Note: Descriptions are shown in the official language in which they were submitted.
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TRUSS JIGGING SYSTEM
Background of the Invention
This invention relates generally to a jigging
system for work pieces and, in particular, to a jigging
system for the assembly of wooden trusses for use in
building.
The invention relates to an improvement to that
disclosed in our Australian Patent No. 694642 (U. S. Patent
No. 5,854,747).
Wooden trusses generally comprise a number of
wooden components including a bottom chord, upper chords
which are generally arranged in a V-shaped configuration,
and connecting pieces or webs between the chords. The
chords and connecting webs are joined together by metal
connector plates which are usually forced into the wooden
components at joints between components on both sides of the
truss by a suitable press or the like. Conventionally, the
components from which the truss are to be made are laid out
on a table which has stops (often referred to as pucks) for
setting the position of the chords.
The above-mentioned Australian patent discloses an
automatic method of moving the stops or pucks to desired
locations to set the position of the chords which are to be
joined together to form the truss. The formation of the
truss from the chords also requires the placement of various
tools such as a peak or apex tool and clamp tools in order
to define the position of the peak or apex and hold the two
chords, which will be joined together to form the apex, in
position. Heel tools are also required in order to define
the points at which the upper chords will intersect with the
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bottom chord. The location of these tools is performed
manually by locating the tools in position on the table
before or after the stops have been automatically moved to
define the position of the chords.
The need to manually locate the tools increases
the time required in order to set up the jigging system for
formation of a truss and therefore the time required in
order to actually produce a truss.
According to the present invention, there is
provided a jigging system for use in arranging components to
form an assembly, the jigging system comprising: an upper
platform having spaced apart slots therein; at least one
tool carriage mounted in one of said slots for sliding
movement relative to the upper platform along said one slot;
a tool adapted for connection to said one carriage for
movement with said one carriage along the slot, the tool
being capable of locating at least one of said components
with respect to the upper platform; the tool and carriage
being constructed for releasable, snap-in connection of the
tool in the carriage so that said one carriage is capable of
carrying multiple tools.
Brief Description of the Drawings
A preferred embodiment of the invention will be
described, by way of example, with reference to the
accompanying drawings, in which:
Figure 1 is a perspective view of a jigging system
according to the preferred embodiment of the invention;
Figure 2 is a greatly enlarged, fragmentary top
plan view of the table showing a puck, but with the truss
shown in Fig. 1 removed for clarity;
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Figure 3 is a section taken in the plane including
line 3-3 of Fig. 2;
Figure 4 is a section taken in the plane including
line 4-4 of Fig. 2;
Figure 5 is a fragmentary plan view similar to
Fig. 2, but showing an apex tool;
Figure 6 is a section taken in the plane including
line 6-6 of Fig. 5;
Figure 7 is a plan view showing a clamp tool;
Figure 8 is a fragmentary plan view of a guide
rail of the preferred embodiment of the invention;
Figure 9 is a section taken as indicated by line
9-9 of Fig. 8;
Figure 10 is a schematic view of a control system
for controlling the jigging system of Figures 1 to 9;
Figure l0A is a diagram illustrating how a
carriage is moved along the table according to one
embodiment of the invention;
Figure 11 is a fragmentary plan view of part of
the table showing a heel tool according to a further
embodiment of the invention;
Figure 12 is an enlarged top plan view of the heel
tool;
Figure 13 is a side view of the heel tool; and
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Figure 14 is a section taken in the plane including
line 14-14 of the heel tool of Fig. 12.
Detailed Description of the Preferred Embodiment
With reference to the drawings, an assembly table 10 is
shown. Tables of this type may typically be up to 30 meters
(100 feet) in length and 4.2 meters (15 feet) in width. The
table 10 has an upper platform generally indicated at 12,
formed from solid sheets 12A or sections or the like which
are spaced apart to define a plurality of slots 14 which, in
the embodiment of Figure 1, extend across the width of the
table. Rather than extend across the width of the table as
shown in Figure 1, the slots 14 could also extend lengthwise
or at an angle across the table if desired. The upper
platform 12 constitutes a reaction surface in the preferred
embodiment.
