Year: 1886

page_text: Date of Application, 9th Nov, 1886;
Complete Left, 9th Aug., 1887;
Complete Accepted 9th Sept., 1887
RESERVI
We HENRY FOSTER and ALFRED FOSTER, both of Boxmoor Saw Mills, Hemel
Hempstead in the County of Herts, Timber Merchants and Manufacturers, do hereby
declare the nature of this invention to be as follows:-
In band saw frames, as at present constructed, the travel of the saw is effected
through one or other of the tension pulleys around which the saw band passes, the
strain on the band being such as will ensure its efficient action on the work. This
strain, in all cases great, is excessive when the breadth of the saw is increased to, say,
four or more inches, and the consequence is the frequent snapping of the bands at
some point in their passage over or between the pulleys.
To remove, or greatly to decrease this liability of fracture, is the main object of the
present invention.
To this end, we arrange, both above and below the work table or travelling carriage,
a pair of gripping rolls, which bite the band saw immediately above and below the
level of the work. To one or both of the rolls, below the table or carriage, we apply
driving power for imparting motion to the band saw. One of each pair of rolls is
formed with a flange, which serves as a support for the back of the band saw.
The power of traction of the lower pair of rolls is increased or diminished by means
of a screw acting upon the spindle of one or both of them, and the tension on the saw,
caused by the resistance of the upper pair of rolls, may be modified or intensified to
suit the nature of the work in hand, by the similar adjustment of a screw acting upon
the spindles on which they revolve. If necessary, a brake may also be applied to these
rolls to increase their resistance to the downward pull of the lower pair of rolls.
The tension that is put on the saw blade by the two pairs of gripping rolls, is in the
line of cut of the saw, and thus the strain on the metal is in the direction in which it can
best sustain it. The band saw may run comparatively slack upon its carrying pulleys,
which will now no longer act as tension pulleys, or put any strain upon the band.
We propose also to do away with the fixed guides used to steady the saw teeth while
cutting, as the gripping rolls, which will be made adjustable to suit the work in hand,
will prevent all lateral vibration of the band saw.
1000

page_text: Improvements in the Construction of Band Saw Frames.
We, HENRY FOSTER and ALFRED FOSTER, both of Boxmoor Saw Mills, Hemel
Hempstead, in the County of Herts, Timber Merchants and Manufacturers, do hereby
declare the nature of this invention and in what manner the same is to be performed
to be particularly described and ascertained in and by the following statement :-
Our invention relates to band-saw frames :-
In band-saw frames as heretofore constructed motion is communicated to the saw
through the medium of one or other of the tension pulleys around which the saw-band
passes, the strain on the band being such as will ensure its efficient action. This
strain, in all cases great, is excessive when using saw-bands of say four or more inches
in breadth, the consequence being that the bands frequently snap, especially in their
passage over the pulleys.
The object of our invention is to reduce this liability to fracture to a minimum and
to this end it consists essentially in arranging both above and below the work table or
travelling carriage, rolls which grip or bite the band saw above and below the level
of the work, motion being communicated to one or both of the rolls below the table or
carriage, for imparting motion to the band-saw.
The accompanying drawing shews in side elevation so much of a band-saw frame as
is necessary to illustrate our invention.
a, is the frame of the machine and b, b, are the tension pulleys around which the
saw-band passes. c, is the work table which as shewn is operated by the racks and
pinions d, d, the worm and worm wheel e, and the bevel wheels f, on the shaft of the
tension pulley b¹. It will be obvious however that the improvements hereinafter
described are equally applicable to a machine in which the work-table is stationary.
9, 9', and h, h, are the two pairs of rollers between which the band passes. Motion
is communicated to one or both of the rollers h, h¹, and is transmitted to the band
owing to the grip of the said rollers upon the band. As shewn in the drawing motion
is communicated to the roller h, through the medium of the belt i.
The power of traction of the rolls h, h¹, upon the band is increased or diminished
by means of a screw k, acting upon the spindle of one or both of them. The
rollers 9, 9', preferably offer a certain amount of resistance to their rotation, in order
to produce tension upon the saw. This resistance may be modified or intensified to
suit the nature of the work in hand by the adjustment of a screw 1, acting upon the
spindles on which the rollers g, g', revolve., If necessary a brake may also be applied
to the rolls g, g', to increase their resistance to the downward pull of the lower pair of
rolls or they may be positively driven by any suitable means at a slightly lower rate of
speed than the rollers h, h².
The tension that is. put on the saw-blade by the two pairs of gripping rolls is in
the line of cut of the saw and thus the strain on the metal is in the direction in which
it can best sustain it.

page_text: The saw-band may be comparatively slack upon the pulleys 6, 6', which, with the
improved arrangement will serve only as guide pulleys without putting strain upon
the band.
One of each pair of rollers g, g, h, h¹, is provided with a flange in order to retain
the band in position between the same against the pressure of the work when in
operation; the guide rolls or blocks heretofore used are thus rendered unnecessary.
The gripping rolls 9, 9', are preferably made adjustable in a vertical direction
relatively to the rolls h, ², to suit different kinds of work and to prevent all lateral
vibration of the band-saw.
Although we have only shewn our invention as applied to a band-saw frame in
which the saw passes around two pulleys placed vertically one above the other it is
obvious that it may be applied with equal advantage to a saw frame in which the saw
passes around three or more pulleys or in which the bands are arranged horizontally
instead of vertically.
Having now particularly described and ascertained the nature of our said invention
and in what manner the same is to be performed we declare that what we claim is :-
1. The combination with a band-saw, of pulleys or rollers arranged to grip the
straight portion of the saw between the guide pulleys and to impart motion to the said
saw, substantially as described.
2. The combination with a band saw of two pairs of pulleys or rollers arranged to
grip the saw above and below the work table and to maintain the tension of that
portion of the said saw which is in operation, one pair of the said rollers serving to
impart motion to the band while the other pair offers a certain resistance to the
motion thereof, all substantially as described with reference to the accompanying
drawing.
Dh: th A 1007