Note: Descriptions are shown in the official language in which they were submitted.
Dieless Compression Head And
Method of Crimping
by: Neil P. Ferraro
BACKGROUND OF THF TNVENTION
1. Field of the Tnvention
1~ The present invention relates to compressing articles and,
more particularly, to a dieless compression head and a
method of crimping electrical connectors onto conductors.
2. Prior Art
It is well known in the art to termi~aate electric cables by
inserting an end of a cable into a connector wh~.ch is then
compressed or indented so as to form a mechanical and
electrical connection bet~we~n the cable and connector. U.S.
Patent 3, 644,989 to i~Iorby discloses a compression indenting
tool with a piston that carries a punch with the overall
form of a four-sided pyramid. U.S. Patent 4,136,549 to
Lytle et al, discloses a hydraulic ccampression tool with a
dieless compression head used in cr~.mpxng or compressing
connectors to cables. Although dieless compression heads,
also known as universal-compression heads, have been known
and used in the past o crimp a variety of size connectors
and canductors, a problem nonetheless existed in the prior
art in that the universal compression heads were unable to
Grimp all sizes of connectors and conductors with the same
degree of quality. Tn order to p~°operly crimp a relatively
large connector with a relatively large ccanductor, such as a
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1000 MCM wire size conductor, the front of the indentor
needs to be broad to prevent the indentor from inadvertently
piercing through the connector rather than properly
compressing the connector. However, in order to properly
crimp a connector onto a relatively small conductor, such as
a 6 AWG wire size conductor, the front of the indentor
should be narrow such that the indentor can indent the
connector and not merely flatten the connector which would
not produce a good crimp. The prior art universal
compression heads have been unable to adequately support
both of these divergent requirements and provide the same
type of quality connections for a full range of connectors
and conductors sizes.
It is therefore an, objective of the present invention to
overcome problems in the prior art as well as provide
additional features.
SUMMARY OF THE INVENTION
The foregoing problems are overcome and other advantages are
provided by a dieless compression head for use in a
compression tool and a method of crimping an electrical
connector to a conductor.
In accordance with one embodiment of the invention, an
electrical connector crimping tool is provided comprising a
frame, a ram, an anvil, and means for moving the ram
relative to the anvil. The ram is movably mounted to the
frame and has a front with a first portion having two angled
sides, and a second portion having an inc7er.._tinc~ eYten.sion.
The second portion forms a leading tip of theJram and the
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first portion is located longitudinally behind the second
portion. The anvil is connected to the frame and has two
angled sides adapted to be matingly contacted by the ram
first portion angled sides when the ram is advanced into
contact with the anvil. The means for moving the ram can
move the ram relative to the anvil to crimp an electrical
connector therebetween.
1n accordance with another embodiment of the present
invention, a head for a compression tool is provided
comprising a frame, an anvil, and a ram. The anvil is
connected to the frame and has two angled contact surfaces.
The ram is movably mounted to the frame for movement towards
and away from the anvil angled surfaces. The ram has a
~ front with a pyramid shape and two angled side portions
located behind the pyramid shape which are adapted to
matingly contact the anvil angled side portions. The
pyramid shape is suitably sized so as not to contact the
anvil when the ram side portions contact the anvil contact
surfaces.
Tn accordance with one method of the present invention, a
method of crimping an electrical connector to a conductor is
provided. The method includes providing a compression tool
having a compression head with an anvil surface, a ram with
an indenting surface having a general pyramid shape, and
means for stopping forward movement of the ram at a
predeteranined distance of the top of the pyramid shape from
the anvil. The means for stopping forward movement
comprises a forward portion of the ram, located behind the
pyramid shape, being adapted to contact the anvil surface
and stop forward movement of the ram. The method further
comprises advancing the ram from a first position into
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contact with an exterior of a connector, the connector being
sandwiched between the ram and the anvil; deforming the
connector by advancing the ram past its contact position
with the connector; and stopping the forward advancement of
the ram upon the occurrence of a predetermined force between
the ram and anvil. The predetermined force occurs either
directly between the ram and anvil at the means for stopping
movement when crimping a connector and conductor of a first
size,and.-the predetermined force occurs between the ram
and anvil through the connector when crimping a connector
and conductor of a second relatively larger size.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing aspects and other features of the invention
are explained in the following description, taken in
connection with the accompanying drawings, wherein:
Fig. 1 is a plan side view of a hydraulic compression tool
incorporating features of the present invention.
