Improvements in and relating to Blades for Spiral Cutters.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in and relating to Blades for Spiral Cutters.
I, JOHN MULHERN, of 13, North Church Street, Lochee, in the County of Forfar,
Mechanic, do hereby declare the nature of this invention to be as follows:-
This invention relates to blades for spiral cutters of the type used in cropping
and cleaning the surfaces of textile fabrics, and in lawn mowers and the like; and
has for its object the construction of such blades so that they may be more quickly,
economically, and efficiently, sharpened than hitherto, and so that they shall be
less liable to fracture.
In spiral cutter blades as heretofore constructed, the cutting edge or face has
been formed of one relatively thin blade, and in the operation of sharpening these
together with their relative fixed blades, as heretofore conducted, considerable loss
of time and waste of material has resulted from the fact, that such form or con-
struction of spiral blade does not permit of the proper reception and retention of
the abrasive material used in sharpening. To obviate this, and in carrying out
my invention, I form the cutting edge or face of the spiral blade, of two or more
laminae or thicknesses of metal, wholly or partially separated by an intermediate
lamina or layer of relatively soft and absorbent material, such as lead, fibre, or
the like; which will readily receive and effectively retain the aforesaid abrasive
material. In the construction of such composite blades, I may adopt any form
of cross section for or relative disposition of, the outer or harder laminae, which are
suitable for receiving and retaining securely, the intermediate lamina of softer
material. Thus, in one form, I may first bend over or double the plate from
which the spiral blade is to be made, until it is transversely of, or nearly of, a
U section and again bend such resulting section through approximately a right
angle, until it becomes of an L shape, in which the horizontal limb is formed to
rest upon the core or shaft of the spiral cutter, and the vertical or normal limb con-
sists of the laminae beforementioned. In another form I may build up the com-
posite blades, of superimposed pieces of similar or nearly similar cross-section, such
as channel and L sections. In the case of channel and like sections, the composite
blades might be built in pairs. In either of the forms described the material of
the softer lamina, may be attached to the plate or plates before bending, or inserted
thereafter. In yet another form, I may construct the composite blade of two
L pieces, or sets of such, placed back to back, and holding the softer lamina
between their vertical limbs. In any of these or like forms, I may make the respective
laminae of the composite blade of relatively equal or unequal thickness as desired,
and I may secure them one to the other, or one or both of the harder laminae to
the softer lamina, by rivets or like form of fastening. In conjunction with the
composite blades as described, I may use a tool with a recessed cutting edge some-

page_text: what similar to a carpenter's grooving plane, for removing the abrasive material
after sharpening.
Dated this 14th day of May 1808
JOHN MULHERN,
Applicant.
Improvements in and relating to Blades for Spiral Cutters.
I, JOHN MULIERN, sometime of 13, North Church Street, Lochee, and now of
22, North Street, Dundee, in the County of Forfar, Mechanic, 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:-
This invention relates to blades for spiral cutters of the type used in cropping
and cleaning the surfaces of textile fabrics, and in lawn mowers and the like, and
has for its object the construction of such blades so that they may be more quickly,
economically, and efficiently sharpened than hitherto, and so that they shall be less
liable to fracture.
In order that my invention may be the better understood, I have hereunto
appended an explanatory sheet of drawings, in the several figures of which the
same reference numerals indicate the same or like parts where shown. Fig 1, is a
cross-section of a complete spiral cutter and its appurtenances, fitted with one
modification of my improvements.
Fig. 2, is an enlarged cross-section of the cutting edge of my improved blade.
Figs. 3, to 13, inclusive, show in cross-section, various modifications or forms of
construction of my improved blade.
Fig. 14, shows a tool for removing the abrasive material used in sharpening.
Arrows in connection with the figures show the direction of motion of the cutter
or its blades relative to the following description.
In spiral cutter blades as heretofore constructed, the cutting edge or face has
been formed of one relatively thin blade 22, and in the operation of sharpening
these together with their relative fixed blades 25, as heretofore conducted, con-
siderable loss of time and waste of material has resulted from the fact, that such
form or construction of spiral blade, does not permit of the proper reception and
retention of the abrasive material used in sharpening. To obviate this and in
carrying out my invention, I form the cutting edge or face of the spiral blade 21,
of two or more laminae or thicknesses of metal 22, and 23, wholly or partially
separated by an intermediate lamina or layer 24, of relatively soft material. Such
softer lamina may consist of lead, fibre, or like material, capable of readily receiving
into or upon its substance or surface, and there retaining, the emery powder or
other abrasive agent used in sharpening, and which has been applied thereto as
desired, either by sprinkling in the known way, or by previous incorporation with
such softer material.
In the construction of the composite blades before described, I may adopt any
form of cross-section for, or relative disposition of the outer or harder laminae, 22.
and 23, which may be suitable for receiving and retaining securely, the inter-
mediate lamina of softer material 24. In Fig. 3, I have shown a form of con-
struction or disposition suitable for converting the ordinary "bayonet
blade, into one of my improved composite blades. In Figs. 4, and 5, I illustrate
or single
the application of my invention to the relatively simple blades of some types of
lawn mowers, in which such blades are rivetted to arms 26, instead of being bedded
on a cylinder or core 27, as in Fig. 1. In Figs. 6, to 13, are shown various forms

