FOR FILTERS FOR VEHICLES. PARTICULARLY FOR OIL

FILTERS. AND COVER PRODUCED THEREBY

The present invention refers to a process for

manufacturing a single-component cover for filters

for vehicles, particularly for oil filters, and to

the cover produced through this process.

Figs. 1 to 3 show a cover 10 produced according to the prior art, to be used on an oil filter to cover it according to well-known operating techniques and principles.

In particular, the cover 10 is composed of a central part 11 of a circular shape, and centrally open in order to form a threaded opening 12, through which the filter will be screwed to the

block. The cover is then equipped with a thinner

external ring 13, that is used for seaming to the cup 14 containing the filtering cartridge. Such seaming occurs at point 16 shown in Fig. 3.

The cover is then equipped, in a known way,

with a plurality of holes 18 for the passage of

oil.

The cover 10 must have two well-defined operating properties:

1) the thickness of the cover 10 itself must

be adequately high (of the order of 1.7/3 mm) in

the central threaded part 12 thereof, to support

high pressures occurring during its operation; in

particular, the cover 10, during design, must be

resistant to bursts to which it is subjected during

pulsating tests;

2) the thickness of the cover 10 must instead

be adequately thin (of the order of 0.8 mm) in the

external annular part thereof, where the cover 10

must be bent in order to seam it to the filter cup

14, so that the filter itself can be completely

closed.

In order to realize a cover having two

different thicknesses, applying the prior art, two

different components are used, of materials

commonly known as P04 and PI3, where the two

numbers following letter P are determined by the

different carbon compositions therein and by other

properties. The P04 component, about 0.6 m thick,

is normally used to make the external ring 13,

while the P13 component, about 2.5 mm thick, is

normally used to make the central threaded part 12

of the cover 10. The two components, separately

produced with two known pressing processes, are

then welded together, through a third welding

process, at points 20 and 22 in Fig. 2. As appears

from what has been described before, the procedure

to produce covers for oil and other types of

filters has always been cumbersome and costly,

since it employs two different types of material

and several intermediate steps.

Purpose of the present invention is solving

the above-said problems, providing a process for manufacturing a cover for oil filters and other types of filters that meets the above-listed

operating requirements, and at the same time can be manufactured using a single starting component or blank and employing a unique, linear procedure that can be easily realized and has a reduced cost.

This cost reduction is obtained also because

the manufactured product does not need any heat

treatment.

The above and other purposes and advantages of the invention, such as those resulting from the

description below, are obtained through a process

for manufacturing a single-component cover for

filters for vehicles, particularly for oil filters,

as claimed in claim 1.

The present invention also relates to the

cover produced through one of the above-listed

processes: this cover shows the advantages of a

high resistance to pressures and of an easy seaming

and it is simple and inexpensive to manufacture,

since it does not require any heat treatment. The

cover can be used both for fuel filters and for oil filters for vehicles.

The present invention will be better described

by some preferred embodiments thereof, given as a

non limiting example, with reference to the

enclosed drawings, in which:

- Figure 1 is a top view of a cover for an oil filter for vehicles;

- Figure 2 is a side-sectional view of the

cover according to the prior art, carried out along

line II-II in Fig. 1;

- Figure 3 is a side view of an oil filter for vehicles with the cover of Fig. 1 seamed to the filter containing cup;

- Figures 4 to 7 show the successive steps of

a first alternative process for manufacturing

covers for filters according to the present

invention;

Figure 8 shows one of the steps of a variation of the process for manufacturing covers

for filters according to the present invention;

- Figures 9 to 11 show the successive steps of

a second alternative process for manufacturing

covers for filters according to the present

invention; and

- Figures 12 to 22 show the successive steps

of a third alternative process for manufacturing

covers for filters according to the present

invention.

Figures 1 to 3 show a cover 10 for oil filters according to the prior art and have been previously described.

The inventive process for manufacturing a

cover 10 for filters using a single component begins by providing a starting single-component slab 10 of a circular shape (or of any other shape useful to manufacture covers for filters). This

slab 10 is composed of a material whose thickness varies between 1.7 mm and 3 mm, depending on the

filter size; this thickness is the necessary one to stand the high operating pressures.

