U.S. patent application number 09/783685 was filed with the patent office on 2002-08-22 for link for sharp chain conveyor.
Invention is credited to Roberson, Russell K..
Application Number | 20020112941 09/783685 |
Document ID | / |
Family ID | 25130103 |
Filed Date | 2002-08-22 |
United States Patent
Application |
20020112941 |
Kind Code |
A1 |
Roberson, Russell K. |
August 22, 2002 |
Link for sharp chain conveyor
Abstract
A spiked H-style link for a sharp chain conveyor where the
single centrally-placed saddle of the prior art is replaced by a
double saddle with a centrally-located opening shaped to receive a
sprocket tooth. The double saddle moves each saddle outward from
the central portion of the spiked link to enhance the rigidity of
the legs between which the connecting pins act. The legs are
provided with a thickened offset step on the lower inner portion of
each leg. There is a corresponding decrease in the thickness of the
legs in the region where the connecting link works. By decreasing
the thickness of the legs in the region outside the offset step,
the connecting link may be widened, allowing for a greater bearing
surface on the connecting pin and thus reducing the rate of wear on
the connecting pin.
Inventors: |
Roberson, Russell K.;
(Russellville, AR) |
Correspondence
Address: |
Ray F. Cox, Jr.
Wright, Lindsey & Jennings LLP
Suite 2200
200 West Capitol Avenue
Little Rock
AR
72201
US
|
Family ID: |
25130103 |
Appl. No.: |
09/783685 |
Filed: |
February 14, 2001 |
Current U.S.
Class: |
198/851 |
Current CPC
Class: |
B65G 2201/02 20130101;
B65G 17/40 20130101; B27B 31/006 20130101 |
Class at
Publication: |
198/851 |
International
Class: |
B65G 017/06 |
Claims
What is claimed is:
1. In a conveyor chain for transporting logs along the length of a
chain raceway, the conveyor chain comprising an endless loop of
interconnected links traversing a path defined between at least one
infeed sprocket gear and at least one outfeed sprocket gear, the
sprocket gears having at least one tooth for engaging the links,
the links comprising alternating spiked links and connecting links
connected by connecting pins, the improvement comprising: a spiked
link comprising a pair of legs having downwardly-facing surfaces
for bearing against said raceway, a centrally-disposed opening for
receiving a sprocket tooth, a forwardly-disposed saddle disposed
between said centrally disposed opening and a forward portion of
said pair of legs, and a rearwardly-disposed saddle disposed
between said centrally-disposed opening and a rearward portion of
said pair of legs.
2. The improvement of claim 1 wherein said spiked link further
comprises a first region of each of said pair of legs and a second
region of each of said pair of legs, said first region having a
first thickness and said second region having a second thickness,
such that together said first thickness and said second thickness
define an offset step in an inner side of each of said pair of
legs.
3. The improvement of claim 2 wherein said first regions comprise
those portions of said pair of legs between which an adjacent
connecting link works while said chain is traversing said path.
4. The improvement of claim 3 wherein said first thicknesses are
less than said second thicknesses.
5. The improvement of claim 4 wherein a connecting link is disposed
between said first regions and further wherein said connecting link
is characterized by a connecting link width greater than an offset
width defined between said second regions.
6. A spiked link for a conveyor chain for transporting logs along
the length of a chain raceway, the conveyor chain comprising an
endless loop of interconnected links traversing a path defined
between at least one infeed sprocket gear and at least one outfeed
sprocket gear, the sprocket gears having at least one tooth for
engaging the links, the links comprising alternating spiked links
and connecting links connected by connecting pins, comprising: a
pair of legs having downwardly-facing surfaces for bearing against
said raceway, a centrally-disposed opening for receiving a sprocket
tooth, a forwardly-disposed saddle disposed between said centrally
disposed opening and a forward portion of said pair of legs, and a
rearwardly-disposed saddle disposed between said centrally-disposed
opening and a rearward portion of said pair of legs.
7. The spiked link of claim 6 further comprising a first region of
each of said pair of legs and a second region of each of said pair
of legs, said first region having a first thickness and said second
region having a second thickness, such that together said first
thickness and said second thickness define an offset step in an
inner side of each of said pair of legs.
8. The spiked link of claim 7 wherein said first regions comprise
those portions of said pair of legs between which an adjacent
connecting link works while said chain is traversing said path.
9. The spiked link of claim 8 wherein said first thicknesses are
less than said second thicknesses.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The present invention relates to the links in an infeed
conveyor for conveying logs into a saw in a sawmill, and in
particular, to the links in a type of conveyor known as a sharp
chain.
[0005] 2. Brief Description of the Related Art
[0006] A conveyor known as a sharp chain is employed in sawmills to
convey and feed logs into a saw. The sharp chain is typically a
link-type chain in which alternating links have upstanding spikes
for engaging the log and maintaining it in a fixed orientation.
