Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The pre3ent invention concerns a device for removiny
the wearing surface of a ~ire, comprising a tire fixing memberr
which rotates the tire if need be, and a rotating cutting member
shaped like a disk and on the circumference of which cutting
bits have been affixed.
Devices of ~his kind are used for removing the wearing
surface of vehicle tires meant to be resurfaced, the new wearing
surface being affixed with the aid of a cement in place of the
wearing surface that has been removed~ A device of this kind
is known in prior art e.g. through the Garman publicizing print
No. 2,429,145. In said device, in depressions on the periphery
of a disk disk-shaped cutting bits have been affixed with the aid
of wedge pieces that can be tightened with the aid of screws.
~his device of prior art is encumbered by the following drawbacks.
It features poor arrangements for disposal of the chips that are
removed. ~his is associated with a great elevation of temperature,
with consequent risk of blocking as the overheated rubber material
tends to become vulcanized to adhere to the depression in front of
the cuttîng bit~ Servicing of the device is slow work because
of the inconvenient dismounting and replacing of bits, and in
addition it is not possible in this device to adjust ~he position
of the bits, that is their cutting angle. The cut is completely
smooth, although professionals usually believe that the wearing
surface will stick better to a rough surface. It has furthermore
been suggested that the device should be used in a direction
longitudinal to the wearing surace of the tire, whereby grQoveS
paralleliny the periphery of the tire are produced in the surface
upon which the new surface
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will be fixed. These grooves inter~ere with the degassing that
has to be carrled ou-t in co~nect.ion with the affixing of the new
surface. Gas inclusions entrained under the surfacing usually
cause premature loosening of the surface.
The object of the present invention is to afford an
improved device of the t~pe mentioned, by the aid of which the
wearing surface of a tire can be removed with high speed, with
low energy consumption and wi~hout detriment from heating.
Broadl~ speaking, the present invention provides
a device for removing the wearing surface of a tire, which
comprises a disk-shaped cutting member formed of two disks
detachably joined to each other, the disks having means defining
a groove around the periphery of the cutting member and including
a number of tire surface cuttiny bits disposed in the cutting
member groove in spaced reIationship around the member and being
held in the cutting member groove. by clamping action when the
two disks are joined together; the GUtting bits each being
formed of at least a partial ring having sharp cutting edges, the
bits being held in the cutting member groove with portions of
the cutting edges exposed, the exposed cutting edges being
adapted to cut tire wearing surfaces upon engagement with a tire
rotated relative to the deuice, the rings including means defining
periphexal groo~es thereabout, the device ~urther includîng bit
retaining strips fastened to. the cutting member and passing
around the bits in the bit grooves for additionally retaining
the ~its in the cutting member periphery gxoove.
The cutting edges of t~e ring-shaped cutt.ing bits perfor~
a slicing cut, whereby the wearing surface is cut away in rather
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larye pieces, which can depart through the central hole of the
ring. The material that is bein~ cut is not subjected to any
powerful abrasion nor deformations resulting ~rom pressure, ~here-
by there is no substantial heating. It is ~urther notPd that the
air flow has good access through the cutting ring to cool the work.
In a favourable embodiment of ~he invention the
cutting member consists of two disks intended to be ~ixed to each
other, whereby the cutting bits will be held b~ form fit in the
groove on the periphery face of the disks. Hereby, ~hen the bits
have become dull, all the bits may be rapidly and with ease exchanged
for new ones, or the rings may be rotated, whereby the dulled bit
moves into the fixing groove and from the fixing groove a new
sharp edge emerges.
The invention is more closely described in the
following with reference to the attached drawing, wherein:-
Fig. 1 presents part of a disk of the invention and
of the tire which is being worked on, in cross section.
Fig. 2 shows the section carrled along the line II-II
in Fig. 1, on an enlarged scale~
Flg. 3 shows the section of the ring-shaped cutting
bit, carried along the line III III in Fig. 2, on a further
enlarged scale.
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Fig. 4 is a sectioned partial ~iew presenting another
embodiment of the invention, wherein the cutting angle of the
cutting bits has been arranged to be a~justable.
