Note: Descriptions are shown in the official language in which they were submitted.
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P83 o68/GMD TOOL FOR AND METHOD OF
MAKING HOLLOW ARTICLES
This invention relates to the manufacture of hollow
articles. The invention has been developed for the manufac-
ture of the outer member of a constant velocity universal
joint of the cross-groove type. In such a joint, ~here is
an inner member and an outer member, the outer member having
an internal cylindrical surface and the inner member an
external cylindrical surface which surfaces are grooved and
there are two sets of, preferably, helical grooves in each
; member, the grooves of the two sets being on helices of
Opposite hand. For manufacturing simplicity, the grooves
may be straight and inclined to the rotational axis of the
joint member, instead of being truly helical. Balls are
engaged in the grooves and are held in a cage and because of
the crossed configuration of the grooves the balls are held
in the bisector plane of the joint as the parts of the joint
articulate, to give the joint constant velocity ratio
(homokinetic) properties.
Although the invention has been developed for~ making
outer members for such cross-groove constant velocity joints
20 ~it is applicable generall~y to the manufacture of hollow
articles of the type, hereinafter referred to as being of
the type specified, having at least two grooves in the
internal surface thereof, the grooves having longitudinal
axes of symmetry (as hereinafter defined) which differ (as
hereinafter defined). The article may have at least two
;~ ~ sets of grooves~ wikh the grooves in each set being spaced
~; round the longitudinaI axis of the bore and having
longitudinal axes of symmetry which are the same (as
hereinafter defined), the longitudinal axes of symmetry of
the grooves in one set being dif~erent from the longitudinal
axes of symmetry of the~grooves in the other set.
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By 1ongitudinal axis of symmetry of a groore we ~ean
the imaginary line which is equalIy spaced from the edges of
the groove and which lies in an imaginary surface forming a
continuation of the bore surface and containing said edges.
5When we say that the longitudinal axes of symmetry are
the same we mean that the loci of points moving in
synchronism from the one ends of said axes to the other bear
a fixed relation to one another. Conversely, when we say
that the longitudinal axes of symmetry dif~er we mean that
the loci of such moving points do not lie in a fixed
relation to one another. Thus, for example, the axes could
i be on helices of different hand, or of the same hand and
`~ different pitch or on helices of different pitch and hand.
Some of the axes could be straight and others could be
helical
Presently in the manufacture of outer members for
cross-groove constant velocity joints the blanks are made by
forging, extrusion or some other metal forming method and
the grooves are then machined in the bore. Such machining
operations are expensive in time and equipment besides
removing material. It would be convenient to be able to
form the grooves ln the bore without removal of metal or
even to make them with imprecise grooves which would require
less machining than at present. However since the
longitudinal axes of symmetry of the grooves differ as
defined above a one-piece tool could not be removed from the
; ~bore after the grooves had been formed.
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It is an object of one aspect of the invention to
provide a tool for making hollow articles of khe type
specified and particularly for making outer members of
` constant velocity joints in which machining of the grooves
may be reduced or eliminated.
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The present invention provides a tool for use in the
manufacture of a hollow article of the type specified,
comprising a plurality of elements having portions together
adapted to define a substantially complete external surface
having a con~iguration corresponding to that required in the
internal surface and having formatiorls corresponding to that
required in the internal surface and having formations
corresponding to and adapted to form said grooves~ said
elements including first elements and second elements
interposed between them, and the arrangement being such that
- said portions of said first elements can be withdrawn from
the artiele to leave a space or space to permit said second
elements subsequently to be moved inwardly to disengage them
from said internal surface and withdrawn from the article.
15~y a substantially compleSe surface, we mean one in
which there are no gaps or discontinuities sufficient for
the material of the article to enter during the forming
~ process, and which material would have to be removed
- subsequently, e~g. by machining. By use of the tool
according to the invention, the requirement for finish
machining of the article can be reduced or eliminated.
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Preferably the elements o~ the tool together define an
internal cavity into which an expander member is movable to
hold the elements in their positions in which they define
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the external surface, and from which the expander member can
be withdrawn to permit the first elements of the tool to be
moved inwardly into the cavity prior to their withdrawal~
the side faces of at least said portions of the first
elements, which contact at least said portions of the second
elements being parallel to one another or convergent towards
the outside of the tool.
Inward movement o~ the first elements of the tool prior
to their withdrawal enables the elements to have formations
which form the helical or inclined grooves in the bore of
the article.
