GB2038675A - Process and device for separating excess material - Google Patents

Abstract

The runner bar 2 and a centring element 3 are used to locate a casting tree in a cutting machine to remove castings preferably by plasma cutting. <IMAGE>

Description

SPECIFICATION Process and device for separating excess material The invention relates to a process and a device for the mechanical separation of feeding and cutting elements of complicated castings and complex casting arrangements, more especially in the case of armature casting, by means of thermal separating processes, more especially plasma cutting.

Various processes are known for separating the excess material from the casting and extracting the individual parts from complex casting arrangements, which range from the mechanical separation by means of sawing or abrasive cutting-off over the use of thermal separating processes to the formation of breaking zones for breaking off the feeding and cutting elements. Thus, a device for separating funnels on castings has already been shown (DL AP 123 274), composed of a rotating table for chucking the castings and of one or more flame cutters as severing tools which perform the severing cut, manually or automatically controlled.

Furthermore, a process for the manufacture of metallic castings is known (German Offenlegungsschrift 2 363 940), in which easily and cleanly severable feeders are obtained by means of a close communication between the main member of the feeder and the hollow space of the mould.

The use of known thermal severing processes, such as flame-cutting with unalloyed and lowalloyed cast steel, the electrode arc-cutting with high-alloy cast steel, the powder flame-cutting with high-alloy cast steel and non-ferrous metals, and also plasma fusion cutting, takes place manually for the most part. Mechanized thermal severing processes are known onlyforthe machining of castings with a simple geometrical shape.

Generally, the mechanization of the process of severing feeding and cutting elements from the casting is constituted in such a way that before the actual severing of the excess material, the casting is separated from the casting arrangement at some point within the cutting system and then the severing operation between the casting and the feeding or cutting element is carried out at a definite point. In manual thermal severing processes, on the other hand, the individual castings are immediately separated from the feeding and cutting elements within the casting arrangement, without any preliminary separation. An inadequate quality of cut is produced by the manual severing processes, caused by the fact that no precisely defined cut can be carried out when the torch is guided manually.From this arises the necessity for subsequent machining of the severing areas, in order to shape their residual height in such a way that subsequent machining on mechanical and automated machines is made possible.

In the mechanized form of thermal severing processes, the necessary quality of the cutting area is obtained without mechanical after-machining. The disadvantage of known processes is the necessity for preliminary separation, which means additional work and also extra expense in manufacture. This necessity is a result of the positioning of the castings inside the casting arrangement, which is carried out in accordance with conditions of casting technology.

Demands of cleaning and severing technology are not sufficiently taken into account here. The centring elements for chucking in order to carry out mechanical machining are on the castings and cannot be used for positioning in the severing operation, as this is constantly linked with overdefinition (redundancy).

The mechanization of the thermal separation of the excess material from the casting necessitates the use of a corresponding device for positioning the castings in order to guarantee a definite course of the cut.

A process and a device for machining preferably cast and unevenly shaped components is already known (DL WP 75216), in which the components are manufactured together with a frame which connects them, and with the aid of which the parts are chucked on the machine.

Furthermore, a device for supporting workpieces for the purpose of mechanical machining has already been shown (DL AP 83 506), which is composed of fastening points arranged in a regular pattern on a pallet. Aframe for larger castings, more especially for armature casting would signify considerable additional use of material. The supporting device described in Patent DL AP 83 506 is not suitable for use with thermal separation.

The present invention preferably provides a process and a device for the mechanical separation of the excess material from castings and for the extraction of castings from complex casting arrangements by means of thermal separating processes, more especially plasma (fusion) cutting, which on the severing areas ensure castings which need little subsequent machining or are free from it, and are true to dimensions. For the extraction of castings from complex casting arrangements, this is intended to be made possible without prior separation.

The problem underlying the invention is that of the development of a process and a device which make possible the mechanized thermal separation, more especially by means of plasma cutting, of the excess material from castings and complex casting arrangements, in which severing areas which need little subsequent machining or are free from it and are true to dimensions are obtained without prior separation of the castings and without additional mechanical machining.