Arranged for movement along the slots 14 in a manner to
be described hereinafter are a plurality of stops or pucks
19. Typically, the shape of a truss 20 is known and its
details are fed into a control system 30, which controls
movement of the pucks 19. The pucks 19 are then moved in a
manner which will be described hereinafter to positions
needed to locate the truss components for forming the truss
20. In the preferred embodiment of this invention, some of
the slots 14, rather than being provided with pucks 19 are
provided with other jigging tools. Such jigging tools may
include apex tools 19' and clamp tools 19 " , described
hereinafter. It is to be understood that "tools" as used
herein includes the pucks 19, as well as apex tools 19',
clamp tools 19 " or other suitable jigging tools. Such tools
are necessarily arranged on the table 10 to define a jig for
assembling the truss. Chords 20A, 20B and 20C from which
the truss is to be formed are laid out together with webs
20D, with the chords abutting the pucks 19. Connector
plates C are located in generally opposed relation on top
and bottom of the truss 20 at the joints of the chords 20A,
20B and 20C and the webs 20D, and the connector plates are
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driven into the truss 20 in a suitable manner such as by
presses or the like (not shown) to form the truss 20. The
truss 20 is removed from the table 10 and new components,
such as new chords which are the same as those referred to
above, are located in place to form a new truss. If the
shape of the new truss is different, the jig tools 19, 19',
19 " are first moved under the control of a control system
30 (Fig. 10) to new positions for locating truss components
of the new truss.
Figures 2 to 4 are detailed views showing two adjacent
table sections 12A separated by one of the slots 14. A
carriage 100 is arranged within the slot 14 and is moved by
a motor M and flexible endless belt 52 (Fig. l0A). The
details of the motor M and belt 52 are fully disclosed in
our previously mentioned Australian patent, and will only be
briefly described hereinafter. Suffice it to say that the
carriage 100 is secured to the flexible belt 52 described in
the above mentioned patent for movement along the slots 14
as the belt is driven back and forth by the motor M. There
are preferably two carriages per slot 14.
The carriage 100 has a top plate 102 which is supported
on steps 106 and 108 of a guide rail 130 by blocks 110 which
are attached by welding or the like to the top plate 102.
The top plate 102 supports a puck 19. Alternatively, the
carriage 100 can carry another tool such as an apex tool 19'
(Figure 5) for defining the apex of the truss to be formed
or a clamp tool 19 " (Figure 7). The apex tool 19' and clamp
tool 19" will be described in more detail with reference to
Figures 5 to 7.
Referring again to Figs. 3 and 4, the carriage 100
further includes a carriage guide 120 located below the top
plate 102. The carriage guide is guided in the guide rail
130, in which are defined four channels 131, 132, 133 and
134. The rail 130 is supported by a frame (not shown)
beneath the table sections 12A and has inwardly projecting
flange portions 171 which define the steps 106 and 108 with
the sections 12A. The carriage guide 120 is of generally
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box construction having side walls 121 and 122, top wall 124
and bottom wall 123. The top wall 124 has extending flanges
128 and the bottom wall 123 has extending flanges 129. The
flanges 128 and 129 ride in the channels 131 to 134 on
5 plastic strips 141 to facilitate sliding movement of the
carriage 100 along the rail 130. The carriage guide 120 is
secured to the flexible belt 52 (see Figure l0A) which is
driven by the motor M and drive rollers 46, 46' (as
disclosed in our previously mentioned Australian patent) so
that the carriage 100 is driven along the guide rail 130.
The top wall 124 of the carriage guide 120 carries a
cylindrical sleeve 125 having an internal annular upper
bushing 127 and an internal annular lower bushing 126 which
have a space 144 between them. The puck 19 is provided with
a pin 140 which projects downwardly from the underside of
the puck. The pin 140 has a circumferential groove 149 in
which is located a split ring retainer or circlip 142
(broadly, "resilient locking member") when the puck 19 is
connected to the carriage 100. Top plate 102 is provided
with a hole 161 and the pin 140 passes through the hole and
into the sleeve 125 which is aligned with the hole.