These links, referred to as spiked links or dog links, are
connected by pins to connecting links. The whole forms an endless
chain which is sprocket-driven. The endless chain passes around at
least one infeed sprocket gear and at least one outfeed sprocket
gear.
[0007] Examples of sharp chains are disclosed in U.S. Pat. Nos.
4,881,584; 5,765,617; 6,062,281; and 5,385,186.
[0008] An early form of spiked link for a sharp chain is disclosed
in U.S. Pat. No. 4,886,156 to Records et al. In this style of sharp
chain, the spiked link has a single leg which rides in a V-shaped
guide. Lateral stability can be a problem with this type of link,
which has been mostly supplanted by an H-style link. The H-style
link has two legs connected by a centrally-located saddle. The
H-style link improves the lateral stability of the sharp chain.
Sharp chains incorporating the H-style link typically are driven by
sprocket gears with teeth that bear against the ends of the
connecting links or against the saddle. In the commonest form of
spiked link, the sprocket teeth bear against the ends of the
connecting links, which therefore puts considerable pressure on the
pins that connect the connecting links to the spiked links. Since
the pins have limited bearing area and are further subject to wear
from rotational motion of the links as they pass around the
sprocket gears, failures to the pins and the ends of the connecting
links are a common problem.
[0009] An additional problem with the H-style spiked link is that
the legs on either side of the saddle tend to exhibit excessive
flexibility as a result of the central placement of the saddle and
the limited rigidity that the relatively small saddle imparts to
the spiked link. Such flexibility is undesirable in that the
flexing of the legs contributes to wear and consequent failure of
the connecting pins and connecting links.
[0010] The limitations of the prior art are overcome by the present
invention as described below.
BRIEF SUMMARY OF THE INVENTION
[0011] The present invention is directed to an improvement in the
design of a spiked link for a sharp chain conveyor. The spiked link
of the present invention departs from the prior H-style design in
that the single centrally-placed saddle is replaced by a double
saddle with a centrally-located opening shaped to receive a
sprocket tooth. The resulting center drive action for the spiked
link avoids driving the chain from the ends of the connecting links
and thus removes this source of failure for the connecting pins and
connecting links.
[0012] Furthermore, the double saddle design moves each of the two
saddles outward from the central portion of the spiked link. The
distance between each saddle and the connecting pin is therefore
reduced. This contributes to the rigidity of the legs between which
the connecting pins act. With less flexion of the legs, the
potential for the connecting pins to bind and wear is reduced.
[0013] A second feature of the present invention is that the legs
are provided with an offset step on the inner portion of each leg.
The offset step is defined by the portion of the legs where the
connecting link never "works" during any portion of the chain's
motion around the circuit of the sprocket gears. Since the
connecting link never intrudes into this space, the offset step
allows the legs in these areas to be thickened. This allows a
corresponding decrease in the thickness of the legs in the region
where the connecting link works. Since the width of the spiked link
is fixed by the conventional size of sharp chains commonly employed
in the industry, the thickness of the legs can only be decreased on
the inner sides. By decreasing the thickness of the legs in the
region where the connecting link works, the connecting link may be
widened from the prior art connecting link. Significantly, this
allows for a greater bearing surface on the connecting pin and thus
reduces the rate of wear on the connecting pin and on the ends of
the connecting links. By combining the thickened area of the offset
steps and reducing the longitudinal distances of the legs between
the saddles and the connecting pins, the legs retain sufficient
stiffness and strength so that no problems are introduced by
reducing the thickness of a portion of the legs to increase the
bearing surface of the connecting pins.
[0014] It is therefore an object of the present invention to
provide for an improved spiked link for a sharp chain conveyor in
which the central saddle is replaced by a double saddle.
[0015] It is a further object of the present invention to provide
for such an improved spiked link having an offset step allowing an
increased width for the connecting link and a consequently greater
bearing area for the connecting pin.
[0016] These and other features, objects and advantages of the
present invention will become better understood from a
consideration of the following detailed description of the
preferred embodiments and appended claims in conjunction with the
drawings as described following:
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0017] FIG. 1 is a perspective view of a portion of a prior art
sharp chain showing the prior art single saddle spiked link and
prior art narrow connecting link.
[0018] FIG. 2 is a partially exploded perspective view of the sharp
chain of the present invention showing the double saddle spiked
link and the widened connecting link.
[0019] FIG. 3 is a side elevation view of a sharp chain conveyor
with sprocket gears for driving the endless sharp chain.
[0020] FIG. 4 is a cross-section elevation view of the spiked link
and connecting link of FIG. 2 taken along the line 4-4.
[0021] FIG. 5 is a top plan view of the spiked link and connecting
link of FIG. 4.
[0022] FIG. 6 is a rear elevation view of the spiked link and
connecting link of FIG. 5.
[0023] FIG. 7 is a cross-section front elevation view of the spiked
link of FIG. 4 taken along the line 7-7.