According to the present invention the feeding and cutting system for the positioning and centring of the casting or the complex casting arrangement is provided with special centring elements and/or is itself constructed as a centring element, and a unit centring device is used whose two receiving elements each have the opposite geometrical shape to the corresponding centring elements of the casting arrangement, wherein one of the receiving elements is constructed as an opening and the second is constructed in accordance with the shape of crosssection of the feeding and cutting system. This device isfloatingly mounted on a base plate and has to be centred before the severing operation.The severing operation itself always proceeds in such a way that the cut between the casting and centring point or the between the casting and the gate or the feeding element connected with it is carried out as the last cut.

The positioning and centring of the castings or casting arrangements takes place only by means of the positive connection of their centring elements to the corresponding receiving elements of the device and their dead weight. Additional tension forces from outside are not used.

Exemplified embodiments Figure 1: Top plan view of a feeding and cutting system with a circular cross-section designed in accordance with the invention Figure 2: Side view of a feeding and cutting system with a circular cross-section designed in accordance with the invention Figure 3: Top plan view of a feeding and cutting system with a rectangular cross-section designed in accordance with the invention Figure 4: Side view of a feeding and cutting system with a rectangular cross-section designed in accordance with the invention Figure 5: Top plan view of a feeding and cutting system with a triangular cross-section designed in accordance with the invention Figure 6: Top plan view of a feeding and cutting system according to the invention, in which the intake fulfils the function of feeder at the same time Figure 7:Side view of a feeding and cutting system according to the invention, in which the intake fulfils the function of feeder at the same time Figure 8: Top plan view of a feeding and cutting system designed according to the invention, in which the intake itself cannot be used as a centring element Figure 9: Side view of a feeding and cutting system designed according to the invention, in which the intake itself cannot be used as a centring element Figure 10: Top plan view of a feeding and cutting system designed in accordance with the invention, in which a core mark denotes the centring point Figure ii: Side view of a feeding and cutting system designed in accordance with the invention in which a core mark denotes the centring point Figure 12:Sectional representation of a centring device according to the invention The exemplified embodiments will be explained in greater detail hereafter.

In Figures 1 and 2 is illustrated a construction of the centring system according to the invention on a --erdin-3 nd cutting system with a circular crosssection. The gate 1 is of no significance here for the centring. The centring pin 3 and the intake 2 are used as centrir elements, where the centring pin 3 engages in a corresponding opening 11 on the device (F:gure 12), whilst the intake 2 with a circular cross-section is mounted on a prism 10. The centring pin 3 in this case lies outside the actual feeding and cutting system. Figures 3 and 4 show a construction according to the invention, on a feeding and cutting system with a rectangular cross-section. The centring pin in this case lies inside the feeding and cutting system and again engages in the corresponding opening 11 of the device (Figure 12).The mounting of the intake 2 in this case is carried out in a prism which corresponds to its shape, instead of the prism 10.

The illustration in Figures, similar to the case shown in Figures 3 and 4, a centring in accordance with the invention, in which the intake has a triangular cross-section whose mounting is carried out on a roller prism instead of the prism 10 of the device (Figure 12).

In Figures 6 and 7 is represented a construction according to the invention, of a centring on a feeding and cutting system, in which (centring) the intake 2 at the same time fulfils the function of a feeder. The centring pin 3 is located underneath the intake 2. The feeding and cutting system itself cannot, in this case, be used as a second centring element, as with the dual function of intake and feeder, a corresponding geometry cannot be obtained in casting technology.

For this reason, there is located underneath the intake 2 at a corresponding spacing to the centring pin 3, an additional centring element 4 whose cross-section can be made circular, rectangular or triangular, depending upon the shape of crosssection of the intake 2.

Figures 8 and 9 show a construction of the centring according to the invention, in which, similar to the type shown in Figures 6 and 7, the intake itself cannot be used as a centring element. The additional centring element 4 is not located underneath the intake 2, however, but in this case is located underneath the feeder 5, where its shape of crosssection is constructed in accordance with that of the intake 2.

