Roof pin

A roof pin particularly adapted for mine or tunnel roof support in which the strata-gripping assembly has a plurality of locking discs mounted on and carried by one end of an elongate rod, the locking discs being resilient and having a periphery adapted to engage the strata defining the roof pin hole. Spacers are mounted on and carried by the rod end, and are located between and engage each axially adjacent pair of locking discs, the spacers having a periphery located radially inward of the locking disc periphery. A retainer on the rod at opposite ends of the strata-gripping assembly holds the discs and spacers on the rod end. The locking discs have downturned peripheries adapted to engage the roof strata and flex resiliently downwardly and inwardly upon insertion of the pin, and expand upwardly and outwardly upon application of a load force on the pin during roof support. The spacers engage a subjacent locking disc radially inward of the subjacent disc periphery for reinforcing the subjacent disc and permitting the expansion of the disc periphery, and engage a superjacent locking disc radially inward of the superjacent disc periphery for permitting downward flexing of the disc periphery. The spacers include a bearing member that engages the subjacent locking disc, and at least one spacing member that engages the bearing member and the superjacent locking disc, the number of spacing members determining the axial spacing between the locking discs.

BACKGROUND OF THE INVENTION 
This invention relates generally to improvements in a roof pin used for 
mine or tunnel roof support, and more particularly to an improved pin 
assembly that effectively grips the roof strata under support load upon 
insertion into a compatible pin hole. 
The majority of the heretofore conventional types of pins utilize an 
expansion shell for gripping the roof strata. When utilizing this type of 
roof pin, the roof pin and expansion shell are inserted into a drilled 
hole in the roof strata to the desired depth. When fully inserted, the 
pin, which is in fact a bolt, is turned to expand the expansion shell 
blades outwardly into gripping relation with the roof strata. With this 
particular roof pin, the expansion shell must be maintained in the 
location desired while at the same time the shell blades must be manually 
expanded. 
SUMMARY OF THE INVENTION 
The present roof pin is inserted into a drilled hole in the roof strata. 
The structural arrangement and provision of the locking members on the 
roof pin enable the locking members to frictionally engage the sides of 
the pin hole so as to be maintained at any position during insertion, and 
when fully inserted to the desired depth, the locking members will 
automatically expand and grip the roof strata upon application of support 
load. 
The present roof pin includes a strata-gripping assembly having a plurality 
of locking discs mounted on and carried by one end of an elongate rod, the 
resilient disc being resilient and having a periphery adapted to engage 
the roof strata defining the pin hole, and having spacer means mounted on 
and carried by the pin end and located between and engaging each axially 
adjacent pair of locking discs, the spacer means having a periphery 
located radially inward of the locking disc periphery. Retaining means on 
the rod at opposite axial ends of the strata-gripping assembly hold the 
discs and spacer means on the rod. 
The resilient locking discs have downturned peripheries adapted to engage 
the strata and to flex resiliently downwardly and inwardly upon insertion 
of the pin, and to expand upwardly and outwardly upon application of 
support load on the pin. 
The spacer means engages a subjacent locking disc radially inward of the 
subjacent disc periphery for reinforcing the subjacent disc and for 
permitting the expansion of the disc periphery, and engages a superjacent 
locking disc radially inward of the superjacent disc periphery for 
permitting downward flexing of the disc periphery. 
The spacer means includes a bearing member that engages the subjacent 
locking disc, and at least one spacing member that engages the bearing 
member and the superjacent locking disc, the number of spacing members 
determining the axial spacing between adjacent locking discs. 
In one embodiment, each axially successive superjacent locking disc on the 
rod has a greater peripheral dimension than the next axially subjacent 
locking disc, whereby each successive superjacent locking disc can move 
further radially outward than the next subjacent locking disc. 
In another embodiment, a plurality of locking members are mounted on the 
elongate rod, each locking member having a radially extending resilient 
portion. The locking members are located in adjacent superimposed relation 
on the pin end with the radially extending resilient portions being 
located in various angular positions about the pin axis to provide a 
substantially circular envelope periphery engageable with the roof strata. 
In one species, the locking member has a single radially extending 
resilient portion, and in another species, the locking member has a pair 
of opposed, radially extending resilient portions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to the roof pin generally indicated by 10 in FIGS. 1 and 2, it 
will be understood that the roof pin 10 includes an elongate rod 11 having 
a strata-gripping assembly indicated by 12 attached to one end 13 of rod 
11. The strata-gripping assembly 12 is held by retaining means consisting 
of an upset rod shoulder 14 and a cold-headed rod end 15. 
The strata-gripping assembly includes a plurality of resilient locking 
discs 16, constituting locking members, made of spring steel, and having 
either a continuous or interrupted periphery 17. Each locking disc 16 has 
a center aperture 20 so as to enable the disc 16 to be slip-fitted over 
the rod end 13. The periphery 17 of the locking disc 16 is downturned to 
engage the roof strata and flex resiliently downwardly and inwardly upon 
insertion of the roof pin and to expand upwardly and outwardly upon 
application of support load. 
