U.S. patent application number 12/322386 was filed with the patent office on 2009-09-24 for rotating dovetail connection for materials testing.
This patent application is currently assigned to ILLINOIS TOOL WORKS INC.. Invention is credited to James Brittain Smallwood.
Application Number | 20090235755 12/322386 |
Document ID | / |
Family ID | 41087585 |
Filed Date | 2009-09-24 |
United States Patent
Application |
20090235755 |
Kind Code |
A1 |
Smallwood; James Brittain |
September 24, 2009 |
Rotating dovetail connection for materials testing
Abstract
A rotating dovetail connection is provided in order to attach
jaw faces to grips in materials testing. The connection includes a
machined tongue on the jaw face and a corresponding groove on the
jaw face holder. A ball plunger within the holder serves to center
the jaw face and to retain the jaw face in the holder. The jaw
faces can be installed an removed without the use of tools or loose
parts. The rotating dovetail facilitates a secure connection
between the jaw face and the grip while allowing the jaw faces to
rotate.
Inventors: |
Smallwood; James Brittain;
(Milton, MA) |
Correspondence
Address: |
DAY PITNEY LLP;ACCOUNT: ILLINOIS TOOL WORKS INC.
7 TIMES SQUARE
NEW YORK
NY
10036-7311
US
|
Assignee: |
ILLINOIS TOOL WORKS INC.
|
Family ID: |
41087585 |
Appl. No.: |
12/322386 |
Filed: |
February 2, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61069815 |
Mar 18, 2008 |
|
|
|
Current U.S.
Class: |
73/856 |
Current CPC
Class: |
G01N 2203/0423 20130101;
G01N 2203/0268 20130101; G01N 2203/0017 20130101; G01N 2203/04
20130101; G01N 2203/0016 20130101; G01N 2203/0405 20130101; G01N
3/04 20130101 |
Class at
Publication: |
73/856 |
International
Class: |
G01N 3/02 20060101
G01N003/02 |
Claims
1. A connection for materials testing within a material testing
accessory compromising: a holder including a bore and a latching
mechanism; and a gripping mechanism having a tongue insertable into
said bore in said holder, said tongue being at least partially
rotatable within said bore, and a detent configuration for engaging
said latching mechanism.
2. The connection as claimed in claim 1, wherein said gripping
mechanism is held in place by said latching mechanism.
3. The connection as claimed in claim 1, wherein said bore of said
holder is at least partially cylindrical and wherein said gripping
mechanism is free to rotate throughout a range within said bore of
said holder.
4. The connection as claimed in claim 1, wherein said tongue
includes at least one sloped surface to ease installation into said
bore of said holder.
5. The connection as claimed in claim 1, wherein said bore includes
a cross cut pathway sized to allow said tongue on said gripping
mechanism to slide through.
6. The connection as claimed in claim 1, wherein said tongue
includes an undercut which is sized to allow said tongue on said
gripping mechanism be held securely in said holder.
7. The connection as claimed in claim 1, wherein said latching
mechanism is a spring loaded ball plunger passing through a central
longitudinal aperture in said holder.
8. The connection as claimed in claim 1, wherein said gripping
mechanism is a removable jaw face.
9. The connection as claimed in claim 1, wherein said material
testing accessory is a pneumatic, hydraulic, or screw-action
grip.
10. The connection as claimed in claim 1 wherein said tongue
includes lateral flat surfaces.
Description
[0001] This application claims priority under 35 U.S.C. 119(e) from
U.S. provisional patent application Ser. No. 61/069,815, filed on
Mar. 18, 2008, the contents of which are hereby incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention pertains to a device for use in
material testing equipment and accessories. More specifically, the
present invention pertains to a mechanism for the connection of
removable jaw faces to material testing grips.
[0004] 2. Description of the Prior Art
[0005] In the prior art, materials testing systems are used in a
variety of industries and are generally used with some sort of
accessory to provide specimen gripping or holding. Many of these
tests require that the accessories have specific gripping surfaces
or sizes. The size and type of gripping surface needed can vary
greatly from test to test, making jaw face changes a frequent event
in many labs. Therefore, removable jaw faces with various sizes and
surfaces are a common commodity in the materials testing
industry.
[0006] Many different embodiments of jaw face attachment have
developed over the years by various manufacturers. These connection
mechanisms include simple pin and aperture connections as well as
rigid dovetail connections. Each mechanism has advantages and
disadvantages.
[0007] Zwick has implemented the use of a rigid dovetail connection
as shown in FIG. 1. This connection method allows for a repeatable
location for the jaw face while allowing for ease of installation.