Fig. 2 is a partial schematic cross sectional view of the
compression head of the tool shown in Fig. 1 with the ram at
a first position.
Fig. 3 is a schematic cross sectional view of the
compression head as in Fig. 2 with the ram at a second
position.
Fig. 4 is a side view of the front of the ram shown in Figs.
1 thru 3.
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Fig. 5 is a plan top view of the ram shown in Fig. 4.
Fig. 6 is a partial perspective view of the front of the ram
5 shown in Fig. 5.
DETAILED DESCRIPTION OF THE INVENTION
Referring to Fig. 1, there is shown a plan side view of a
hydraulic compression tool 2 incorporating features of the
present invention. The tool 2 generally comprises a first
handle 4 having a fluid reservoir therein, a second handle 6,
a body 10, and a compression head 12. Although the present
invention is being described with reference to a hydraulic
compression tool, it should be understood that the invention
can be incorporated into any suitable type of compression
apparatus or crimping tool. In addition, any suitable size,
shape, or type of materials can be used.
The hydraulic compression tool 2 shown in Fig. 1, with the
exception of its compression head 12, is essentially
identical to the hydraulic compression tool shown and
described in U.S. Patent 4,947,672 granted to Pecora et al.
on August 14, 1990. The compression head 12 generally
comprises a cylinder body or frame 14 having a hydraulic
cylinder therein, and an indentor or ram 16 movable mounted
to the frame. Connected to the cylinder body or frame 14 is
an anvil 18. The anvil 18 is connected to the frame 14 by
two pins 19 and 20. In the embodiment shown, the second pin
20 is removable from the anvil 18 such that the anvil can
pivot at pin 19 to open an area 22 intended to receive a
connector.
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The anvil 18 is generally comprised of metal with a center
section 24 and two end sections 26 and 27 having slots 28
and 29 for receiving forward legs 30 and 31 of the frame 14
such that the pins 19 and 20 can fixedly mount the anvil 18
to the frame 14. The interior side of the center section
24, adjacent area 22, generally forms the anvil surface 25
of the tool 2 for contacting the exterior of a connector.
In the embodiment shown, the anvil surface 25 includes two
angled side portions or surfaces 32 and 33 with a center
flat portion 34 therebtween at the center of the anvil 18.
The two angled side portions 32 and 33 are angled about 75
degrees relative to each other. However, any suitable type
of angle or shape of the anvil surface 25 can be provided as
further described below.
Ths ram or indentor 16 is generally comprised of metal with
a rear section (not shown) that is capable of being pushed
forward by hydraulic fluid to advance the indentor 16
relative to the frame 14 and anvil 18. As described above,
the ram 16 is movably mounted to the frame 14 for movement
tawards and away from the anvil l8. Referring also to Figs.
4-6, the front 36 of the ram 16 is generally comprised of
two portions or sections; a pyramid section 38 forming the
leading edge to the ram, and an angled side section 40
located longitudinally behind the pyramid section 38. In
the embodiment shown, the pyramid section 38 .is comprised of
a single four sided pyramid 39 with a flat top 42, base 44
and sides 45, 46, 47, 48. In the embodiment shown, ,the
first two opposite sides 45 axed 46 are angled relative to
each other at an angle of about 109 degrees. However, any
suitable angle can be provide as further described below.
In the embodiment shown, extending from the base 44 at
opposite sides 47 and 48 of the pyramid 39 are two flat
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sections 50 and 51. Extending from the base 44 from sides
45 and 46 of the pyramid are two angled surfaces 52 and 53
that form the angled side section 40 of the indentor 16. In
the embodiment shown, the surfaces 52 and 53 have an angle
of about 75 degrees relative to each other., Thus, in the
embodiment shown, the angle of the ram angled surfaces 52
and 53 is the same as the angle of the anvil angled contact
surfaces 32 and 33.
