U.S. patent number 3,747,450 [Application Number 05/173,513] was granted by the patent office on 1973-07-24 for method of perforating tubes.
Invention is credited to Leslie Gordon Hudson.
United States Patent |
3,747,450 |
Hudson |
July 24, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
METHOD OF PERFORATING TUBES
Abstract
The invention relates to a method for forming slots in a section
of a tube of rectangular section comprising inserting a die into
the tube, the die having a width less than that of the tube and
having a recess open on three faces extending across the die, a
punch with a rectangular perforating portion perforating the tube
and aligned with the recess to punch out a blank of material, which
blank splits into two halves which curl away from the recess and
remain secured to the tube.
Inventors: |
Hudson; Leslie Gordon (Epping,
Essex, EN) |
Family
ID: |
10414682 |
Appl.
No.: |
05/173,513 |
Filed: |
August 27, 1971 |
Foreign Application Priority Data
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Aug 20, 1970 [GB] |
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40,393/70 |
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Current U.S.
Class: |
83/30; 83/188;
83/685; 83/54; 83/636 |
Current CPC
Class: |
B21D
28/10 (20130101); B21D 28/28 (20130101); Y10T
83/395 (20150401); Y10T 83/0481 (20150401); Y10T
83/8854 (20150401); Y10T 83/9425 (20150401); Y10T
83/0596 (20150401) |
Current International
Class: |
B21D
28/24 (20060101); B21D 28/10 (20060101); B21D
28/28 (20060101); B26d 003/00 () |
Field of
Search: |
;83/30,54,636,685,688,689,694,188,192-195 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Meister; J. M.
Claims
I claim:
1. A method of forming a slot in a tubular member, comprising the
steps of sliding a tubular member in which the slots are to be
formed onto a die located in a determined position, said die having
a lateral width less than that of the slot to be formed, an
open-ended recess in the said die extending across said die, said
open-ended recess being positioned adjacent the position at which
said slot is to be formed in said tubular member, perforating the
surface of said member with a blow from a punch, whereby a
punched-out blank of material is split substantially into two
halves, and maintaining said halves of said blank secured to the
inner surface of said tubular member at the sides of the lateral
extremity of said slot and turned away from said recess in said
die, whereby a clean slot is obtained in said tubular member with
no loose swarf in said die.
2. A method according to claim 1, wherein said die is secured to
the machine on which said punch is mounted by means of a connecting
bar which passes through said tubular member and is connected at
one end to said die.
Description
The invention relates to a method for perforating slots in a
tubular member of rectangular section, for example. In particular
the method of the invention is used in forming horizontal slots in
one surface of the member at spaced-apart locations. Such
perforated tubular members may then be used to accommodate brackets
or other fittings which support shelves or drawers.
Slots have been formed in tubular members by milling, but this is a
time-consuming operation. The problem of forming slots in a surface
of a tubular member by using a punch and die of the same shape and
size as the slot to be formed has to be overcome. The problem of
forming slots with a punch and die is that the residual blank of
material punched out of the surface of the tubular member cannot be
removed easily from the die as the die is enclosed within the
tubular member during the perforating step. Furthermore, any
irregularities in the inside dimensions of the tubular member, and
in addition the clearance necessary between the die and the inner
surfaces of the tubular member to enable the tubular member to be
moved along the length of the die, prevents accurate location of
the die laterally under the punch during the perforating step.
According to the invention there is provided a method of forming
slots in tubular members, comprising the steps of sliding a tubular
member in which the slots are to be formed onto a die located in a
determined position, which die has a lateral width less than that
of the slot to be formed, an open-ended recess in the die extending
across die, the open-ended recess being positioned adjacent the
position at which the slot is to be formed in the tubular member,
perforating the surface of the member with a blow from a punch, so
that the blank of material is split substantially into two halves
and maintaining the halves of the blank secured to the inner
surface of the tubular member at the sides of the lateral extremity
of the slot and turned away from the recess in the die so that a
clean slot is obtained in the tubular member with no loose swarf in
the die.
The method of the invention therefore prevents the blank of
material punched out of the surface of the material when forming
the slot in the surface of the tubular member from remaining in the
recess in the die by splitting the blank substantially into two
halves, and allows the ends of the two halves to remain attached to
the tubular member in such a way that there is no residual or loose
blank of punched-out material in the die, and thus relative
longitudinal movement between the tubular member and the die is not
prevented. Moreover, as the die is of less lateral extent than the
slot to be formed, and since the recess in the die is open on three
faces, the necessity for accurate lateral location of the die
inside the tubular member is obviated.
Preferably, the die may be secured to the machine on which the
punch is mounted by means of a connecting bar which passes through
the tubular member and is connected at one end to the die.
One embodiment of the invention is diagrammatically illustrated, by
way of example, in the accompanying drawings, in which:
FIG. 1 shows the relative positions of a punch and die, in
perspective, during perforation of a surface of a tubular member of
rectangular section (not shown) to provide a slot;
FIG. 2 shows an end elevation of the rectangular tubular member
after perforation; and
FIG. 3 shows a perspective view of a perforated tube having a
series of horizontal slots formed therein.
Referring to the drawings, the apparatus for perforating a tubular
metal member is shown in FIGS. 1 and 2 and comprises a punch 1
having a shank portion 2 which is flat and has a cross-section
corresponding to that of the slot to be formed and terminates at
the perforating end in a double taper so that it forms a triangular
apex or point, and a die 4 having recess 5 which is open on the
three faces as shown in FIG. 1.
The lateral width of the die 4, and thus of the recess 5, is less
than the width of the slot to be formed in a surface of a tubular
member 6. The width of the slot to be formed is determined by the
lateral width of the punch 1, which is thus wider than the width of
the die. I have found that a die 3/8 inch wide is suitable to form
a slot 1/2 inch wide. It will be understood that the width of the
die should be sufficient to support the surface of the member in
order to obviate denting of the surface during perforation, but
must be narrow enough to allow withdrawal of the die longitudinally
of the member 6.
In use to form a slot in the tubular member 6, the die 4 is placed
in the member 6 so that the surface 7 of the die abuts the
underside 8 of the surface of the member 6, which is thus supported
by the die. The die is held in position so that its upper surface
engages the underside 8, and is secured to the machine on which the
punch is mounted by a bar passing longitudinally through the
tubular member. The punch and die are thus mounted in the same
vertical plane, the punch being aligned with the recess. The punch
is then brought down sharply in a position aligned with the open
recess 5 in the die. A slot 9 is thus formed in the surface of the
tubular member. A blank of material punched from the surface of the
tubular member is cut by the shearing action of the punch into
substantially two halves, which are forced downwardly into the
recess 5. As the recess 5 has no side walls, the two halves of the
blank are pushed apart by the punch and curl away from the slot 9
towards the underside 8 of the surface, and remain attached to the
tubular member at roots 10 and 10'.
The member 6 is then drawn longitudinally of the die without
hindrance while the die is held stationary by the bar passing
through the tube and the punching operation is repeated at another
predetermined position along the length of the tube. A tube having
a plurality of perforations is shown in FIG. 3.
It will be appreciated that a plurality of slots may be formed
simultaneously by providing a die with the required number of
recesses or slots, and a corresponding number of punches mounted in
a hammer (not shown). The punches would each be aligned with one
recess in the die.
The invention thus provides a method of perforating tubular metal
members in which the die is not clogged with loose swarf or blanks
of metal.
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