1. * GB780096 (A)
Description: GB780096 (A) ? 1957-07-31
Improvements in or relating to methods of manufacturing cocks for
controlling the flow of fluids
Description of GB780096 (A)
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PATENT SPECIFICATION
780,096 Date of Application -and filing Complete Specification: March
7, 1955,.
No. 6685/55.
Application made in France.on March 6, 1954.
Complete Specification Published: July 31, 1957.
Index at acceptance:-Class 83(3), K(2A4J: 7B8X: 7BX: 8).
IntenatiQlnal Classification:-B23c.
COMPLETE -SPECIFICATION
Improvements in or relating to methods of Manufacturing Cocks for
Controlling the -Flow of Fluids I, FRANCOIS JUSTIN DEUpS, of -French
Nationality, of 8 -Rue de la Petite Arche, Paris (16 ), France, do
hereby declare the -invention, for which I pray that a patent may S be
granted to me, and the method by which it is.to be performed, to be
particularly described in and by the following statement:-

2. This invention relates to methods of manufacturing cocks for
controlling the flow of fluids and- has as its object more
particularly to ensure the fluid tightness of such cocks.
According to the present invention there is provided a method of
manufacturing a seating in a cylindrical shut-off member for a cock,
in which the seating is -generated by one milling operation with the
aid of a hollow cylindrical milling cutter having its teeth disposed
on one end thereof, said member and the milling cutter being moved
relative to each other in such a manner, that a cylinder co-axial with
the member and turning therewith, rolls without sliding on a plane
fixed with respect to the axis of the cutter and parallel to, or
containing, the free ends of the teeth of the miling cutter.
For a better understanding of the invention and the method of carrying
the same into effect, reference will now be made to the accompanying
drawings, in which:Figure 1 is a sectional side -elevation of a
shell-type cock, along the line 21-21 of Figure 2, Figure 2 is a
sectional plan view of the shell-type cock shown in Figure 1, Figure 3
is a sectional plan view to an enlarged scale of the shut-off member
taken along the line 11-1 of Figure 1, and shows a milling cutter,
Figure 4 is a sectional plan-view of another shut-off member, Figure 5
shows a detail of the member of Figure 4.drawn-to a larger scale.
Figure 6 is a sectional plan view of a further shut-off member, Figure
7 shows a detail of the member of [Fnc. 3s. 6d.] -Figure 6 drawn to a
larger scale, and Figure 8 is -a diagramnihatic sectional view of a
milling cutter and a part of a shut-off -member being machined, the
section being 50 taken through the cutter axis and showing
two-different positions of the cutter.
In the drawings like references designate -like parts.
Figures 1 and 2 show the construction for 55 a shell-type cock
-having.a rotatable shut-off member 1 located inside a body 2. When
the cock-is in the closed position between the upstream and the
downstream sides, fluid-tightness is obtained by means of rings 60 of
plastic or similar material 4 (there are two such rings illustrated in
the drawings), situated in seatings 3 of suitable shape formed -in the
shut-off member 1.
The seatings 3 and the natural dimensions 65 -of the rings 4 which are
placed therein (i.e.
the dimensions of the ring before its introduction into the seating)
are such that the rings do not tend to escape from their seatings, and
this is -ensured more especially by 70 making each ring of slightly
small dimensions than those of the seating. The ring is made - to bear
both against the rotatable shut-off member and against the body 2, by
virtue of the fact that the amount by which 75 its projects out of the
seating when the shutoff member is isolated from the body is greater