1~ In the embodiment shown, the indentor 16 has a potential
range of motion from a home position as shown in Fig. 2
through to its end of range of motion at a fully extended
position as shown in Fig. 3. At the fully extended position
the angled surfaces 52 and 53 of the ram side section 40
matingly contacts the angled contact surfaces 32 and 33 of
the anvil 18. Thus contacted, the ram 16 is prevented from
further advancement. In the embodiment shown, the pyramid
section 38 is suitably sized and shaped such that when the
indentor 16 is moved to its fully extended position, the
0 pyramid 39 is spaced from the anvil and has a spacing A
between the anvil center portion 34 and the pyramid's top
42. In a preferred embodiment of the invention, the spacing
A is about 0.26 inch. However, any suitable spacing could
be prov~.ded.
The novel configuration of the ,ram front 36 and anvil
surface 25 allows the tool 2 the ability to crimp connectors
onto conductors far both relatively large connectors .and
relatively small connectors, without significant crimp
~ quality variation. Generally, when crimping a large
connectflr onto a large conductor the ram 16 is advanced by
pumping the handles 4 and 6 until the connector is
sandwiched in area 22 between the ram front 36 and anvil
surface 25. The handles 4 and 6 are further pumped with the
ram 16 advancing and deforming the connector with the
conductor. As the ram moves forward, the pyramid 39 presses
into the connector without piercing.the connector. Once the
pyramid 39 is well embedded with the connector, the ,flat
sections 50 and 51 contact the connector to increase the
area of the ram front that is in compressing contact with
the connector. Eventually, due to the increased area of
contact between the ram front 36 and the connector,
ZO insufficient hydraulic pressure in the tool 2 prevents the
ram from achieving sufficient force, because of the
increased area, and being further advanced, thus resulting
in a proper crimp without piercing the conductor.
When crimping small diameter connectors, the flat sections
50 and 51 do not substantially come into play. Basically,
the connector is merely crimped between 'the pyramid 39 and
anvil 18. The depth of the crimp into the small connector
is controlled by the spacing A. As the ram advances the
pyramid 39 indents into the connector. The pressure in the
hydraulic system of the tool 2 never reaches its blow off
pressure to stop crimping until ths~ ram 16 contacts the
anvil 18. As shown in Fig. 3, when the ram 16 contacts the
anvil 18 the pyramid, due ~o its relatively modestly sloped
sides 45 and 4s and its height, does not contact the anvil
18, thus establishing a predetermined spacing between the
pyramid and anvil surface fbr a predetermined crimp and
shape.
It should be noted that the tool 2 blows off on pressure,
not travel distance. Thus, the tool 2 is capable of
crimping range taking connectors. Fox range taking
connectors, however, since the conductor is a smaller size
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than the connector, the ram 16 can obviously advance even
after the flat area 50 and 51 contact the connector until
such time as the connector is suitably crimped onto the
conductor with suitable pressure. Although the anvil
surface 25 has been described above as a wedge shape with
two flat angled surfaces 32 and 33 with a flat section 34
therebetween, it should be understood that any suitably
shaped anvil surface could be provided including curved
surfaces and stepped surfaces. In addition, the anvil
angled surfaces can have any suitable angled so long as the
pyramid 39 is suitably sized and shaped to be spaced from
the anvil surface 25 at the ram°s fully extended position.
Although the means for stopping the forward advancement of
the ram 16 has been described as the abutment of the ram
angled surfaces 52 and 53 meeting the anvil surfaces 32 and
33, it should be understood that any suitable means could be
used to stop the advancement of the ram 16 at its fully
extended position. In addition, although the pyramid 39 has
been described as a four sided pyram:ld with a flat top, any
suitably sYiaped extension at the lading edge of the ram
could be provided and the term pyramid used herein should be
interpreted as such. The indenting extension or pyramid 39
could also be provided on the anvil surface 25 or could be
provided as multiple pyramids:
bet it be understood that the the foregoing description is
only illustrative of the invention. Various alternatives
and modifications can be devised by those skilled in the'art
~0 without departing from the spirit of the invention.
Accordingly, the present invention is intended to embrace
all such alternatives, modifications and variances which
fall within the scope of the appended claims. -
