GB2081146A - Deburring of Sand Cores - Google Patents

Abstract

Apparatus for deburring sand cores for casting comprising a holder (5) for the sand core (6) and a device (8), vertically movable above the core holder, from which loosely hang a number of strands (9). Each strand comprises a large number of solid elements (10) which are connected to each other in such a manner that they are movable relatively to one another. The vertically-movable device (8) is connected to a hydro-pulser (11) in such a manner that a burr can be removed from a sand core held in the core holder (5) by the strands which oscillate with the vertically-oscillating device. <IMAGE>

Description

SPECIFICATION Deburring of Sand Cores This invention relates to an apparatus for deburring sand cores used in casting. and a method of deburring sand cores using such apparatus.

It has already been proposed to remove burrs from cores manually by grinding or abrading. Only sand cores having burrs that can be reached by the grinding or abrading disc are suitable for this method. This may result in great handling expenses and considerable operating costs.

Deburring by means of a template in the case of sand cores having burrs formed substantially in one plane, is described for example, in German Patent Specification No. 41 6 782. This expensive template, which is adapted to suit the particular peripheral shape of the sand core, is stroked manually or mechanically over the sand core so as to remove the burr projecting beyond the periphery.

Since burrs that are otherwise spatially disposed on the sand core cannot be dealt with in this method, such a template can be used only for limited purposes.

German Patent Specification No. 1 9 1 8 007 discloses a method of deburring sand cores made of multi-part moulds, in which method material which can flow is directed under the effect of gravity on to the sand cores that are to be deburred. A disadvantage of this system is the cost of the means for separating the material used from the sand, as well as for returning that material to its original position, and the associated space requirements in machines for the peening and shot-blasting of cores.

German Offenlegungschrift No. 27 31 802 describes a method of deburring sand cores wherein granular material is flung against a sand core which is mounted to rotate. The apparatus proposed for the purpose enables the material to be flung with varying degrees of force at the sand core that is to be deburred.

For this purpose of deburring by this method, the sand cores must have a certain basic strength.

In this method, which is thus suitable only for relatively solid said cores, a further disadvantage is the need for special core holders which result in high capital costs.

An aim of the present invention is to provide apparatus for carrying out a method of deburring sand cores in an economical manner and substantially without damage to the surface of the cores, which apparatus is of simple construction and is easy to operate.

Accordingly, the present invention is directed to apparatus for deburring sand cores comprising a holder for a sand core and a device which is vertically movable above the core holder and from which loosely hang a number of strands each comprising a large number of solid elements which are connected to each other in such a manner that they are movable relatively to one another, the device being connected to a verticaloscillation generator in such a manner that a burr can be removed from a sand core held in the core holder bv the strands which oscillate with the Xertícallyosclllating device.

The invention also extends to a method of deburring sand cores using such apparatus.

With such apparatus, the loosely-hanging strands, which are drawn past the sand core during the upward and downward movements, tear off the projecting burr on the core.

Substantially damage-free inward rounding of the areas at which the core burr is broken off, and avoidance of damage to the surface, may advantageously result from the use of a large number of strands.

A simple construction, and therefore economically-operated apparatus for deburring sand cores, can be obtained in this way. It is economically advantageous because it can deal with sand cores of variousshapes. If a suitable frequency and/or amplitude of the oscillating strands is or are selected, it is also possible, to a certain extent, to remove burrs from undercut areas of a sand core.

Preferably, each strand comprises spherical elements which are spaced from each other, and oscillations of the vertical-oscillation generator of different frequencies and/or amplitudes can be selected, it being possible to alter the frequency and/or amplitude during deburring. It is then possible, using the elements of a strand, which may be of one size and spaced from each other to carry out deburring on a wide variety of sand cores in an optimum manner, while providing a free choice as regards the frequency and/or amplitude of the oscillating strands. With the further feature of varying frequency and/or amplitude during the deburring operation, it becomes possible to change over from an initial "roughing" procedure to a "smoothing" procedure.

If the core holder is designed to rotate or swivel the sand core, it is possible to deburr the entire sand core in an efficient manner, so that the quality of the castings is considerably improved.

