EP0724921A1 - Tubular housing, in particular for a pump - Google Patents

Abstract

The housing is in the form of a cylindrical tube which has stepped bores at both ends in which bearing covers, e.g. a drive motor can be mounted. The housing is made by deep drawing. The stepped bores at either end are formed with stepped mandrel (13) which is forced into the ends of the tube. The flanges (9) which are formed by the mandrel are folded down against the outside diameter of the part of the mandrel which has the layer diameter.

Description

The invention relates to a tubular housing for pumps, motors and the like., In particular fuel pumps, on the inner wall of which, for tight mounting, for example a bearing plate of a pump motor, a step enlarging the inside diameter of the housing while maintaining the outside diameter is formed. The invention further relates to a method for producing such a tubular housing, in particular for a fuel pump.

Fuel pumps, but also other engines, are often housed in one-piece tubular housings, which are cylinders open on both sides, so that the pump parts to be accommodated in the housing, such as a pump cylinder, a valve block, spring elements and a motor, as well as electrical connections, liquid lines and mechanical connections can be easily inserted and fixed. The known tubular housings have a gradation on both inner sides of their inner wall for tight mounting, for example a bearing plate of a pump cylinder. Pump housings of this type are made from welded, cut-to-length pipe, a step being formed on both sides by subsequent machining and the desired surface qualities and dimensions being produced. This involves a great deal of production effort, which has a considerable adverse effect on the economy and marketability of such pump housings. Technically, it is disadvantageous that the welded design of the housing does not infrequently lead to leaks, which increases the reject rate. The accuracies as well as the shape and position tolerances that can be achieved by the subsequent machining are in need of improvement, which is evident, for example, from the fact that the desired tightness is found The required edge radius of the step can only be produced by turning if new turning tools are used. The double function of the stages, namely to ensure that the pump parts attached to them are secure and leak-proof, can only be ensured through extensive processing and testing.

In summary, it can be stated that the known housings and the processes for their production are technically and economically in need of improvement because of the disadvantages that result from the use of welded pipe and subsequent machining, for which purpose a large number of successive machining steps have to be carried out and high mechanical expenditure is required are.

In view of this prior art, the invention is based on the object , while avoiding the disadvantage mentioned, of specifying an improved pump housing which can be produced in a simple manner without machining.

The object is achieved in that the housing is a deep-drawn part produced without cutting by deep drawing as a forming technique from a round blank, the step being formed by ironing over an internal mandrel corresponding to the shape and dimension of the step. This ensures that, with the same outer diameter, an inner step of the greatest accuracy and surface quality can be produced in an extremely simple manner without machining and, for example, there are no problems, the inner radius of R <0.2 mm desired in a preferred embodiment and an edge chamfer at an angle of approximately Set 30 ° without additional processing step. The pump housing present as a deep-drawn part according to the invention has a great economic advantage, since the part costs are only a third compared to the prior art, the technical quality being significantly improved since, due to the lack of a welded seam, no leaks must be expected and the manufacturing accuracy is increased.

According to a preferred embodiment, the deep-drawn part is a cylinder which is open on both sides and has the gradation produced without cutting on each open side at a predetermined distance. With the outside diameter remaining the same, there is a reduced wall thickness in the gradation area with an enlarged inside diameter compared to the central part of the housing. Compared to the prior art, it is advantageously achieved that the shape and position tolerances are smaller, the roughness depths that can be achieved are smaller and, finally, a material solidification is achieved by the production, which makes the pump housing less sensitive to damage during handling, in particular when galvanic aftertreatment or during transport.

In terms of method, the tubular pump housing described is produced according to the invention in that, in a departure from the previous method, a cup-shaped hollow body is produced in a first process step from a metal blank by deep drawing or deep-pressing in several steps, that this hollow body is exposed to its free edge in a second process step is expanded and the bottom of the pot is removed to provide a hollow cylinder that is open on both sides, that an internal mandrel is then inserted into the extension, the shape, dimensions and surface of which is adapted to the step to be machined without cutting, and that the step on the inner wall of the hollow cylinder is produced by ironing in several steps over the inner mandrel and finally the inner mandrel is removed and the housing is cut to length if necessary. The second open side of the hollow cylinder is preferably also expanded before being cut to length, and a further gradation is produced on the inner wall of the hollow cylinder by ironing in several steps over the inner mandrel.

