GB2073633A

GB2073633A - A casting with ducts which are formed by cast-in tubes

Info

Publication number: GB2073633A
Application number: GB8107860A
Authority: GB
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 1980-04-10
Filing date: 1981-03-12
Publication date: 1981-10-21
Also published as: DE3013745A1; DE3013745C2; JPS57112966A; IT1137211B; FR2480157A1; IT8120896A0

Abstract

Prior to casting a tube 2 is inserted into the mould cavity 41 and mounted therein by means of two retaining pins 5 and 5% which engage within the tube ends 21, 21% and which are received in suitable bores in the mould. The disposition of the tube 2 within the mould is such that the tube end faces 22, 22% are at a distance 34 from the adjacent end faces of the mould cavity 41, that is after casting-in the tube end faces 22, 22% are spaced by the distance 34 from the adjacent unmachined end face 31 of the casting 3/3%. The distance 33 indicates the machining allowance incorporated in the casting mould which is smaller than the distance 34. The spacing 34 enables the casting to be machined without interference from the tube ends. <IMAGE>

Description

SPECIFICATION A casting with ducts which are formed by castin tubes This invention relates to a casting, having ducts which are formed by cast-in tubes, and to a method and a casting mould for producing such casting.

Castings with ducts which can be straight or curved and are produced by cast-in tubes inserted into a casting mould are generally known. Such tubes are usually compressed at their ends and are cast-in projecting, so that the tube ends must be cut off before any further machining or use of the casting. It is particularly difficult to remove the projecting tube ends if they extend, for example, in bores. However, during the machining of contours to which cast-in tubes extend, considerable difficulties are encountered as a result of the differences in material as between the tube and the material surrounding the tube, and also due to the possibly thin wall of tubes. Machining must therefore be adapted to these conditions and over a relatively large machining area, although the end of the tube may be very small.

Moreover, very often with thin-watiled tubes of soft material the tubes become deformed due to the machining, so that they become detached from the surrounding material, the result being untidy, leaky surfaces.

The present invention aims at obviating the foregoing disadvantages and to this end, consists in a casting with ducts which are forrhed by castin tubes, wherein the tube ends are spaced from an adjacent rough or machined end face of the casting.

The invention also consists in a method of producing a casting with ducts which are formed by cast-in tubes, wherein before casting, the tubes are so mounted in a mould by means of retaining pins, which engage in the tubes at their ends, that such ends of the tubes are at a distance from the casting mould contour which is greater than any machining allowance incorporated in the casting mould, the retaining pins being withdrawn from the cast-in tubes before or after removal of the casting from the mould.

The present invention further consists in a casting mould for producing a casting with ducts which are formed by cast-in tubes, wherein retaining pins are mounted in the casting mould and extend into the mould cavity, said pins engaging within the tube ends and positioning the tubes such that the tube ends are spaced at a distance from- the contour of the mould cavity which distance is greater than any machining allowance incorporated in the dimensions of the casting mould.

If the tube to be cast-in is of such dimensions that its ends are at a distance from a casting contour which is rough (i.e. unmachined) or one which must be machined, that is the tube is thus mounted and also cast-in in a casting mould, the disadvantages described do not occur, since there is no necessity-to remove the usually projecting tube ends. Similarly, the machining of, for example, a surface or bore can be effected without regard to the size or material of the inserted tube.

Nor can, for example, a very thin tube any longer become deformed.

If the tubes are retained in the mould cavity by at least one longitudinally movable retaining pin (claim 6), the tube can be very conveniently and simply inserted into the casting mould, which can also be very simply adapted to any subsequent machining conditions (distance).

If the retaining pin is also spring-loaded (claim 7), larger tolerances of tube length can be accepted without disadvantages, the result being cheaper manufacture.

The optional features of both claims 8 and 9 provide a very simple solution of the sealing problems during the casting-in of the tube. A slight conicity of the locking pin (claim 8) can even out any diameter tolerances -in the tube and also facilitates the removal.of the retaining pin after the casting operation. The tubes can also be cut to length very roughly, since their ends are cast in and are not required as reference edges for the retaining-pin. The optional feature of claim 9 makes it very easy to position the tube in the longitudinal direction; since the retaining pin bears via a shoulder against the end of the tube. The shoulder, which acts as an abutment, can have a diameter smaller than, equal to, but also substantially larger than the external diameter of the inserted tube, thus enabling all problems of connection to be solved in a very simple manner.

If a tube must be secured not only in the axial direction but against twisting in order to be cast in, since the tube is bent, a retaining pin and the corresponding tube end may be profiled in a very simple manner, thus determining a required position in the peripheral direction also.