In order to obtain the two above-said

operating thickness measures, according to a first

alternative process of the invention (shown in

Figures 4 to 7 and 8), firstly a drawing operation

is carried out, by means of a press, to the slab 10

in the part 24 thereof corresponding to the central

hole, as shown in Fig. 4. At this stage, thickness

is not critical.

Then, by means of a press, trimming in 26 of

the central drawn part 24 of the slab 10 is carried

out, as shown in Fig. 5: through this trimming

operation, thickness in 26 is reduced to about 1

mm.

Bending is then carried out in 28, by means of

a press, of the trimmed part on itself and then squashing is performed, always by means of a press, of the bent part in 28 against the internal wall

itself previously obtained through drawing. Purpose

of these two operations, shown in Fig. 6, is increasing thickness in the central part 12 to the required 2.5 mm, and they strengthen the area where threading will be carried out.

It is possible, in practice, to carry out this

bending operation in two ways, one of which is

shown in Figure 6: bending is carried out in such a

way as to generate a bend with upward-oriented

concavity (Fig. 6) or with downward-oriented concavity (not shown) with the result of creating a

reinforcing bead next to the central part 12. This

bending step is always followed by a squashing step

to complete such step.

After having solved the thickness problem in

the central part 12, the edge-bending step of the

external edge 30 of the slab 10 is carried out

reducing the external thickness thereof to 0.8 mm,

through a material-stretching operation: this step is shown in Fig. 7. In this way, thickness

reduction on the external edge 30 is also carried

out and the desired single-component cover for filters is obtained.

The last manufacturing steps for such cover are then carried out in a known way: they are

threading the central part 12 of the slab 10, and seaming the external edge 30 of the slab 10 to the filter-containing cup 14. These operations, being

well known in the art, have not been described.

Thickness reduction of the external edge 30 of the slab 10 can also be realized in an alternative

way, using a variation of the inventive process, variation according to which the bending and

squashing step 4) (Fig. 6) and the bending and stretching step 5) of the external edge 30 (Fig. 7)

are replaced by the redrawing step of the external edge 30 itself, reducing the external thickness

thereof through at least 5 successive pressing

stages.

This last step is shown in Fig. 8 and allows

bringing the initial thickness of the slab 10, that

in this variation is equal to about 2 mm, to the

0.8 mm required for seaming. As shown in Figure 8,

bending of the central trimmed part 26 is no more necessary, since it already has such a thickness as

to satisfy the operating requirements.

According to a second alternative process for

manufacturing filters for vehicles, shown in

Figures 9 to 11, after having provided the starting

single-component slab 10, the process begins by

carrying out a drawing operation, by means of a press, to the slab 10 in the part 24 thereof corresponding to the central hole, as shown in Fig. 9. At this stage, thickness is not critical and is reduced to about 1 mm.

Then, by means of a press, trimming in 26 of the central drawn part 24 of the slab 10 is carried

out, as shown in Fig. 10: after this trimming

operation, thickness in 26 remains reduced to about 1 mm and becomes critical.

Upsetting or heading the slab 10 is then carried out, by means of upsetting wheels, starting

from the external circumferential edge 30 thereof,

as shown in Fig. 11. The upsetting step consists in

moving the material from the external edge 30

towards the central trimmed part 32 through a

plurality of successive passes. Finally, a

thickness decrease is obtained in the external edge

30 of the slab down to approximately 1 mm. and a

thickness increase in the central trimmed part 32

of the slab up to approximately 1.5 mm, making

these two thicknesses suitable to be operatively

used.

According to a variation (not shown) of this second alternative process, the above-said upsetting or heading step is carried out before the drawing and trimming steps, without affecting in any way efficiency and optimum yield of the process itself, and without any modification of the final product being made.

According to another variation (not shown) of this second alternative process, the above-said

upsetting or rolling step is carried out through drawing without moving material towards the central part of the slab 10, which thereby does not

increase its thickness.