A sufficient amount of material for the subsequent ironing is advantageously provided in the extension area in order to be able to produce the gradation in the desired length and wall thickness without further processing, with a degree of deformation of about 50% being set. The extension is preferably V-shaped, but it should be noted that rectangular expansion is also possible in principle.

Fig. 1

ein Kraftstoffpumpengehäuse im Schnitt,

Fig. 2

einen vergrößerten Ausschnitt "Y" des Kraftstoffpumpen-Gehäuses der Fig. 1,

Fig. 3

einen vergrößerten Ausschnitt "X" des Kraftstoffpumpen-Gehäuses der Fig. 1,

Fig. 4

die stufenweise Herstellung eines Kraftstoffpumpen-Gehäuses gemäß Fig. 1 in Einzelansichten Fig. 4/1 bis Fig. 4/8, schematisch.

Further details, features and advantages of the subject matter of the invention result from the following description of the accompanying drawing, in which a pump housing and various process stages for its manufacture are shown schematically. The drawing shows:

Fig. 1

a fuel pump housing in section,

Fig. 2

2 shows an enlarged section "Y" of the fuel pump housing of FIG. 1,

Fig. 3

2 shows an enlarged section “X” of the fuel pump housing of FIG. 1,

Fig. 4

the gradual manufacture of a fuel pump housing according to FIG. 1 in individual views Fig. 4/1 to Fig. 4/8, schematically.

The tubular housing 1 of a fuel pump shown in FIGS. 1 to 3 of the drawing represents a hollow cylinder of circular cross-section which is open on both sides and has an identical outer diameter D _A throughout. The housing 1 consists of a central part 2, which merges on both sides into a gradation area 3 or 4, which is drawn in an enlarged representation in FIGS. 3 and 4 of the drawing. The inner diameter D _{I of} the central area increases in the gradation areas 3 and 4 to an average value D _Z lying between D _A and D _I , the wall thickness in the gradation areas 3 and 4 correspondingly being reduced to approximately half the wall thickness of the central part 2 .

Figures 2 and 3 with the details Y and X in an enlarged view show the gradation areas 3 and 4 and in particular illustrate that the steps 5 and 6 provided adjacent to the open sides of the housing 1 are worked out at right angles from the inner wall of the housing 1, wherein an inner radius R 0.2max must be observed in order to keep the bearing plates for fuel pump parts in contact and pressed against stages 5, 6 in the finished state in a liquid-tight manner without additional sealants.

It can also be seen that the transition edge to the central part 2 is chamfered at an angle of 30 °.

The housing 1 is produced in accordance with FIG. 4 of the drawing in various process steps. This is based on a metal blank 7, that is to say a flat circular sheet metal part, from which a pot-shaped hollow body 8 is produced as shown in FIG. 4/1 by using deep drawing as the forming technique. The deep-drawing is carried out in a manner known per se in such a way that the blank 7 is pulled by means of a preceding stamp and a drawing ring and a vessel is formed in this way, the blank diameter - as shown in the drawing - being different from the starting diameter during the deep-drawing steadily reduced and reached the punch diameter towards the end of the drawing process. The pulling is carried out in several steps, this process being illustrated by Fig. 4/2.

4/3 of the drawing, the free edge of the pot-shaped hollow body 8 is then widened outwards (antulpen), a V-shape for the antulping / widening 9 being selected in the preferred exemplary embodiment according to the drawing. Then the bottom of the pot 10 is removed by punching to form a sleeve 11 open on both sides according to FIG. 4/4 of the drawing. It can be assumed that the material thickness does not change on average by this deep-drawing process in several stages up to this process step and that the surface of the starting blank 7 and the sleeve 11 are therefore approximately the same size. Due to the deformation, the material has already solidified.