As the pin 140 moves downward past the upper bushing
127 an into the space 144, the pin engages the inner
diameter of the circlip 142. The leading end of the pin 140
is tapered, but the main portion of the pin has a diameter
larger than the inner diameter of the circlip 142 so that
the circlip is resiliently deflected outward from its
relaxed position. When the groove 149 of the pin reaches
the space 144, the circlip 142 snaps into the groove,
attaching the pin 140 to the carriage. Further movement of
the pin 140 axially of the sleeve 125 is resisted by
engagement of the circlip 142 with the upper or lower
bushings 127, 126 at the boundaries of the space 144. Thus,
the pin 100 snaps into a releasable locking engagement with
the carriage 100 upon insertion into the sleeve 125. The
pin 140 also couples the top plate 102 to the carriage guide
120. Thus, when the carriage guide 120 is moved by the
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flexible belt 52 along the slot 14, the top plate 102 and
puck 19 are moved conjointly with it. As will be apparent
from Figures 2, 3 and 4, the top plate 102 slides on
shoulders 106 and 108 via blocks 110 as carriage guide 120
and top plate 102 move.
A resilient truss component support 150 connected by
the pin 140 to the carriage 100 holds a chord (such as the
chord 20B shown in Fig. 3) above a top surface of the upper
platform 12 of the table 10. The support 150 comprises a
metal spring plate 152 which has a hole 154 through which
the pin 140 passes to that the plate 152 is secured to the
carriage 100 on the top plate 102 by the pin 140. The
spring plate 152 extends substantially the length of the top
plate 102 and rests at its ends on the top plate 102. A
raised central ("second") portion 155 is higher than the
level of the table sections 12A. Many or all of the
carriages 100 carrying a puck 19 have the support 150 so
that the supports collectively hold the chords 20A-20C and
webs 20D off the upper platform 12. Thus, the truss chords
20A-20C are supported above the level of the assembly table
sections 12A so that tooth connector plates C can be
positioned on the sections 12A beneath the chords 20A-20C.
The left heel of the truss 20 is broken away in Fig. 1 to
reveal a connector plate C located on the bottom side of the
truss. Bottom side connector plates (not shown) are
similarly located at the other joints of the truss 20.
The support plate 152 is formed from a resilient spring
metal and has an end flange 153 which extends over the end
of top plate 102 and into slot 14 so that the spring plate
152 cannot be inadvertently rotated relative to the top
plate 102, and the spring plate 152 can be maintained in the
operative position shown in Figures 2, 3 and 4 for
supporting a chord 20B. Any tendency for the plate 152 to
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rotate in the directions indicated by double headed arrow A
in Figure 2 will be prevented by the sides of the flange 153
contacting side walls 12B of the sections 12A.
The spring metal plate 152 holds the chords 20A-20C in
a position slightly above the top of the upper platform 12.
Thus, connector plates can be slid, teeth up, under the
chords 20A-20C and webs 20D at joint locations, or put in
these locations prior to placement of the chords and webs on
the upper platform 12. Connector plates are also placed on
top of the chords and webs at the joints. To attach the
connector plates to the chords 20A-20C and webs 20D, a
suitable press (not shown) applies a downward force to the
chords, webs and connector plates. The force of the press
overcomes the spring force of the metal spring plates 152,
deflecting the central portion 155 and pushing it down so
that the top surface of the sections 12A of the upper
platform 12 can provide a rigid reaction surface opposing
the action of the press. The teeth of the connector plates
are driven by the press into chords 20A-20C and webs 20D as
a result of the reaction force provided by the upper
platform 12. The spring plates 152 resume their prior
configuration as soon as the press force is released. In
this way, the carriage 100 is protected from experiencing
the high loads from the press while permitting placement of
connector plates under the chords and webs.
