In Figure 1, the machine comprises an annular tank 10 defining a finishing chamber 11. The chamber receives a mixture 12 (Figure 2) of workpieces W and suitable finishing media M and the tank is mounted on means (not shown) which imparts vibratory movement to the tank so that the finishing media abrades or polishes the workpieces. The vibratory movement causes the mixture to move around the chamber. A dam 13 is provided on a floor 14 of the chamber and the mixture travels up one side 13a of the dam and down the other side 1 3b as it travels around the chamber.

When finishing of the workpiece is complete, it is necessary to separate the workpiece W from the finishing media M and a separating screen 15 is provided for that purpose. In order to lead the mixture from the chamber 11 to the screen 15, a flap 16 is provided.

The flap 16 includes a rigid metal plate formed with apertures 17a (Figure 3) to enable itto be screwed to a flat surface 18 formed on a metal shaft 19. The shaft 19 is pivotally supported by inner and outer side walls 20,22 of the tank 10 and the radially outer end of the shaft is secured to a handle 23. The plate 17 is bonded to a plastics shoe 24 is a manner described below. The shoe has an oblique lower end 25 which is movable into engagement with a ridge surface 26 of the dam. A flexible plastics sheet 27 is bonded to an upper portion of the shoe 24 between the shoe and the plate 17. The sheet 27 lies on the plate 17 and extends across a gap 28 which is defined between the upper end of the plate 17 and the adjacent edge of the screen 15.When the flap occupies an inoperative position shown in broken lines in Figure 2, the sheet 27 remains in engagement with the screen and flexes upwardly.

In use, the flap 16 is pivoted downwardly from the broken line position to the full line position in Figure 2 when it is desired to separate the workpiece W from the media M. The mixture 12 then travels up the side 13a of dam 13, along the upper surface of shoe 24, along the flexible sheet 27 and on to the screen 15. The media M falls through the screen leaving the workpieces W behind. The flexible sheet 27 prevents any media jamming in the gap 28.

Reference is now made to Figure 4. To form the flap, the plate 17 is abraded on both sides over a distance D and is positioned in a mould 30. The flexible sheet 27 is arranged between the plate 17 and a spacer 32 and the assembly is clamped by jaws 33 to an extension 34 of the mould. Uncured plastics material is then poured into the mould to form the shoe 24 so that it covers substantially the whole of the abraded surfaces of the plate 17 and a lower portion of the sheet 27. The plastics is then cured so that it bonds to the plate and the flexible sheet. As shown in Figure 3, the shoe covers the edge of the plate 17 and sheet 27. The plastics forming the shoe 24 is preferably 85/90 shure polyurethane and that forming the flexible sheet 27 is preferably 65/70 shure polyurethane. The section of the sheet 27 indicated at S is not bonded to the plate 17 so that the sheet can flex upwardly as shown in broken lines in Figure 2.

The term "mounted for flexing" used herein includes a pivotal type mounting which will allow flexible plate 27 to be replaced by a rigid plate hingedly connected to the plate 17.

Although specific reference has been made to a dam, the flap 16 may be arranged to lead the mixture directly from the floor 14; the dam being omitted.

Instead of providing a flexible element on the plate 17, the element could be mounted on the seive or a surface upstream thereof and extend to the plate 17 so as to cover any gap between the plate and the seive or said surface.

Claims (10)

1. Finishing apparatus for workpiece comprising a finishing chamber for a mixture of workpiece and finishing media, a movable member for directing the mixture from the chamber towards a surface above the floor of the chamber, and an element mounted for flexing and arranged to extend between an upper portion of the member and the said surface so that the mixture will pass over the element as it travels towards the surface.

2. Finishing apparatus according to claim 1 in which the element comprises a sheet of flexible material.

3. Finishing apparatus according to claim 2 in which the flexible sheet is mounted on the member to form a flap having a flexible upper end which overlies a portion of the said surface above the floor of the chamber.

4. Afinishing device according to claim 3 in which the flap is pivotally mounted on a wall of the chamber and includes a rigid shoe engageable with a floor of the finishing chamber or a dam on said floor and a rigid plate extending upwardly from the shoe and which is rotatably fast with pivoting means for the flap, a lower portion of the flexible sheet being secured to the shoe and an upper portion of the sheet being arranged to overlie the rigid plate in such a way that the sheet can flex upwardly relative to the plate.

5. A flap for directing a mixture of workpieces and finishing media from a finishing chamber of finishing apparatus to a surface above the finishing chamber, the flap comprising a member arranged to be movably mounted on the apparatus for directing the mixture towards said surface and a flexible element extending from the member that, in use, the flexible element will overlie a portion of the surface.

6. A flap according to claim Sin which the flexible element comprises a sheet of flexible material.

7. A flap according to claim 6 in which the member includes a rigid shoe connected to a rigid plate having means thereon for pivoting the member, said shoe being connected to a portion of the flexible sheet so as to leave a further portion overlying the rigid plate so that it can flex relative to the plate.

8. A flap according to claim 7 which is formed as a moulding by inserting the rigid plate into a mould together with the flexible sheet, introducing settable material into the mould so as to cover portions of the rigid plate and flexible sheet and allowing the material to set to form the shoe and to bond to the flexible sheet and rigid plate.

9. Finishing apparatus for workpieces constructed and arranged substantially as described herein with reference to the accompanying drawings.

10. Aflap for use in finishing apparatus constructed and arranged substantially as described herein with reference to the accompanying drawings.