The further processing now takes place in the forming process of deep-drawing in a further step, the sleeve 11, which is pulled forward in the stop, being used as the starting shape instead of the flat cut. The aim here is to form stages 5 and 6 in a simple manner, the drawing part thereby being brought to its final length at the same time. The process of deep drawing in continuous blow is known as such and is also referred to as ironing, which is preferably carried out in several steps becomes. An inner mandrel 12 is inserted into the antulpung 9 according to FIG. 4/5 of the drawing from below or the sleeve 11 is placed over such an inner mandrel. This is adapted in shape, dimensioning and surface to the level 5 or 6 to be produced without cutting and thus has a pin 13 projecting into the sleeve 11 and a stamp part 14. The pin 13 has an outer diameter which is matched to the inner diameter D _{I of} the sleeve 11, while the stamp part 14 has a diameter which corresponds to the inner diameter D _Z in the gradation area of the finished housing 1. The shape, dimensions and surface of the inner mandrel 12 are matched to the gradation areas 3 and 4 to be produced in the subsequent drawing process. With a reduction, not shown, the further forming is now carried out in several stages. Fig. 4/6 shows the result. The step 5 now formed on one side of the sleeve 11 can be seen.

In order to also form the second gradation 6 on the opposite side of the sleeve 11, a repetition of the above-described process steps is carried out in a V-shape and the ironing process according to FIGS. 4/7 is repeated to produce the finished housing according to FIG. 4 / 8, which has the desired gradation areas 3 and 4 according to FIG. 1 of the drawing on its two open sides.

It is self-evident and therefore not described in detail that the diameter reductions which can be achieved in one step in the case of step-by-step forming depend on the material, the lubrication, the tool design and whether or not the material was annealed after the stop. Although a circular blank made of metal / steel was assumed in the above description, the housing can also be made from plastic by mechanical deep drawing.

Reference list

1

casing

2nd

Central part

3rd

Gradation range

4th

Gradation range

5

step

6

step

7

Round blank

8th

pot-shaped hollow body

9

Enlargement or antulpung

10th

Pot bottom

11

Sleeve

12th

Internal mandrel

13

Cones

14

Stamp part

15

Enlargement / Antulpung

D _I

Inside diameter

D _A

outer diameter

D _Z

Gradation range

R

Inner radius

Claims (8)

Tubular housing for pumps, motors and the like, in particular fuel pumps, on the inner wall of which for the tight mounting, for example of a bearing plate of a pump motor, a step (5 or 6) which increases the inside diameter (D _I ) of the housing (1) while the outside diameter (D _A ) remains the same. is trained, characterized, that the housing (1) is a deep-drawn part produced by deep drawing as a forming technique from a round blank (7), the step (5 or 6) being formed by ironing over an internal mandrel (12) corresponding to the shape and dimension of the step. Housing according to Claim 1, characterized in that the deep-drawn part is a cylinder (sleeve 11) which is open on both sides and has the step (5 and 6) formed by ironing at a predetermined distance on each open side. Housing according to claims 1 and 2, characterized in that the step or steps (5 or 6) have an inner radius of R <0.2 mm and have a bevelled edge at an angle of approximately 30 °. Housing according to one of claims 1 to 3, characterized by a constant outer diameter (D _A ) and an inner diameter (D _I ) which is expanded in the gradation area (3 and 4) to an enlarged inner diameter (D _Z ) while reducing the wall thickness. Method for producing a tubular housing, in particular a fuel pump housing, according to one of claims 1 to 4, characterized in that in a first process step, a cup-shaped hollow body (8) is produced from a metal blank (7) by deep drawing or deep pressing in several steps. that the hollow body (8) is expanded in a second process step at its free edge to the outside (extension 9) and the pot bottom (10) is removed to provide a hollow cylinder (sleeve 11) open on both sides that in the extension (9) an inner mandrel (12) is used, which is adapted in shape, dimension and surface to the non-cutting step (5), and that the step (5) on the inner wall of the hollow cylinder (11) by ironing in several steps is produced over the inner mandrel (12) and finally the inner mandrel (12) is removed and the housing (1) is cut to length if necessary. Method according to claim 5, characterized in that the second open side of the hollow cylinder (sleeve 11) is expanded (extension 15) and a second step (6) is formed on the inner wall of the hollow cylinder by ironing in several steps over the inner mandrel (12) becomes. Method according to claims 5 and 6, characterized in that in the area of the extensions (9 or 15) a sufficient amount of material is provided for the subsequent ironing to produce the step (5 or 6) in the desired length and wall thickness without further processing, a degree of deformation of about 50% is set. Method according to one of claims 5 to 7, characterized in that the extension (9 or 15) is V-shaped.

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