Figure 5 shows a plan view similar to Figure 2 except
that an apex tool 19' for positively locating the apex of
truss 20 is shown. The apex tool 19' has a base plate 250
(closely similar to top plate 102) which is provided with a
hole 252. The base plate 250 has a block 110' (Fig. 6) at
each end which ride on steps 106 and 108 of the guide rail
130 in the same manner as the blocks 110 attached to the top
plate 102 of the carriage 100 described with reference to
Figure 4. An apex tool cross-member 251 is attached as by
welding to the base plate 250 so the base plate (with the
blocks 110') and cross-member are a single unit. The cross-
member 251 carries a retractable locating finger 253 which
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has a side edge 254. The side edge 254 positions an angled
end 255 of chord 20B of the truss 20 (shown in phantom) so
that the chord can be correctly located in place at the apex
of the truss. The apex tool 19' is moved to the desired
position by carriage 100 (as describe above for puck 19) so
as to locate the locating finger 253 and therefore the edge
254 in the required position. When the chord 20B is
positioned, the locating finger 253 can be withdrawn (as
indicated in hidden lines in Fig. 5) so that the other upper
chord 20C can abut against the end of the chord 20B to
thereby position the chord 20C. The structure and mode of
operation of the member 251 is conventional and therefore
the apex tool 19' will not be shown or described in any
further detail.
As best shown in Figure 6, the blocks 110' of the apex
tool 19' ride on the steps 106 and 108 which are formed at
the ends of the portions 171 of the guide rail 130. In this
embodiment, the upper plate 102 (with its attached blocks
110) of the carriage 100 is removed by simply removing the
pin 140 which attaches the top plate 102 to the carriage
guide 120 and lifting the top plate 102 out of the slot 14.
The base plate 250 is then placed in the slot 14 on the
steps 106 and 108 and the hole 251 aligned with sleeve 125
of the carriage guide 120. A pin 257 is then pushed through
the aligned hole 251 and the sleeve 125 so that the pin 257
secures the apex tool 19' to the carriage guide 120 in
exactly the same manner as the pin 140 secures the puck 19
to the carriage guide 120 described with reference to Figure
4. In Figure 5, a pin 140 can be provided by one of the
pucks 19 previously described. However, in the embodiment
shown the pin 257 is a separate pin which is similar to the
pin 140 except that the head 259 is substantially flat since
the pin 257 need not form the function of the puck 19.
Figure 7 shows an embodiment in which a clamp tool 19"
is automatically moved by the carriage 100. In this
embodiment, the top plate 102 is located in position in the
same manner as described with reference to Figures 3 and 4.
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The clamp tool 19" is secured to the top plate 102 by the
same type of pin 257 described with reference to Figures 5
and 6 and which passes through a hole 261 formed in the
clamp tool 19 " . However, once again, a puck 19 having the
pin 140 could be used instead of the pin 257. The clamp
tool 19" is pivotal about the pin 257 to arrange the tool
at right angles with respect to a chord 20C so that a clamp
head 260 can engage the chord 20C to push the chords 20A-20C
and webs 20D together. Since the clamp tool 19 " is at
right angles to the chord 20C, load applied by the chords
against the clamp head 260 is in the direction of ram arm
262 and therefore does not tend to rotate the clamp 19" on
pin 257. The clamp tool 19" is of known design except of
the inclusion of a hole through which the pin 257 can pass
to secure the clamp tool 19" to the top plate 102 of the
carriage 100.
It should be understood that in some embodiments of the
invention, the carriage 100 is made up of the carriage guide
120 and the top plate 102. In other embodiments, the top
plate 102 is effectively incorporated into the tool (such as
the plate 250 which forms part of the apex tool 19') and
therefore the carriage is effectively comprised of the
carriage guide 120 and the tool defines the top plate (such
as plate 250) and blocks (such as blocks 110') connected to
the plate 250 which slide on the steps 106 and 108 on the
guide rail.
Figures 8 and 9 illustrate in more detail the
configuration of the guide rail 130. As best shown in
Figures 8 and 9, the guide rail 130 is formed from two
inverted L-shaped rail members 301 which are arranged in
face to face or mirror image relationship with respect to
one another. The rail members 301 have the inwardly
projecting flange portions 171 which, together with the
sections 12A define the steps 106 and 108 upon which the top
plate 102 or the base plate 250 of the apex tool 19' ride.
The flange portions 171 are supported by side walls 302.