The last manufacturing steps for such cover

are similar to the ones described above: they are

threading the central part 32 of the slab 10, and

seaming the external edge 30 of the slab 10 to the

filter-containing cup 14. These operations, being

well known in the art, have not been described.

According to a third alternative process (that

is also the preferred one) for manufacturing filters for vehicles, shown in Figures 12 to 22,

after having provided the starting single-component

slab 10, the process begins by carrying out a

drawing operation (shown in Fig. 12), by means of a

press, of the slab 10 in the central part 34

thereof. This drawing provides the "dome" shape,

improving operating performances of the cover 10.

Then, forming is carried out (Fig. 13) of the internal wall 35 of the seat 36 where a sealing gasket (not shown) will be housed; this internal

wall 35 is placed externally with respect to the central drawn part 34.

The central and inventive part of this third

alternative process is reducing the thickness of

the external edge 30 of the slab 10; this step is further divided into the following steps:

- bending (Fig. 14) the external edge 30 at

such an angle as to allow realizing the following

extruding step and the forming step of the external

wall of said gasket seat 36; this angle is equal to

about 90°, that is, bending occurs so that the

external edge 30 is placed vertically;

- extruding (Fig. 15) an annular part of the

external edge 30 till the thickness thereof is

brought to the final operating value (about 0.8 mm

or even less): this extruding step leaves an

extreme circular crown 38 of the external edge 30

whose thickness is unchanged with respect to the initial one; purpose of this extreme circular crown

38 is avoiding that the material cracks during the

following bending steps;

- bending (Fig. 16) the external edge 30 for a first time in such a way as to form a first angle α with respect to the axis of the cover 10: after several experiments, it has been discovered that, for a better operating result, angle α ranges between 20° and 40°, and preferably between 25° and 35°, most preferably 30°; the first bending is realized in the opposite direction with respect to

the one where bending in the previous step shown in

Fig. 14 had been realized;

- bending (Fig. 17) the external edge 30 for a

second time in such a way as to form a second angle

β, greater than the angle , with respect to the

axis of the cover 10; after several experiments, it

has been discovered that, for a better operating result, angle β ranges between 40° and 60°, and

preferably between 45° and 55°, most preferably

50°;

- bending (Fig. 18) the external edge 30 for a

third time in such a way as to bring it back to its

initial position, that is substantially horizontal

and at a right angle with respect to the axis of the cover 10; and

- trimming (Fig. 19) the external edge 30,

thereby removing the extreme circular crown 38.

After having reduced the thickness to a value

of about 0.8 ram or less, that allows an easy seaming thereof, the known steps are carried out of

final forming (Fig. 20) the external edge 30 of the

slab 10; punching (Fig. 21) the slab 10 in order to form the central hole 42; and turning the edge

(Fig. 22) in the formed central hole 42 of the slab

10.

The last manufacturing steps for such cover are similar to the ones described above: they are threading the central hole 42 of the slab 10, and seaming the external edge 30 of the slab 10 to the

filter-containing cup 14. These operations, being

well known in the art, have not been described.

According to a variation (not shown) of this

third alternative process, the extruding step can

be carried out on an external circular crown whose

height is greater than 17 mm. , that is the minimum

one under which cracks can occur (without the

presence of said extreme circular crown) when performing afterwards the first bending step.

According to another variation of this third

alternative process, the drawing, trimming and

threading steps can be carried out before the step of reducing the thickness of the external edge 30: this because these steps are somewhat independent from the other ones and can be realized at any time during the process.

Finally, as further improvement of one of the steps of the present inventive process, the

threading steps in all its alternatives can be carried out by removing chips, or by rolling, or in

other equivalent ways.

The invention is further related to the single-component cover 10 manufactured employing

one of the above-described alternative processes.

The single-component cover 10 for filters for

vehicles thus manufactured and shown in the Figures

is provided with inventive features with respect to

similar covers designed or realized previously: in

fact, none of the prior art single-component covers

managed to stand the high operating pressures

without breakages, or the processes to produce

these prior art overs have always been too complex

and too costly for mass production.