Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
36iL00
The present invention relates to a process o~
manufacturincJ a trimming die having a conical pol~gonal
aperture which is used in a nut-trimming press equipped with
a cup-shaped fixture for holding the die to calibrate the
width over flats of hexagonal nuts.
A possibility for manufacturing trimming dies is
known (from FR-PS 2 145 357). Here, a cylindrical blank
with a conical axial bore is placed into a holding fixture
of the press. The diameter of the lower aperture of the
conical bore is either as large as, or larger than, the
diameter measured at the corners of the head of a screw obtained
by means of these dies. The holding fixture itself has a
cylindrical bore which goes over into such a conical one whose
conicity, in essence, is the same as that of the punch.
The continuation of the boring in the fixture is cylindrical
' again.
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;, As soon as the blank has been placed into the
cylindrical part of the holding fixture, a punch of hexagonal
cross-section is introduced into the bore of the blank. The
, 20 cylindrical shank of the punch is guided in a ring. This
` ring, whose diameter is not larger than that of the
cylindrical boring in the holding fixture, rests upon the
upper surface of the blank in the process of pressing, while
the punch goes into the conical boring of the blank. In the
' process of further action of the ring and punch, the hexagonal
head will be formed in the blank, under the action of the
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i pressure of the press, the blank goes over into the conical
' part of the holding fixture and, resulting from the flow of
':'! the material, a conical external shape is obtained. With
,i 30 continued pressing process, the material at the lower face
- plate of the blank will also flow into the cylindrical boring,
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being the continuation of the conical one, so that, at the
end po~ition of the punch, the blank will also have a
cylindrical shoulder on one of its face plates besides its
external conical form.
After the punch and the ring have been removed, the
blank can be taken out by turning over the holding fixture.
However, before a die, produced according to the known method,
could be used to produce nuts, a further operation, e.g.,
grinding or turning, is inevitably necessary to remove the
cylindrical shoulder on one o the face plates of the blank
and to turn the cone for obtaining a suitable die with the
xequired dimensions and with a cylindrical external diameter.
This additional work is inevitable since the corresponding
ixture for holding the die in a nut-press is cylindrical.
The scope and aim of the present invention consists
of eliminating the above drawbacks in the production of trim-
ming dies used for producing screws with a polygonal head,
and of producing the dies with the required dimensions without
any substantial additional work.
In accordance with the invention, this problem is
solved in such a manner that the blank for making the trimming
die is produced with an external diameter corresponding with
the internal diameter of the cup-shaped holding fixture, and
; having a height corresponding to the finish size. The blank
has a cylindrical internal bore and the polygonal bore is made
by cold deformation of the diameter of the internal bore by
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i means of a polygonal pressure punch inserted into the internal
- bore in a confined manner whilst retaining the size of the
external diameter of the blank. With the application of this
m~thod, thê appaxatus can manufacture the trimming die without
any additional machining, except for the removal of small burrs
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~ormed on the lower face plate when the punch comes out of
the boring, since the die has exactly the preset external
cylinder diameter, and also the tolerances for the height
and len~th could be preset exactly. In this process, a
compacting of the material takes place, which quite considerably
increases the lifetime of the trimming die, as a result of
widening the bore of the blank. Simultaneously ~he blank is
-Eixed in the holding ixture, between the punch and the
guiding sleeve and between the spacer ring and kicker rod,
fo.rming the bottom of the holding fixture. In addition, the
fo~med die is kicked out under the action of the kicking rod
without any manual operation. According to a bxoad aspect,
the present invention provides a process for manufacturing
trimming dies with a conical polygonal aperture and for use
in a nut-trimming press equipped with a cup-shaped fixture for
holding the die to calibrate the width over flats of hexagonal
~, nuts, characterized in that a blank to form a trimming die is
produced with an external diameter corresponding with an
internal diameter of a cup-shaped holding fixture, said blank
~' 20 having a height corresponding to the height of the finished
die and haviny a cylindrical bore, a polygonal bore is made in
said bore of said blank by cold deformation of the internal :.