page_text: or methods of constructing more complex blades, such as are used in the cropping
or cleaning of textile fabrics 28. Thus, in one form as shown by Figs. 6, 7, and 8,
I may first bend over or double the plate from which the spiral blade is to be made,
until it is transversely of, or nearly of a U section, Fig. 6, and again bend such
section through approximately a right angle, until it becomes of an L shape,
Fig. 8, in which the horizontal limb, 29, is formed to rest upon the core or shaft 27,
of the spiral cutter; and the vertical or normal limb 30, consists of the laminae 22,
and 23, formed to receive the intermediate lamina 24, Fig. 7 Figs. 9, and 10, are
modifications of this form designed to resemble the "bayonet" shape, Fig. 3,-
Fig. 10, showing the complete blade ready for the intermediate lamina, and Fig. 9,
the same in the process of evolution from the U-section, Fig. 6.
In another form as illustrated more particularly by Figs. 11, and 12, I may
build up the composite blades 21, of superimposed pieces of similar or nearly
similar cross-section 31, and 32; such as the channel section, Fig. 11, and the
L section, Fig. 12. In the case of such sections, the composite blades may be
built or shaped in pairs,--that is to say the superimposed blades may be bent
together into the superimposed sections 31, and 32, and in such case, as also in
those of Figs. 6, to 10, the material of the softer lamina, where its character per-
mits, may be attached to the plate or plates before bending, or it may be inserted
thereafter, as convenient or desirable.
In any of the foregoing or like forms, I may make the respective laminae 22,
23, and 24, of the composite blade 21, of relatively equal or unequal thickness
as desired. By my improved form of construction however, it will be obvious that
the cutting blades, being better supported, may be made much thinner than
heretofore without risk of fracture, and it will also be obvious that in such forms
as those illustrated by Figs. 3, and 5, only the leading blade, 22, need be made of
metal capable of taking a cutting edge, while in the other forms, only such lead-
ing portions need be fitted to receive such edge.
Where the form of construction renders it necessary, I may secure the laminao
the one to the other, or the harder laminae to the softer, by rivets 35, or like known
form of fastening.
In conjunction with my composite blades 21, and where for any reason it may be
desirable, I may use a tool or blade 36, with a recessed cutting edge 37, for remov-
ing the abrasive material from the cutting face or edge after sharpening.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I wish it to be clearly under-
stood that although I have for purposes of illustration, described and shown such
invention in connection with various particular forms of composite blade, and as
with two harder laminae containing one intermediate or softer lamina, I do not
limit myself to such forms of applying my said invention, or to the said specific
number of laminae, but that I hold myself free to apply my invention in such form
and in connection with such a number of laminae, as shall conform with the spirit
and scope of my said invention; and I declare that what I claim is ; —
(1) In blades for spiral cutters, the combination, or use in conjunction with
the cutting blade, of a suitably held and supported blade or lamina of softer
material, distinct from but contiguous to such cutting blade; for the purposes
herein set forth, and substantially as hereinbefore described and illustrated in the
appended sheet of drawings.
(2). In blades for spiral cutters, the combination and arrangement of parts
forming a composite blade, and consisting essentially of two or more laminae of
relatively hard material wholly or partially separated the one from the other by
an intermediate lamina, or intermediate laminae, of a softer material, capable of
receiving and retaining an abrasive agent; for the purposes herein set forth, and
substantially as hereinbefore described and illustrated in the appended sheet of
drawings.

page_text: (3) In blades for spiral cutters, the methods of arranging, forming, or dis-
posing the containing or harder laminae so as to suitably receive and support the
contained or softer lamina or laminae, and thus to form together a composite blade,
suitable for attachment to a shaft or core, substantially as hereinbefore described
and illustrated in the appended sheet of drawings.
1441 Jahon 1900