Preferably each of said portions of said first elements
has a formation adapted to form one of said grooves of one
set thereof, and each portion of a second element has a
formation adapated to form one of said grooves of another
set thereof which differs from said one set.
In their operative positions, the second elements may
be supported by the side faces of the first elements, rather
than directly by the expander member.
Further details of the tool according to the invention
~-^ 10 are described hereafter.
The invention also provides a press fitted with a tool
into the invention, and further comprising a die through
which a hollow blank having the tool inside it can be
pressed to form the article. A particularly useful form of
blank is also described hereafter.
The invention will now be described by way o~ exampIe
with reference to the accompanying drawings, of which;
Figure 1 is an end view of an outer member of a cross
groove constant velocity ratio universal joint,
constituting an article of the type specified.
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Figure 2 is a section through the joint outer member of
Figure 1.
Figure 3 is an end view of a blank to be used according
to the invention in making the joint outer member.
25Figure 4 is a section through the blank of Figure 3.
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Figure 5 is a section through part of the press
according to the invention, in a first stage of operation.
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Figure 6 shows the press of Figure 5, in a second stage
of operation.
Figure 7 shows the press of Figures 5 and 6, in a third
stage of operation.
Figure 8 is an enlarged view of part of a tool
according to the invention, in section on the line 8-8 of
Figure 9.
Figure 9 is an end view of the tool.
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Referring firstly to Figures 1 and 2, these show the
~o outer member o~ a cross groove constant velocity ratio
universal joint, which is a hollow article with a cylind-
rical internal bore having a number of grooves therein. The
central axis of the cylindrical bore, which is the rota-
tional axis of the joint member in use, is indicated at 100.
The joint member contains two sets of three grooves each,
the grooves being of arcuate cross sectional shape and
having helical longitudinal axes of symmetry. One set of
grooves is indicated at 57j 58, 59 and these grooves are
inclined in an anticlockwise helicaI sense when considered
from above the joint member. The other set of grooves 60,
61, 62 are inclined in a clockwise helical sense when
considered from above the joint member. The longitudinal
axis of sy~metry of each of the grooves is indicated by the
number of the groove with the suffix letter _, such axis of
symmetry lying equidistant from the edges of the groove and
on the imaginary cyIinder indicated by line 101, the
cylinder containing the bore of the joint member.
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At present, in the manufacture of constant velocity
joint outer members such as these, the grooves are machined
in a blank which has been forged or extruded. Because the
grooves are inclined in opposite hands, if they were formed
by a one piece tool during extrusion of the article the tool
would not be able to be removed from the finished article.
The present invention provides a tool which is capable of
being removed from such a joint outer member.
Referring now to Figures 3 and 4 of the drawings, there
is ~shown a configuration of blank which may with advantage
be used with the tool to be described hereafter. It is cup
shaped, with its internal and external walls diverging
towards its free open end. The internal wall 70 is of
generally frusto conical form, with two sets of oppositely
inclined recesses therein. One set of recesses is indicated
at 71, 72, 73, inclined in one direction, and the other set
at 74, 75, 76 inclined in the opposite direction. These
recesses, which are to form the grooves in the finished
joint outer member, are of a configuration such that a one-
piece forming tool can be withdrawn axially from the blank
after the blank has been formed. Forming the blank to the
finished joint outer member is achieved by inserting the
tool to be described hereafter into the blank and forcing
the blank through a die so as to deform the side wall of the
blank inwardly as indicated by arrows 80 ln Figure 4.
Referring now to Figure 5 of the drawings, there is
~ shown a ram 20 of a press to which is secured, by a screw-
-~ 25 threaded connection ring 21, a mandrel 22. The lower end of
~ mandrel 22 has secured to it an elongate cylindrical
;~ expander member 23. A sleeve 24 is slidable longitudinally
o~ mandrel 22,~ between limits determined by a peg 25
extending inwardly from sleeve 24 into a longitudinally
extending slot 26 in mandrel 22. Towards the lower end of
sleeve 24, there is a circumferentially extending flange 27,
and slidable on sleeve 24 below khe flange 27 is a collar
28. The colIar 28 is spring biased upwardly by a plurality
of tension springs 29 spaced around the collar, only one of
which springs is shown in the drawing. The springs 29
engage pins 30 extending into the mandrel 22.