In order that the invention may be more readily understood, reference is made to the accompanying drawings which illustrate diagrammatically and by way cf example embodiments thereof, and in which Fig. 1 is a cross-section through a casting mould with a casting and a cast-in tube and tube retaining pins for the tube, Fig. 2 is a fragmentary view of Fig. 1, showing a retaining pin with a conical portion, Fig. 3 is a fragmentary view of Fig. 1, showing a retaining pin with a cylindrical portion and abutment, Fig. 4 is a similar view to that of Fig. 1, showing a retaining pin profiled with a bent tube, and Fig. 5 is a cross-section on the line V-V of Fig. 4.

Fig. 1 shows a casting 3 having a cast-in duct 1 which is formed by a tube 2 inserted into the two halves 4,4' of a casting mould. In this embodiment, before and while being cast in, the inserted tube 2 is retained in position by retaining pins 5,5'. Ends 22,22' of the tube 2 are at a distance 34 from the casting mould inner contour 41 which is substantially equal to the outer contour of the raw casting, and the machining allowance 33 on the casting is smaller than the distance 34 between the tube 2 and the raw casting outer contour, so that machining can be carried out without the tool reaching the tube.

Conveniently the casting mould 4,4' is divided at the place 7 of the inserted tube 2, so that the retaining pins 5,5' are mounted in both halves 4,4' of the casting mould.

Fig. 2 shows a retaining pin 50 which positions the inserted tube 2 and which seals the tube 2 by a cone 51, the retaining pin 50 being forced by a spring, for example a helical spring 6, in the direction of the inserted tube 2. In such construction of the retaining pin 50, it is convenient to provide the bearing for the pin only in one half 40 of the casting mould and to locate the mould juncture 7 elsewhere. With sand moulding, for example, a sleeve can of course also be inserted in which a spring loaded retaining pin is mounted.

In Fig. 3 the retaining pin 500 is shouldered between diameters 52 and 53 and sealing of the tube 2 is effected at the end surface 22 of the tube 2. The larger diameter 53-of the retaining pin 500 can be only slightly larger than the internal diameter 23 of the tube 2, which is therefore also partially cast-in at the end surface 22. In the embodiment illustrated in Fig. 3 the larger outer diameter 53 of the retaining pin 500 is equal to the outer diameter of the inserted tube 2.

Figs. 4 and 5 illustrate an arrangement in which a bent, inserted tube 2 can in a very simple manner be so compressed at one tube end 21", for example ovally 25 (Fig. 5), that security is afforded against rotation, so long as the retaining pin 500 is correspondingly shaped at 54 and also has a means for providing security against rotation, for example, in the form of a flattened portion 55.

Claims

1. A casting with ducts which are formed by cast-in tubes, wherein the tube ends are spaced from an adjacent rough or machined end face of the casting.

2. A casting, substantially as herein described with reference to and as shown in the acconipanying drawings.

3. A method of producing a casting with ducts which are formed by cast-in tubes, wherein before casting, the tubes are so mounted in a mould by means of retaining pins, which engage in the tubes at their ends, that such ends of the tubes are at a distance from the casting mould contour which is greater than any machining allowance incorporated in the casting mould, the retaining pins being withdrawn frqm the cast-in tubes before or after removal of the casting from the mould.

4. A method of producing a casting, substantially as heiein described.

5. A casting mould for producing a casting with ducts which are formed by cast-in tubes, wherein retaining pins are mounted in the casting mould and extend into the mould cavity, said pins engaging within the tube ends and positioning the tubes such that the tube ends are spaced at a distance from the contour of the mould cavity which distance is greater than any machining allowance incorporated in the dimensions of the casting mould.

6. A casting mould as claimed in claim 5, wherein the tubes are retained in the mould by longitudinally movable retaining pins.

7. A casting mould as claimed in claim 6, wherein the retaining pins are spring-loaded.

8. A casting mould as claimed in claim 6 or 7, wherein the retaining pins are constructed conically in the zone of the tube end and of the contour of the mould cavity.

9. A casting mould as claimed in claim 6 or 7, wherein the diameter of the retaining pins is smaller in the zone of the tube end and larger in the zone of the contour of the mould cavity than the internal diameter of the tube.

10. A casting mould as claimed in claims 5 to 7, wherein at least at one tube end bent tubes have contours differing from the circular and cooperating with a corresponding contour of the retaining pin.

11. A casting mould, substantially as herein described with reference to and as shown in the accompanying drawings.