Rotation of the jaw faces is not possible with this method
rendering fixed the position of the jaw faces relative to the
gripped specimen. Furthermore, a tool must be used to connect these
jaw faces to their holders.
[0008] MTS has implemented an externally accessible pin and a
corresponding aperture to connect the jaw faces to the grips as
shown in FIG. 2. This allows for jaw face rotation but poses a
potential safety issue because the protruding heads and rings of
the pins also move in conjunction with the jaw faces. The pull
rings used for removing the pins may also get entangled in the
grips. External pins may also be ejected from the apertures if
measures are not taken to retain them in the grips. It appears that
this has been addressed with the addition of an O-ring to the end
of the pin. Additionally, the pins are a loose part which may be
easily lost.
[0009] Instron, the assignee of the present application, has
implemented four jaw face to grip connection methods of interest.
These method include set screw and groove; internal pin an
aperture; internal pin and retaining wire; and hook and fixed pin.
All of these methods allow the jaw faces to rotate. This rotation
is needed to compensate for both inconsistencies in specimen
thickness and elastic deformation of grip bodies during testing.
The set screw and groove method as shown in FIG. 3 is a simple and
inexpensive method that requires a tool for installation. The set
screws provide the pivot point for jaw face rotation. Faces
typically rotate slightly in all directions with this connection
method.
[0010] The internal pin and aperture method as shown in FIG. 4 has
been perhaps the most common jaw face connection method used to
date and has been adopted by various competitors. While this is
perhaps the least expensive and least complicated method, there are
some drawbacks. For instance, installation often requires an
experienced user or an additional person to hold and manipulate the
various components. Additionally, the pins may not maintain their
positional integrity during testing. A slight displacement may
typically be remedied by the retraction of the holders into the
grip body, but occasionally it results in the pin and jaw face
falling partially or completely out of the holder. Another drawback
is that the pins are small loose parts which can be easily dropped
or lost.
[0011] The internal pin and retention wire method was developed by
the present assignee for use on side-acting screw action grips and
uses a semi-permanent pin installed in the back of a typical pin
and aperture jaw face as shown in FIG. 5. This assembly can be
snapped into the holder using one hand and without the use of any
tools. To remove the jaw face, simply unscrew the holder until the
retention wire opens up. The jaw face can now be easily removed.
While this method allows for simple installation and predictable
usage patterns, there are some drawbacks associated with it.
Firstly, the retention wire and holder both require special
detailed machine to get the correct feel and action. Secondly, the
semi-permanent pin represents a small loose part that can get
lost.
[0012] On higher capacity pneumatic side-action grips, the present
assignee has implemented the use of a hook and fixed pin connection
method as shown in FIG. 6. A fixed pin is pressed into the back of
a specially machined jaw face and acts as an attachment point for a
corresponding spring-loaded hook that resides inside of the grip.
Attaching the face to the grip requires that the user insert a tool
onto the grip to move the spring-loaded hook far enough to slide
the face over it. When the hook retracts back into the body, the
face is firmly held on the grip. This eliminates loose parts, but
necessitates the use of a tool for installation and removal. This
apparatus further requires unique detailed faces and holders.
OBJECTS AND SUMMARY OF THE INVENTION
[0013] It is therefore an object of the present invention to
provide a connection apparatus for materials testing which is easy
to operate, is robust, and provides repeatable jaw face
positioning.
[0014] It is therefore a further object of the present invention to
provide a secure rotating jaw face connection to be used in
material testing accessories which substantially eliminates the
complexity and difficulty involved in installing and removing jaw
faces.
[0015] It is therefore a still further object of the present
invention to reduce or eliminate the need for tools in the assembly
and disassembly of the connection apparatus for materials testing,
while maintaining secure operation of the apparatus.
[0016] These and other objects are attained by providing a rotating
dovetail connection for use on materials testing accessories that
use removable jaw faces. This rotating dovetail connection is
related to the dovetail joinery connection that allows for a secure
sliding connection in carpentry without the use of auxiliary parts.
Adapting the tongue and groove of the joint into a rounded edge
permits the connection to rotate while still being held securely
together. This is particularly useful in jaw face attachment where
slight rotation of the jaw faces is desired. The tongue also has a
detent machine into the back side to permit a spring loaded ball to
hold the jaw face securely and accurately in the holder. The degree
of rotation is controlled by the placement of the groove in
relation to the back of the jaw face. Another embodiment machines
flats and a cross aperture on the jaw face for to allow use in
grips that use the pin and aperture connection method.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Further objects and advantages of the invention will become
apparent from the following description and from the accompanying
drawings and claims, wherein:
[0018] FIG. 1 illustrates typical prior art dovetail connection
apparatus.