In the case depicted in Fi~. 1, the cutting disk
rotates at right angles to the direction of rotaticn of the tire
10. The cutting disk 1 consists of two disks 12 and 13 mounted
side by side and affixed to each other ~y screws 1~. ~he
peripheral faces of the disks 12 and 13 have been so shaped that
bet~een their rims remains a groove 9 having a cross section with
the form of a partial circle. In ~his groove ring-shaped cutting
bits 2 have been disposed, which have been tightly impacted
between the disks 12 and 13 by the aid of screws 14~ For
increased security of their fixiny, the cutting ring 2 has on its
outer side an encircling groove 3, which is entered by the strips
4 on the disks 12 and 13. In order that all cutting bits ~
might be positively impacted between the disks 12 and 13 in spite
of their dimensional differences due to manufacturing tolerances,
slits 5 have been provided on the circumference of the disks 12
and 13 to separate sector parts, each of which contain5 two cutting
bits 2 and one fixing screw 14.
Both edges of the cutting ring 2 serve as cutting bits
6, whereby the disk 1 may be rotated in either direction. The
disk 1 may be provided in a manner known in prior art with a
reversing mèchanism, the reversing of direction taking place over
the centre of the tire and the cutting always being towards the
outer edge of the tire. To this purpose the disk 1 has been fitted
with a mechanism not depicted, to be displaceable in the transverse
direction of the tire. In view of producing a roughened surface
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after c~ltting, the ring 2 has on its outer ~urface, grooves 7
paralleling its axi~. The cutting grooves produced by the rings
2 as well as the rou~hening grooves produced by the xoughenings 7
are transversal to the tire and therefore they do not interfere
with the degassing carried out in connection with the resurfacing
of the tire.
As the cutting disk I rotates, the cutting edyes 6 of
the cutting ring 2 cut from the wearing surface strip-shaped
pieces, which depart through the aperture 8 of the cutting ring 2.
With a speed of the disk 1 about 2000 to 3000 r.p.m., the risk
of heating of the cut rubber is extremely high. When cutting
rings according to the invention are used, the cutting process as
well as the chip removal will be ideal, in addition to which the
cutting bits are cooled by the air flowing through the aperture 8,
and no detrimental heating will occur. It follows that the work
is fast, since no interruptions for cooling are necessary, nor for
removal of the rubber mass that ha~ been heated and vulcanized
to adhere to an~ clog the cutting bits.
The cutting bits 2 may be made of sintered hard metal,
or ceramic bits may be used as well.
Fig. 4 displays another embodiment of the invention,
wherein the cutting angle of the cutting ring 2' has been arranged
to be adjustable or even to be automatically changeable when the
direction of rota~ion of the disk l' is reversed. In this case,
too, the disk 1' may consist of two disks 12l and 13' fixed against
each other and into which appropriate receiving sockets 9' have been
machined for the cutting rings 2'. ~rom the cutting ring 2' an
a~m 15 extends through an aperture in the disk 12', its end being
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pivotally connected with a third disk 16~ The disk 16 r~tates
along with the diisk 1', but it has the freedom of movement through
a given angle with reference to thie disk 1'. By means of a
friction plate 17, the turning of the disk 16 through the said
angle with reference to the disk 1' may be caused every time when
the rotation of the disk 1' is reversed. It is possible to use
instead of the fric~ion plate 17, a fi æ d setting between the
disks 1' and 16 so that the cutting angle of the cutting ring 2
may be adjus~ed to any desired value. Such fixed set~ing is
possible in practice owing to the fact that it has been found that
the de~icP of the invention may be used to machine a tire without
periodic changes of the direction of rotation and yet there is no
risk of damage to the supporting structures of thie tire, such as
the radial ply course.
Al~hough most favourahly the fixing of the cutting rings
2 is between two disks 12, 13, thie fixing may also be accomplished
by means of a hoop passed thirough the apertures 8 and which urges
thie rings into a groove on thie outer circumference of the unitary
disk.
Generally considered7 the speed of rotation of the
disk 1 is about ten times that of the tire 10.
It is not absolutely necessary that the cutting rings
have the shape of closed rings: cut~ing bit~ shaped like part of
the ring, or like thie letter C, may also be used. The shape of
the rings ne~d not be circular. it may as well be oval, for
instance.
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