In one embodiment of the present invention, the level of the device above the core holder can be adjusted by a servo-motor, it being possible for the servo-motor and the vertical oscillation generator to form one unit such as a hydropulser, and the unit comprising the servo-motor and the vertical oscillation generator is programmecontrolled for specific sand cores, the unit being switched on via a time-delay switch arranged in the core holder. This makes possible an "all-round deburring" which proceeds automatically with the aid of a programmed control system, and only the insertion and removal of the sand core need be carried out by hand.

Thus the present invention can provide apparatus which involves very little manipulation and can relieve the operator of fatigue. It can be integrated in an installation for the preparation of sand cores without any great cost as regards construction and personnel. Furthermore, the quality of the castings obtained with the sand cores deburred with apparatus in accordance with the present invention can be advantageously improved.

An example of apparatus in accordance with the present invention is illustrated in the accompanying drawing which shows a diagrammatic elevational view of the apparatus.

The apparatus 1 comprises a base frame 2 and a support frame 3. Arranged on the base frame 2 and between supporting guide uprights 4 of the support frame 3 is a holder 5 for a sand core 6.

The core holder 5 is in the form of a repository which is arranged above the base frame 2 and has a non-slip covering 7 for retaining the sand core 6 in the required position.

A device 8, provided for positioning a number of loosely-hanging strands 9, is located above the core holder 5 and is guided vertically on the guide uprights 4. The strands are each formed by a large number of solid elements 10 which are interconnected so as to be movable relatively to one another. Each strand 9 preferably comprises spherical elements 10 which are spaced from each other.

The device 8 is held in the support frame 3 by way of a hydropulser 11. The hydropulser 11 acts as a servo-motor for moving the strands 9 towards and aways from the sand core 6 as indicated by the arrow "A". It also acts as an oscillation generator which imparts vertical oscillations to the device 8, as indicated by the arrow "B".

The strands 9 which hang loosely from the device 8 and around the sand core 6 are thereby caused to undergo corresponding oscillations.

In this way they are thus pulled past the sand core 6 and as this happens they tear off prominent burrs on the core.

The hydropulser 11 can be set to provide oscillations of differing frequencies and/or amplitudes. These can be altered by a handoperable adjuster or automatically during a deburring operation. This is particularly advantageous for a damage-free inward rounding of the areas at which a core burr is broken off.

For the purpose of reducing, as much as possible, the operating costs of an apparatus 1 integrated in a sand-core production cycle, the hydropulser 11 can be programme-controlled, and it is connected to a power supply (not shown) by way of a time-delay switch (also not shown) arranged in the core holder 5.

The construction of the device 8 may include a perforated plate 12 and a cover plate 13, each strand being held between the two plates 12 and 13 by means of at least one element 10 extending through the perforated plate 12.

The core holder 5 can be so designed that rotation or swivelling of the sand core about an axis is achieved for effecting "all-over deburring".

Claims (10)

Claims

1. Apparatus for deburring sand cores comprising a holder for a sand core and a device which is vertically movable above the core holder and from which loosely hang a number of strands, each comprising a large number of solid elements which are connected to each other in such a manner that they are movable relatively to one another, the device being connected to a verticaloscillation generator in such a manner that a burr can be removed from a sand core held in the core holder by the strands which oscillate with the vertically-oscillating device.

2. Apparatus according to claim 1, in which each strand comprises spherical elements which are spaced from each other.

3. Apparatus according to claim 1 or claim 2, in which oscillations of the vertical-oscillation generator of different frequencies and/or amplitudes can be selected, it being possible to alter the frequency and/or amplitude during deburring.

4. Apparatus according to any preceding claim, in which the level of the device above the core holder can be adjusted by a servo-motor, it being possible for the servo-motor and the verticaloscillation generator to form one unit such as a hydropulser.

5. Apparatus according to claim 4, in which the unit comprising the servo-motor and the verticaloscillation generator is programme-controlled for specific sand cores, the unit being switched on via a time-delay switch arranged in the core holder.

6. Apparatus according to any preceding claim, in which the vertically-moveable device comprises a perforated plate and a cover plate, each strand being held between the two plates by way of at least one of its solid elements.

7. Apparatus according to claim 1, in which the core holder is a repository having a non-slip covering.

8. Apparatus according to claim 1, in which the core holder is designed to rotate or swivel the sand core.

9. Apparatus for deburring sand cores, substantially as described herein with reference to the accompanying drawing.

10. A method of deburring sand cores, using apparatus according to any preceding claim.