A problem which frequently occurs in practice is illustrated in Figures 10 and 11. Sometimes, parts of the model cover the centring point. The illustration in Figures 10 and 11 shows the construction of the centring according to the invention. To this end, the core mark 7 is so re-shaped that it is partly shortened in the bottom flask of the mould and is locked in the core box, but remains formed on the model. It is cut from the intake 2, so that the hollow space 8 fills with metal and can be used as a centring point.

Figure 12 shows the construction according to the invention of the device for centring casting arrangements during mechanized separation of the excess material from the castings. The device is composed of the base plate 9, which is mounted by means of the mountings 12 on the plate 13 which revolves on a roller belt. On the base plate 9 are located parallel to each other, two receiving elements with an opening 11 and two receiving elements in the form of a prism 10. This parallel arrangement makes the simultaneous machining of two casting arrangements possible.

The prisms 10 can be replaced by differently shaped receiving elements in s specific instance of use, depending upon the shape of cross-section of the intake 2 or the additional centring element 4.

In all the exemplified embodiments shown there takes place the following general processtechnological sequence of separating the excess material or extracting the castings from a complex casting arrangement.

Two castings at a time are positioned with the aid of their centring pin 3 and their intake 2 or of an additional centring element 4 against the receiving elements 10 and 11 on the device, the revolving plate 13 is brought into the working area of the respective flame cutting machine by means of conveying rollers, the device is centred and the separation of the entire feeding and cutting system from the castings then takes place in a fully mechanized way, as the identical position of the complex casting arrangements is always guaranteed. The separating installation must be programmed in such a way here, that between the casting and centring point or the feeding and cutting element connected to it is carried out as the last cut.

Claims (10)

1. Process and device for separating excess material, more especially for the mechanized separation of feeding and cutting elements from complicated castings and complex casting arrangements by means of thermal severing processes, preferably plasma (fusion) cutting, characterized in that the feeding and cutting system for the positioning and centring of the casting (6) or the complex casting arrangement is provided with special centring elements (3 and 4) and or is itself constructed as a centring element, where the centring elements (3,4) can be situated both inside and outside the cutting system.

2. Process and device for separating excess material as claimed in Claim 1, characterized in that a centring pin (3) in which the ratio of diameter to length is equal to 1: R 1 and the intake (2) in the cutting system are provided as centring elements.

3. Process and device for separating excess material as claimed in Claim 2, characterized in that an additional centring element (4) underneath the intake (2) or underneath the feeder (5) is provided as a second centring element instead of the intake (2).

4. Process and device for separating excess material as claimed in Claim 2, characterized in that a hollow space (8) which is moulded out of core marks (7) which are en the model and is filled with metal by the cutting system is used to produce the second centring element.

5. Process and device for separating excess material as claimed in Claims 1,2,3 and 4, characterized in that the cross-section of the cutting system is circular, rectangular, triangular or trapezoidal.

6. Process and device for separating excess material as claimed in Claims 1,2,3,4 and 5, characterized in that the device is composed of a base plate (9), which is floatingly mounted by means of the mo Inting (12) on a plate (13) which revolves on a roller belt, on which (plate 9) there are located parallel to each other, two receiving elements with an opening (11) and two receiving elements (10), which are shaped in accordance with the shape of cross-section of the centring element (4) or of the intake (2).

7. Process and device for separating excess material as claimed in Claim 6, characterized in that the receiving elements (10 and 11) are so arranged on the base plate (9) that two complex casting arrangements can be simultaneously centred and synchronously machined, where the centring of the castings or casting arrangements takes place only by means of the positive connection of the centring elements (3 and 4) to the corresponding receiving elements (10 and 11) of the device and with the aid of their dead weight, so that additional tension forces from outside are unnecessary.

8. Process and device for separating excess material as claimed in Claims 1 to 7, characterized in that the separating operation between the casting (6) or complex casting arrangement and the feeding and cutting system proceeds in such a way that between the casting and centring point or the feeding and cutting element connected to it is carried out as the last cut.

9. A process for removing the excess material from workpieces as claimed in claim 1, substantially as hereinbefore described.

10. A device for removing excess material from workpieces substantially as described with reference to and as illustrated by the accompanying drawings.