The side walls 302 are coupled together by a plurality of
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lower plates 135 which are welded to lower edges of the side
walls at locations spaced along the length of the guide rail
130. The flanges 171 also each have spaced apart holes 307
which facilitate bolting of the sections 12A of the platform
5 12 to the flanges.
Elongate bars 305 are welded to the inner surfaces of
the side walls 302 of the guide rail 130 so as to define the
channels 131, 132, 133 and 134. Some of the plates 135
carry sleeves 311 so that jacks or other suitable supporting
10 structure (not shown) can be engaged with the sleeves to
support the guide rails 130 above ground level. I-beams
(not shown) may be provided between adjacent guide rails 130
for supporting mid portions of the sections 12A. The I-
beams are attached to a conventional frame of the table 10.
Thus, the sections 12A of the upper platform 12 are
supported by the guide rails 130 as well as additional frame
members formed at least partly by the I-beams (not shown).
A jig tool 19, 19' or 19 " may be secured to the top
plate 102 and carriage 120 which covers substantially the
entire plate 102. If the support of the chord 20B at that
particular top plate 102 is not required, the spring plate
152 can simply be lifted up slightly so as to raise the
flange 153 above the top surface of the sections 12A and
then the plate 152 can be rotated about the pin 140 into a
position 180° from that shown in Figures 2 and 3 to move the
spring plate 152 into a non-operative position and out of
any interference with the tool to be supported on the top
plate 102. For example, the spring plate 152 could be moved
into the non-operative position as shown in phantom in
Figure 7 so that the central portion 155 does not interfere
with correct positioning of the clamp tool 19 " relative to
the top plate 102 and the chord 20C. This enables the
spring plate 152 to be moved out of the way while retaining
the spring plate on the apparatus for convenient
repositioning should the respective carriage 102 again be
required to support one of the chords 20A-20C above the
platform 12. Retention of the spring plate 152 on the
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carriage 100 also prevents misplacement of the spring plates
or accidental loss of the spring plates when they are not in
use.
Figures 10 and l0A schematically illustrate the control
system 30 for controlling the jig. The control system 30
includes a portable computer PC which is coupled to a
controller 80. The controller 80 is then in turn coupled to
motor M, encoder 68 and also controls solenoid 70 and disc
brakes 66. One controller 80 can be used to control, for
example, six pucks 19, six other jig tools (e. g., 19',
19 "), or some combination of pucks and other tools. In the
instance where the table 10 has forty-two tools (including
pucks 19), seven controllers 80 connected to the PC for
controlling the jig are used. The controller 80 which
controls each set of six tools (19, 19' or 19 ") will also
control the associated motor M, encoder 68, brakes 66 and
solenoid 70 associated with those tools.
Each of the controllers 80 therefore is controlling six
of the tools (19, 19' or 19"). The controller 80 obtains
information identifying the position of each of the tools
which it is to control. The information is fed to the
controller 80 from the encoder 68 on the pulleys 46. It
should also be noted that all of the tools could be under
the control of a single controller 80 rather than a number
of controllers and all driven simultaneously to their
desired positions under the command of the controller 80.
Conceivably, a greater number of controllers could be
employed.
In the preferred embodiment, information relating to a
truss layout is fed into the PC and that information is then
provided to the controller 80. Initially, the tools 19,
19', 19 " are moved to a zero position by the controller 80.
The controller 80 selects one of the tools, e.g., one of the
pucks 19, and knowing the position of the puck 19, it will
compare the required position to the actual position of the
puck. A command is issued from the controller 80 to the
brake 66 associated with the relevant puck 19 so that the
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brake is released. An output is supplied to solenoid 70 to
ensure that the shaft 60 is moved axially into the position
so that the spline 62 or 64 engages the appropriate pulley
46 and a voltage is supplied to the motor M to drive the
shaft 60 at high speed. The shaft 60 rotates the pulley 46
to drive the appropriate belt 52 about the pulleys 46 and 48
to move the carriage 100 to the desired position to
correctly position the puck 19.