diameter by means of a polygonal pressure punch inserted into
. the internal bore in a confined manner while retaining the
- external diameter size of the blank. According to a broad
aspect, the present invention provides an apparatus for
. manufacturing trimming dies characterized by a holding fixture
~ for holding a blank, a spacer ring supported under the blank
; in a bore in said fixture and supported by a bottom of said
holding fixture, a guide sleeve for retaining a polygonal
pressure punch whose length exceeds that of said guide sleeve
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whereby a polygonal internal bore is produced in an internal
bore of said blank when the pressure punch is driven into the
internal bore of the blank, said guide sleeve abutting a top
free face of said blank, at a lower end, and aligning itself
at an upper end with a top face of said punch when the punch
is fully driven into the blank, said holding fixture ha~ing a
kicker sleeve with a relatively movable kicker rod at the
bottom thereof.
According to a further broad aspect of the present
invention there is provided a method for producing a cylindri-
cal trimming die having a conical many-sided internal bore
extending therethrough, for use in a screw trimming press
having a cup-shaped cylindrical holder of a given inner
diameter within which the trimming die is receivable. The
.~ .,
method includes the steps of preparing by machining a
cylindrical blank having an external diameter corresponding
. . .
; to the inner diameter of the cup-shaped cylindrical holder
and an inner bore extending therethrough. The inner bore is
cylindrical for at least the majority of the length thereof,
~ 20 and the height and external diameter of the blank corresponds
to the desired finished height and diameter thereof. The
prepared cylindrical blank is then placed into a cylindrical
bore provided in a holder mounted on a press. The cylindrical
; bore has an internal diameter substantially the same as the
external diameter of the blank. The sidewall of the cylindri-
cal bore engages and confines the cylindrical blank over the
full height thereof. A many-sided punch is then introduced
into the inner bore of the cylindrical blank and the--punch.-: ~
pressed into the inner bore to a predetermined, limited extent-? 30 while the blank is held stationary by the holder, to produce
within the blank a many-sided internal bore by cold deforma--
tion, while preserving the initial, finished external diameter
of the blank. ~ -
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According to a further broad aspect of the present
invention there is provided an apparatus for producing a
cylindrical trimming d-ie having a conical many-sided internal
bore extending therethrough, for use in a screw trimming
press having a cup-shaped cylindrical holder of a given inner
diameter within which the trimming die is receivable. The
trimming die is made from a cylindrical blank having an
external diameter and a height corresponding to the desired
finished external diameter and height of the trimming die,
and provided with an inner bore extending therethrough. The
apparatus includes press means, including a bed, and a
movable press portion operable to be moved toward and away
from the bed. Holder means is mounted on the bed and
provided with a cylindrical bore opening toward the movable
v,~
press portion and having an internal diameter substantially
the same as the external diameter of the blank. The blank
~-~ is receivable within the cylindrical bore and the sidewall
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'-~ of the cylindrical bore is of sufficient height for engaging
and confining the cylindrical blank over the full height
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'~ 20 thereof when the blank is placed therewithin. A many-sided
punch is also provided, the lower end of which is receivable
within the upper end of the inner bore within a blank received
within the cylindrical bore of the holder. The upper end
of the punch is engageable by the movable préss portion for
pressing the punch into the blank to form a many-sided
internal bore therewithin by cold deformation, while the
initial finished external diameter of the blank is preserved.
The holder means is arranged to hold the blank stationary
' during pressing of the punch thereinto.
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As an example for the embodiment, the Figures
illustrate an apparatus for realizing the process in the
invention. ~ere:
Figure 1 is the vertical cross-section with the
various parts required for carrying out -
the process,
Figure 2 is a vertical cross-section with the
various parts in the starting position'
; Figure 3 is a vertical cross~section similar to ;
Figure 2 showing the press punch in the
end~position,
Figure 4 is a formed pressed trimming die. -
It may be seen in Figure 1, the starting material
~1 for the trimming die to be produced is a blank 1 made as a
cylindrical ring with a short conical bore 2 and cylindrical ~-
`~ bore 2a. The diameter of cylindrical bore 2a is smaller than ~`
the size of a screw-head to be obtained with the trimming die.