[0019] FIG. 2 illustrates typical prior art external pin and
aperture connection apparatus.
[0020] FIG. 3 illustrates typical prior art set screw and groove
connection apparatus.
[0021] FIG. 4 illustrates typical prior internal pin and aperture
connection apparatus.
[0022] FIG. 5 illustrates typical prior art internal pin and
retention wire connection apparatus.
[0023] FIG. 6 illustrates typical hook and fixed pin connection
apparatus.
[0024] FIG. 7 is a side view of the rotating dovetail connection
assembly of an embodiment of the present invention.
[0025] FIG. 8 is an exploded isometric view of the rotating
dovetail connection assembly of an embodiment of the present
invention.
[0026] FIG. 9 is a cross-sectional view of a holder of an
embodiment of the present invention.
[0027] FIG. 10 is a plan view of the rotating dovetail gripping
mechanism of an embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0028] Referring now to the drawings in detail wherein like
numerals refer to like elements throughout the several views, one
sees that FIG. 7 shows the rotating dovetail connection 10 which
includes cylindrical holder device (or holder) 12, the gripping
device 14 (which can be configured as a removable jaw face), and
the threaded latching mechanism 16, configured as a spring-loaded
ball plunger. Other possible configurations of latching mechanism
16 include a press-in plunger without threading. As shown in FIGS.
7 and 8, the rotating dovetail connection 10 is compromised of
these three parts 12, 14, 16. The direction of rotation is also
shown in FIG. 7.
[0029] As shown in FIG. 8, the gripping device 14 includes plate 17
and tongue 18. Tongue 18 further includes a detent 20 on inner face
22 and a cross aperture 24 passing through tongue 18 parallel to
plate 17. Cross aperture 24 is oriented vertically in FIG. 8. The
detent 20 is engaged by latching mechanism 16 which is configured
as a spring loaded ball plunger. The spring loaded ball plunger 16
both accurately locates and secures the gripping device 14
relatively to the cylindrical holder device 12. The cross aperture
24 in the gripping device 14 serves as a connection point for a
traditional pin and aperture connection, allowing for the gripping
device 14 to be used on accessories with this connection style. The
gripping device 14 also utilizes a sloped surface 26 on an end (or
ends) of tongue 18 on to better facilitate insertion of the
gripping device 14 into the holding device 12.
[0030] The cross-sectional view of the holding device 12 in FIG. 9
illustrates the details needed for the female end of the rotating
dovetail connection 10. A transverse circular bore 30 is formed in
the cylindrical holder device 12. A cross cut 32 is formed to
create a space for the gripping device 14 to slide into the
cylindrical holder device 12. A central longitudinal aperture 34 is
formed to accept the latching mechanism 16. Holding device 12 can
be engaged by a materials testing accessory, such as a pneumatic,
hydraulic or screw-action grip.
[0031] The profile of the gripping device 14, which exhibits the
male end of the rotating dovetail connection 10, is shown in FIG.
10. The inner face 22 includes a rounded portion 40 on the end of
the tongue 18 with a radius corresponding to that of the bore
radius of transverse circular bore 30 of the is similar in radius
to the matching bore radius on the cylindrical holder device 12.
Tongue 18 further includes undercut 42 immediately adjacent to
plate 17. Undercut feature 42 serves to secure the gripping device
14 within the cylindrical holder device 12 from moving laterally in
the negative Z direction as shown on FIG. 10. Additionally, the
lateral flat portions 44 on the tongue 18 allow the gripping device
14 to be used on prior art pin and aperture equipment.
[0032] When the rotating dovetail connection 10 is not put under
any extraneous load, the ball plunger 16 forces the gripping device
14 in the negative Z direction against the transverse circular bore
30 of the holder device 12. When an extraneous load is applied to
the gripping device 14 in the positive Z direction, the ball
plunger 16 is compressed, the rounded surface 22 mates up with the
transverse circular bore 30, and the connection is free to rotate
about the X-axis in FIG. 10 (Y-axis in FIG. 9).
[0033] Thus the several aforementioned objects and advantages are
most effectively attained. Although preferred embodiments of the
invention have been disclosed and described in detail herein, it
should be understood that this invention is in no sense limited
thereby and its scope is to be determined by that of the appended
claims.
* * * * *