When the puck 19 comes to within a specified distance
from its required position (which may be indicated by a
number of counts issued from encoder 68) the motor speed is
switched to low speed by the controller 80. Typically this
will occur after one or two seconds of running. Again, when
the puck 19 is within the specific number of counts of the
actual position required, the controller 80 issues a signal
to disc brake 66 to apply the brake to stop the pulley 46 so
that the tool 19 comes to rest at the required position.
The motor M is then switched off. The specific number of
counts at which the motor is reduced to low speed and at
which the brake is applied can be determined by the system
response time and could be adjustable and preset in the
controller 80. The controller then selects another tool
(19, 19' or 19 ") so that the next tool can be moved. The
solenoid 79 is operated to disengage splines 62 of the shaft
60 from the pulley 46 and to engage the other spline 64 with
its pulley 46'. The same procedure as outlined above is
_ then repeated to position the other tools.
For any truss configuration only some of the tools 19,
19', 19" which may be provided may be used. Those tools
which need not be used for a particular truss configuration
can be controlled so that they are moved to the edge of the
table so that they are completely out of the way of the
truss 20 which is to be manufactured.
In the preferred embodiment of the invention, the pucks
19 are coupled to top plates 102 and carriages 120 by a pin
140 so that the pucks 19 can be released from any of the
respective carriages in a similar fashion to the tools 19',
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19" . The tools 19, 19', 19" are released from their
carriage guides 120 by simply prying the pin 140 upward from
the sleeve 125 by means of a screwdriver or any other
suitable tool. The upward motion of the pin 140 overcomes
the spring force of the circlip 142 and drives the circlip
out of the groove 149 and into the space 144 so the pin can
be withdrawn from the sleeve 125. The easy removal and
replacement of the jig tools 19, 19' or 19" enables a
particular jig tool to be associated with any one of the
carriages 100 associated with any one of the slots 14.
The processor PC will determine at which of the slots
14 the apex 21 of the truss is to be located and will show
this either graphically, numerically or otherwise on a
display screen. If an apex tool 19' is not already
associated with the slot 14, the apex tool associated with
one of the other slots 14 can be removed by releasing the
pin 140 as described above and the apex tool snapped into
connection with the carriage 100 associated with the
appropriate slot 14. Similarly, other tools such as clamp
tool 19 " and pucks 19 can be released from particular
carriages 100 and connected to other carriages 100 under the
direction of the PC. The PC then controls the carriages 100
as described above to position the tools 19, 19' and 19" in
the required position for enabling the chords 20A-20C (and
web 20D in the embodiment shown in Figure 1) to be located
and fastened together by the connector plates previously
described.
Figures 11 to 14 show a further embodiment of the
invention in which a heel tool for locating the heel
position of a truss is shown. The heel tool 400 is not
movable along the channels 14 as is the case with the tools
19, 19', 19" previously described but is fixed in position
to the table 10 by pairs of holes 401 and 402 which are
provided on some or all of the sections 12A of the upper
platform 12. In the embodiment shown in Figure 11, two rows
(labeled C and D) of holes 401 and 402 are shown. The heel
tool 400 is fixed to one of the hole pairs 401 and 402 in
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row C on the section 12A' shown in Figure 11. The holes
401, 402 are covered by the tool 400 in Figure 11.
The tool 400 has a base section 403 and a heel point
section 405 which is moveable relative to the base section
403. As best shown in Figure 12 which shows the tool more
enlarged (and in a more retracted position than in Figure
11) the base 403 has a recess 431 in which is located a head
409 arranged on a pin 407, which pin is located in the hole
401 shown in Figure 11. The base 403 also carries an
elongate hole 415 which carries a floating pin 419 for
location in the hole 402 in the section 12A' shown in Figure
11. The pins 407 and 419, as well as the holes 401 and 402
are preferably configured similar to the pin 140 and sleeve
125 previously described for secure releasable connection.
The floating pin 419 in the elongated groove 415.provides
some degree of movement of the pins 407 and 419 relative to
one another to ensure that they can properly locate in the
precision drilled holes 401 and 402. The ability to locate
the tool 400 on the assembly table 20 and then simply move
the heel point section a short distance to define the heel
point location enables quick and accurate determination of
the heel point location and positioning the tool 400.