In order to form the die with a polygonal bore, a blank 1 is --
placed into a holding fixture 3 and gets into`end contact ~,~
' 20 a spacer ring 4, arranged under the blank. The ring 4 is
supported by bottom face 5 of the holding fixture 3. The ;
holding fixture is attached to the press by means of screws 6
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,~ and is equipped with kicker sleeve 7 having a kicker rod 8
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which forms the bottom 5 and which intrudes into the bore of
,~ the holding fixtur~. Conical press-punch 9, having hexagonal
, sections 9a, intrudes into the bore of blank 1. The short
~, conical bore 2 in blank 1 serves to guide the punch 9. The
- cylindrical shaft of press punch 9 works together with sleeve
10, which guides the press punch 9. The length of the polygo-
nal press punch 9 exceeds that of the guide sleeve 10 in
such a manner that a polygonal internal bore is obtained when
the press punch has been driven into internal borings 2, 2a
~i 10 of blank 1 until its free face end 9b aligns itself with the
'a upper annular surface lOa of the guide sleeve 10.
It is, of course, within the ambit of the invention
that the intrusion depth of the press-punch into the int:ernal
bore of the blank could be regulated by means of restricting
the stroke of the press.
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In Figure 2, spacer ring 4, blank 1, and a portion of
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;,~ guide sleeve 10 are in the bore of the holding fixture 3, and
!'```',~'~ the tip 9c of press punch 9, is guided by the short conical
.s,~ ,
boring 2 of blank 1, as it enters into the bore 2a. In this
position, during the following stroke, the press-punch covers
a distance until face plate 9a of press-punch 9 and face plate
lOa of guide sleeve 10 will be in the same plane 11 (Figure 3)
~: and the final size of the internal bore of the blank, i.e.,
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, the ringl has been obtained. The diameter of the bore in the
. . .
holding fixture 3 is the same as that of the spacer ring 4,
, - of the blank 1, of the kicking sleeve 7, and of the guide
; sleeve 10, so that the preset external diameter of the blank,
:,
' i.e., of the trim ring remains exact during the Pressing
~` process.
:;.,
`~ 30 Figure 3 illustrates the end position of the press-
punch 3. An axial pressure acting vertically upon the head of
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the punch (or, in the case of restricting the stroke of the
press, an axial pressure acting simultaneously upon press-punch
9 and guide sleeve 10) drives press-punch 9 through bores 2, 2a, -
thereby obtaining a widening of the internal bore of the blank
1, and a compacting of the material, and of the polygonal
surface. The generated radial forces acting uniformly around
the punch during the material compacting process have no
disadvantageous effect.
After the pressing process has been completed, the
press is retracted, i.e., their pressing plates are moved away
from each other and press-punch 9 and guiding sleeve 10 are
in the free position. Subsequently, a kicking punch 12
provided in the press is actuated. This punch 12 goes into a
blind hole 14, ]ocated on the lower supporting surface 13 of
the kicking sleeve 7, and presses kic]cing rod 8 against
press-punch 9. This willloose the fit between the conical,
polygonally formed part 9a of press-punch 9 and the ring
.
already pressed. Under further actuation o~ kicking rod 12,
;- Xicking sleeve 7 will be pressed against spacer ring 4, i.e., ~ -
~' 20 and consequently against the cornpletely pressed blank. The
, stroke of kicking sleeve 7 and that of the kicking rod 8 above
'~ the depth of blind hole 14 are confined by shoulder 15 of '
~ kicking sleeve 7. As soon as the shoulder 15 gets in contact
:.,
' with the holding fixture 3, the kicking process has been
''~ completed. It is kicking sleeve 7 with kicking rod 8 and
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'i spacer ring 4 overlaying it that are in the bore of the holding
'-- fixture 3.
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Figure 4 illustrates the kicked out ring produced
in this manner. It may readily be seen that, except for some
easy deburring of the lower face plate of the internal bore,
that no further machining is required, and that the ring may
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~ be use~ immediately.
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