Spacer means referred to by 21 are mounted on and carried by the rod end 
13, and are located between and engage each axially adjacent pair of 
locking discs 16, the spacer means 21 having a periphery located radially 
inward of the locking disc periphery 17. More particularly, the spacer 
means 21 engages a subjacent locking disc 16 radially inward of the 
subjacent disc periphery 17 for reinforcing the subjacent disc 16 and for 
permitting expansion of the subjacent disc periphery 17, and engages a 
superjacent locking disc 16 radially inward of the superjacent disc 
periphery 17 for permitting downward flexing of the superjacent disc 
periphery 17. 
More particularly, the spacer means 21 includes a bearing member 22 that 
engages the subjacent locking disc 16, and at least one spacing member 23 
that engages the bearing member 22 and the superjacent locking disc 16, 
the number of spacing members 23 determining the axial spacing between 
adjacent locking discs 16. The bearing member 22 and spacing member 23 are 
also slip-fitted on the rod end 13. In FIG. 1, a pair of spacing washers 
24 are slip-fitted on the rod end 13 and bear against the retaining 
shoulder 14 and the first locking disc 16. 
To assemble the strata-gripping assembly, the spacing washers 24 are first 
slipped on the rod end 13 to engage the retaining shoulder 14, and then 
the locking discs 16 are slipped on the rod end 13 with the appropriate 
bearing member 22 and spacing member 23 located between axially adjacent 
locking discs 16. The pin end 15 is then cold-rolled to secure the 
strata-gripping assembly. 
To utilize this roof pin 10, an appropriate pin hole 25 is drilled in the 
roof to the desired depth. Then, the roof pin 10 is inserted into the pin 
hole 25, the downturned peripheries 17 of the locking discs 16 engaging 
the strata and flexing downwardly and inwardly until the strata-gripping 
assembly 12 is located at the desired depth in the pin hole 25. The 
locking disc peripheries 17 are resiliently flexed outwardly into gripping 
engagement with the strata, and upon application of a support load on the 
roof pin 10, the locking disc peripheries 17 dig deeper into the roof 
strata and expand upwardly and outwardly into even more effective gripping 
relation with the strata. 
In the embodiment of FIGS. 3-5, the roof pin 10a has a threaded rod end 
26a. The locking discs 16a are slip-fitted over the rod end 26a. However, 
the spacer means 21a is of a unitary construction consisting of a nut 27 
that is threadedly attached to the rod end 26a between axially adjacent 
locking discs 16a. Instead of cold-rolling the rod end as in the 
embodiment of FIG. 1, a lock nut 30 is threadedly attached to the rod end 
26a and serves to hold the strata-gripping assembly 12a on the roof pin 
end 26a. 
The strata-gripping assembly 12a of FIGS. 3-5 is assembled substantially in 
the same manner as described with respect to the embodiment of FIG. 1 
except that the spacer means 21 and the end lock nut 30 are threadedly 
attached to the rod end 26a. The purpose and function of the spacer means 
21a of FIGS. 3-5 are the same as the spacer means 21 of the embodiment of 
FIG. 1. Moreover, the installation of the roof pin and the functional 
purpose and cooperation of the locking discs 16a and spacer means 21a of 
the embodiment of FIGS. 3-5 are the same as that previously described with 
respect to the embodiment of FIG. 1. 
In the embodiment of FIGS. 6-7, the roof pin 10 is provided with an upset 
shoulder 14b and a cold-headed rod end 15b constituting a retaining means 
for the strata-gripping assembly 12b. 
Each axially successive superjacent locking disc 16b on the rod end 26b has 
a greater peripheral dimension than the next axially subjacent locking 
disc 16b, whereby each successive superjacent locking disc 16b can move 
further radially outward than the next subjacent locking disc 16b upon 
application of a support load to the roof pin 10b in the event of any 
tendency for the roof pin 10b to move outwardly of its hole, the locking 
discs 16b would expand upwardly and outwardly into undisturbed strata for 
effective gripping action. 
The spacer means 21b can consist of unitary members or separate bearing 
members and spacing members as in FIG. 1. The purpose of the spacer means 
21b is the same as that previously described with respect to the 
embodiment of FIG. 1. 
In the embodiment of FIGS. 8-10, the roof pin 10c includes a threaded rod 
end 26c, and a retaining shoulder 14c and a lock nut 31 constituting 
retaining means for securing the strata-gripping assembly 12c. The 
strata-gripping assembly 12c includes a plurality of locking members 32 
slip-fitted on the rod end 26c, each with a radially extending resilient 
portion 33. More particularly, locking members 32 are located in 
superimposed relation with the radially extending resilient portions being 
located in various angular positions about the pin axis to provide a 
substantially circular envelope periphery engageable with the strata 
defining the pin hole. 
The radially extending resilient portions 33 are downturned and adapted to 
engage the roof strata and flex resiliently downwardly and inwardly upon 
insertion of the pin, and to expand upwardly and outwardly upon 
application of support load, similar to the action and function of the 
peripheries 17 of the locking disc 16 in the embodiment of FIG. 1. 
FIG. 11 discloses a modification of the locking element 33 that can be 
utilized in the embodiment of FIG. 8. This locking member 33 has a pair of 
opposed, radially extending resilient portions. It can be used in lieu of 
or in combination with the locking members 32 of the embodiment of FIG. 8. 
The purpose and function of the radially extending resilient portions 34 
are the same as the resilient portions 33 of locking member 32.