3. than the clearance between the shutoff member and the body. The
pressure ex:erted by the rings on the body is always 80 directed
perpendicularly to the relative movement of the ring with respect to
the body at the point in question.
The cock also comprises in a manner known per se supplementary rings 5
which 85 are intended to ensure a sealing effect between the upstream
and downstream sides -of the body and the exterior of the cock, said
-sealing effect being necessary more particularly when the cock is
being manipulated. 90 A plain pin 6 holds the cock in the correct
axial position; and since the cock -shell is cylindrical, the cock
described is balanced (i.e there is no upward force in the member (1))
and only a small pin is necessary to keep it in position.
The seatings are formed by a milling operation similar to the milling
of gears.
Figure 3 shows this method of production.
A hollow cylindrical milling cutter 20 turns about its imaginary
vertical axis 21. The bottom end of the milling cutter 20 has teeth
23, the lower ends of the teeth being defined by a plane 22 which
together with the axis 24 of the shut-off member 1 is perpendicular to
the plane of the figure. In order to carry out the milling operation,
the shut-off member 1 is arranged in a mounting which causes it to
turn about the axis 24. The milling cutter 20 turns about the axis 21
which is perpendicular to the axis 24, and at the same time is
dispfaced bodily sideways, the axis 21 remaining parallel to its
initial position and the lower ends of the teeth remaining in the
plane 22.
The speed of rotation of the shut-off member about its axis 24 is such
that the plane 22 or an adjacent parallel plane rolls without sliding
over a circumference such as with centre 24 which is tangential to
said plane. It will readily be seen that in this manner a seating is
cut whose depth is delimited by the circumference 25.
In fact the cutting edges of the teeth 23 of the milling cutter
generate developments of circles 30-3 i which constitute the lateral
surfaces of the seatings 3; these seatings have, therefore, the form
of gear teeth gaps the bottoms of which are always limited by the
cylinder whose cross-section is the circumference 25.
It will readily be seen that the cutting edge 26 of the teeth of the
milling cutter generates the profile 30, and the cutting edge 27 the
profile 31.
The milling cutter shown in Figure 3 has cylindrical cutting edges,
but of course it is possible to use any other type of cutter, for
instance a milling cutter with conical cutting edges.
As has alreadly been indicated, the rings -4 are mounted with
pre-tension in their seatings. Consequently, they each bear against

4. the shut-off member 1 especially in the region of those points of
contact between the ring 4 and the member 1 at the tangents common to
the ring and the inner side wall of the seating 3 and drawn from a
point 36 as shown in Figure 3. Said tangents form a cone of angle c.
and it will readily be appreciated that the greater this angle is, the
more strongly will the ring 4 bear against the inside of the seating,
and therefore the better will it remain fast with the shut-off member.
It will be seen, moreover, that the lateral profile of the seating at
the point of contact 65 with the outer limit circumference 34 of the
shut-off member forms an angle fl with the perpendicular to the said
circumference; the value of this angle is so chosen as to prevent any
jamming of the ring when the shut-off 70 member is being operated.
Figure 4 is a sectional view of the shutoff member with a different
profile for the seatings; the developments are replaced by elongated
epicycloidal profiles, and the angle 75 13 has become nil. which is
the most favourable condition for preventing any risk of jamming.
Figure 5 shows, to a larger scale, the profile of the seating of
Figure 4. 80 Figure 6 shows a seating wherein the angle PI has become
negative: Figure 7 shows, to a larger scale, the corresponding
profile.
Ficure 8 indicates how the cutter 20 is employed to form a seating 3
that widens as it 85 deepens. The cutter 20 is shown in two different
positions. In the first position the axis of rotation of the cutter is
at 21A and the plane that is fixed in relation to the axis is shown at
22A. This plane rolls on the 90 cylinder 25A that is concentric with
the member 1. In the second position of the cutter 20, the cutter axis
is at 21B and the plane at 22B. The cutter teeth in the first position
are shown as 23A and in the second 95 position as -23B. During rolling
of the cutter 20, the point A cenerates the curve BC and the edge 26
forms the curve BD. The -edge 27 generates the curve EF and the point
H forms the curve FG. 100 It will be appreciated that the shape of the
section of the seating 3 is largely determined by the value of the
diameter of the cylinder 25A in relation to the diameter of the member
1. 105
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