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Within flange 27, the sleeve 24 is provided with three
equally circumferentially spaced radial apertures 31. Each
aperture 31 receives a ball end of a peg 32 extending
outwardly frorn the upper end of an element 33 having a head
34 at its lower end. Circumferentially spaoed about sleeve
24, between the apertures 31, are three slots 35 which
extend downwardly from flange 27. Each slot 35 receives a
peg 36 extending outwardly from the upper end of an element
37 having a head 38 at its lower end. The pegs 36 are long
enough to be engaged by collar 28. The head portions 34, of
elements 33, together define parts of` an internal cavity 40
~ which is frusto conical and in which an end portion of the
-~ expander member 23 is a close fit.
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The shapes of the head portions 34, 38 of elements 33,
37 are shown in greater detail in Figures 8 and 9 of the
drawings. Head portions 34 have formations 34a thereon
which form the grooves of one hand, and head portions 38
have formations 38a which form the grooves of opposite hand
in the joint member. It will be noted that head portions 34
have sides which are parallel or converge slightly towards
-; the~outside of the tool, while head portions 38 interposed
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there between are wedge shaped and are supported by the
;~ sides of head portions 34 rather than directly by contact
with the end portion of the expander member.
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In use of the apparatus, the assembly of elements 33,
37, with the expander member 23 therein, is introduced into
a blank as shown in Figures 3 and 4. The press is then used
to force the blank with the tool within it into a die ~1.
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This has the effect of deforming inwardly the wall of the
blank adjacent its free end, to conform to the surface shape
~ of the assembled tooI elements.
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The tool must then be withdrawn from the formed joint
outer member, and the first stage in such withdrawal is
shown in Figure 6.
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Initially, the open end of the joint outer member is
engaged by suitable gripper means, not shown, to prevent its
upward movement. Thereafter, mandrel 22 is raised by
operation of` the press. Since the elements 33, 37 cannot be
withdrawn together from the joint outer member because of
the grooves therein the sleeve 2~ remains in a fixed
position as the mandrel is raised, until peg 25 abuts the
; lower end of slot 26. During this 7 springs 29 have been
tensioned, while the expander member, fast with mandrel 22,
has been withdrawn clear of the internal cavity of the head
portions of elements 33, 37.
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The elements 33 are now free to tilt inwardly. This
tilting is possible by virtue of the ball ends of pegs 32
engaging in apertures 31. Such tilting permits the head
15 portions to be withdrawn from the joint outer member, with
continued upward movement of mandrel 22. Head portions 38
of elements 37 remain in contact with the joint outer
member, supported by elements 33.
On continued upward movement of mandrel 22, springs 29
20 are tensioned further as pegs 36 on elements 37 move down
slots 35, taking collar 28 down the sleeve 24 with them.
Ultimately a position as shown in Figure 7 is reached, in
which pegs 36 have reached the lower ends of slots 35
s tensioning springs 29 to their fullest extent~ The elements
25 37 are now no longer supported by elements 33~
The condition shown in Figure 7 will not exist more
than momentarily, since there will be a tendency for the
elements 37 to move inwardly as soon as their support by
elements 33 ceases. However, as a consequence of the
30 deformation of the material of the joint outer member, the
elements 37 and indeed, elements 33 at an earlier stage, may
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adhere thereto so that an appreciable force needs to be
exerted, by pegs 36 engaging bottoms of slots 35, before the
elements 37 will remove from the joint outer member. This
is why the joint outer member must be engaged by some form
of gripper. As soon as the elements 37 are clear of the
joint outer member, springs 29 will bring collar 28 upwardly
and return, firstly, the elements 37 to their starting
position. Thereafter springs 29 will bring sleeve 24 along
with collar 28 upwardly to its original position relative to
mandrel 22, and the parts will then regain their relative
positions illustrated in Figure 5.
Although as described the apparatus is used for the
manufacture of the outer member of a constant velocity ratio
universal joint9 it will be appreciated that it is suitable
for manufactur-e of other components of the same general
configuration, having an internal surface with grooves of
different hand therein. There may be other numbers of
elements such as elements 33, 37, according to the shape of
the component to be manufactured.
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Although as described above the tool assembly i3
mounted on the ram of the press and the die is fixed on the
base of the press, it would be possible for the die rather
than the tool assembly to be moved by the press ram. The
relative movements occuring between the parts of the tool
asse-bly and the die would be the same.
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