DETAILED DESCRIPTION OF THE INVENTION
[0024] With reference to FIGS. 1-7, the preferred embodiment of the
present invention may be described as follows.
[0025] FIG. 3 shows a typical conveyor for transporting a log 10
utilizing an endless sharp chain 11. The sharp chain 11 comprises
alternating spiked links 12 and connecting links 13. The spiked
links 12 have one or more upstanding spikes 20. The endless sharp
chain 11 passes along a raceway 14 on which downwardly facing
surfaces of the spiked links 12 bear. The raceway 14 lies between
an infeed sprocket gear 15 and outfeed sprocket gear 16. Other
sprocket gears 17 may also be employed to define the path around
which the endless sharp chain 11 passes or to drive the sharp chain
11 or both. Each sprocket gear 15, 16, 17 comprises a plurality of
sprocket gear teeth 18 which engage the sharp chain 11. A power
source, for example a motor 19, drives one or more of the sprocket
gears 15, 16, 17 to move the sharp chain 11. In operation, the log
10 is placed upon the upper surface of the sharp chain 11 where the
log 10 is engaged by the spikes 20 on the spiked links 12. The log
10 is thus transported along the length of the raceway 14 between
the infeed sprocket gear 15 and the outfeed sprocket gear 16 while
the weight of the log 10 is transmitted through the sharp chain 11
to the supporting raceway 14.
[0026] The prior art sharp chain is described with reference to
FIG. 1. The prior art sharp chain comprises alternating
single-saddle spiked links 30 and narrow connecting links 31. The
prior art spiked link 30 comprises a pair of legs 32, each of which
has an upstanding spike 33. The legs 32 are connected by a single
centrally-located saddle 34. The spiked links 30 are connected to
the connecting links 31 by connecting pins 35. The connecting links
31 are free to rotate about the pins 35 so that the endless sharp
chain is able to flex as it passes around its path on the conveyor
as defined by the sprocket gears 15, 16, 17. In order to drive the
prior art sharp chain, each tooth 18 of the sprocket gear is set to
bear against the end of a respective connecting link 31. This
produces considerable stress on the end of the connecting link 31
and the pin 35.
[0027] The improved sharp chain and spiked link of the present
invention are described with reference to FIGS. 2 and 4-7. The
sharp chain comprises alternating spiked links 40 and connecting
links 50 connected by connecting pins 51, around which the
connecting link 50 is free to rotate. The improved spiked link 40
comprises a pair of legs 41, each having an upstanding spike 42 and
downwardly facing surfaces 45 to bear against the raceway 14.
Rather than the single centrally-placed saddle 34 of the prior art,
the spiked link 40 has two saddles 43 connecting the legs 41. The
space between the two saddles 43 defines an opening 44 for
receiving a sprocket gear tooth (not shown). The sharp chain of the
present invention is therefore driven by the pressure of the
sprocket gear tooth against one or both of the saddles 43 rather
than against the end of the connecting link 50. Further, the
saddles 43 are placed outwardly from the center of the spiked link
40. The distance between each saddle 43 and the connecting pin 51
is therefore reduced. This contributes to the rigidity of the legs
41 between which the connecting pin 51 is placed. With less flexion
of the legs 41, the potential for the connecting pin 51 to bind and
wear is reduced.
[0028] The legs 41 are provided with an offset step 60 on the inner
side of each leg 41. The offset step 60 is defined by a first
region 61 of the inner side of the legs 41 where the connecting
link 50 "works" by rotating upwardly and downwardly during the
sharp chain's motion around the circuit of the sprocket gears.
Since the connecting link 50 never intrudes outside this first
region 61 of the inner side of the legs 41, the offset step 60
allows the legs 41 to be thickened in a remaining second region 62.
This allows a corresponding decrease in the thickness of the legs
41 in the first region 61 where the connecting link 50 works. Since
the width of the spiked link 40 is fixed by the conventional size
of sharp chains commonly employed in the industry, the thickness of
the legs 41 can only be decreased on the inner sides. By decreasing
the thickness of the legs 41 in the first region 61 where the
connecting link 51 works, the connecting link 50 may be widened
from the prior art connecting link 31. Significantly, this allows
for a greater bearing surface on the connecting pin 51 and thus
reduces the rate of wear on the connecting pin 51 and on the ends
of the connecting links 50. By combining the thickened area of the
second region 62 and reducing the longitudinal distances of the
legs 41 between the saddles 43 and the connecting pins 51, the legs
41 retain sufficient stiffness and strength so that no problems are
introduced by reducing the thickness of the first region 61 of the
legs 41 to increase the bearing surface of the connecting pins
51.
[0029] The present invention has been described with reference to
certain preferred and alternative embodiments that are intended to
be exemplary only and not limiting to the full scope of the present
invention as set forth in the appended claims.
* * * * *