When the truss 20 is being formed, the PC will identify
the heel point location for the truss 20 which is to be
formed and will then display the holes 401 and 402 to which
the heel tool 400 should be attached. The PC will then
indicate the amount of movement of the heel point section
405 relative to the base 403 which is required in order to
position a heel point locating tab 412 on the tool 400 at
the desired point to identify the heel location of the truss
20. The section 405 carries a scale 411, and the base 403 a
pointer 447. Thus, the computer can indicate a value on the
scale 411 which should be aligned with the pointer 447 to
locate the heel point section 405 in the desired position
relative to the base 403 for positioning the heel point
locating tab 412 at the required place on the assembly table
400.
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As is best shown in the cross-sectional view of Figure
14, the heel point section 405 is formed from a generally C-
shaped channel having bottom wall 405A, end wall 405C and
top wall 405B. A pair of inwardly directing flanges 455 and
5 456 define a narrow slot 471 in the heel point section 405.
The base 403 is formed of a generally C-shaped channel
having a bottom wall 403A, a top wall 403B and end wall
403C. The walls 403A and 403B have free ends 472 which face
and generally abut the flanges 455 and 456. The walls 403A
10 and 403B define an open space 460 therebetween and the walls
405A and 405B define a cavity 470 therebetween.
A locking bar 449 is accommodated in the cavity 470 of
the heel point section 405 and has an enlarged head 450 and
a stem 456 which projects through the channel 471 between
15 the flanges 472. A bar 451 is coupled to the stem 456 and
projects into the space 460. Pin 407 carries an integral
eccentric 453. A sleeve 452 is provided about the eccentric
so that the pin and eccentric can rotate about the axis L of
the pin relative to the sleeve. The bar 451 is welded to the
sleeve 452 which holds the sleeve against rotation with the
eccentric 453.
In order to lock the heel point section 405 to the base
403 so that the heel point section cannot move relative to
the base 403, a handle 410 mounted on top of the pin 407 is
rotated in the direction of arrow F (Fig. 12) so the pin
rotates about its longitudinal axis L (Fig. 14) in hole 401.
This rotation causes the eccentric 453 to rotate with the
pin 407 and the rotation of the eccentric 453 causes the
sleeve 452 to move in the direction of arrow G in Figure 14
within the space 460 to pull the bar 451 and also the head
450 in the same direction so that the head securely clamps
the flanges 455 against the free ends 472 of the walls 403A
and 403B. Thus, the heel point section 405 is securely
clamped against the base 403 so it cannot move. In order to
release the heel point section 405 for movement relative to
the base 403 either direction of double headed arrow D in
Figure 12, the handle 410 is rotated in the opposite
CA 02368178 2001-09-26
WO 00/59695 PCT/US00/08153
16
direction to arrow F (back, for example, to the position
shown in Figure 12) so as to rotate the eccentric 453 to
move the sleeve 452 in a direction opposite arrow G in
Figure 14. This causes the clamping pressure supplied by
the head 450 which pushes the flanges 455 hard against the
free ends 472 to be released. The heel point section 405
can then slide in the direction of arrow D relative to both
the locking bar 449 and also the base 403 with the flanges
455 sliding on the free ends 472 of the walls 403A and 403B.
To prevent rotation of the heel point section 405 about bar
451, relative to the base 403 into and out of the plane of
the paper of Figure 12, which may be allowed by any
tolerance provided for the sleeve 452 and eccentric 453
within the space 460, a tongue 481 is provided on the heel
point section 405 which projects into the space 460 between
the walls 403A and 403B.
According to the preferred embodiment of the invention,
the jig system can be automatically set up to receive
components of a truss and the truss can be easily
manipulated to enable connector plates to be inserted in
place for formation of the truss. Thus, not only is set up
of the jig quickly effected, but formation of the truss is
also more easily and quickly performed.
Since modifications with the spirit and scope of the
invention may readily effected by persons of ordinary skill
in the art, it is to be understood that this invention is
not limited to the particular embodiment described by way of
example hereinabove.
