The present disclosure relates to abrasive cutting tools for processing hard materials such as concrete, reinforced concrete, and stone. There are disclosed cutting segments and saw blades comprising the cutting segments, as well as related work tools and construction equipment.
It is known to use diamond tools for cutting hard materials such as concrete, reinforced concrete and stone. Diamond tools normally use cutting segments arranged on the periphery of a rotatable disc which engages the material to be cut in an abrasive manner.
In order to promote an efficient cutting operation, it is desired to minimize friction on surfaces of the cutting segment which are lateral to the direction of the cut.
During operation dust and/or slurry is generated which needs to be transported away from the cutting area in order to not reduce cutting performance. It is therefore desired to promote evacuation of the dust and/or slurry which is generated during cutting from the cutting area.
US2010291845 discloses a diamond tool where diamond granules are arranged at outer peripheries of cutting segments and placed in a radial pattern from a centre of a shank of the diamond tool, so that a constant cutting force is maintained even though the segments are worn out, and thus, the same cutting force is maintained during the service life of the diamond tool.
US20060130823A1 and in WO2002066217A1 also disclose cutting segments and diamond tools for cutting hard materials such as concrete, reinforced concrete and stone.
However, there is a need for more cost-efficient cutting segments allowing improved cutting action in terms of, e.g., cutting speed and segment lifetime.
It is an object of the present disclosure to provide improved cutting segments, saw blades and work tools for cutting hard materials such as reinforced concrete and stone by abrasive operation which alleviate at least some of the above-mentioned issues.
This object is obtained by a cutting segment for mounting onto a saw blade to provide an abrasive operation by the saw blade. The cutting segment comprises a body having a cutting surface facing in a cutting direction of the cutting segment, and side surfaces facing laterally with respect to the cutting direction. A plurality of protrusions extends laterally from the side surfaces. The cutting segment constituted by the body and by the protrusions is formed by a homogenous mixture of metal powder and diamond granules.
Since the whole cutting segment is formed by a single homogenous mixture of metal powder and diamond granules it can be manufactured in an efficient and cost-effective manner, e.g., by cold pressing the cutting segment.
Some of the protrusions may comprise a diamond granule and some protrusions may only comprise metal. However, statistically, a fraction of the protruding elements will comprise diamond granules that will protect the cutting segment from lateral wear. The protrusions extend out laterally from the side surfaces of the cutting segment, which means that the protrusions will make contact in lateral direction with the work object to be cut, and not the side surfaces. This means that the protrusions reduce lateral friction forces acting on the cutting segment and also promote evacuation of dust and slurry from the cutting zone during operation, which is an advantage.
Advantageously, there is no need to attach protrusions such as diamond granules one-by-one to the sides of the cutting segment since the cutting segment is instead formed by a homogenous mixture of metal powder and diamond granules. This means that, statistically, the fraction of diamond granules is the same throughout the cutting segment.
According to some aspects, the mixture of metal powder and diamond granules in the cutting segment comprises between 90% and 97% metal powder and correspondingly between 10% and 3% diamonds by volume. This range of volume proportions has been found to give good results in terms of cutting efficiency and lifetime of the cutting segment.
The protrusions may have different shapes and sizes. For instance, the protrusions may be hemispherically shaped with a base radius between 0.3 mm and 1.0 mm, and preferably about 0.70 mm, and with a height between 0.2 mm and 0.6 mm, and preferably about 0.40 mm. Hemispherical protrusions allow for an efficient manufacturing process of the cutting segment, and at the same time provide an increased cutting efficiency of the cutting segment due to, e.g., reduced lateral friction. The protrusions may also be of other shapes, such as cylinders, beveled cylinders, rectangles, or beveled rectangles. Generally, the protrusions are delimited by boundaries on the side surfaces, such that at least two protrusion boundaries are separated from each other and from the cutting surface by a portion of side surface.
According to some other aspects, the cutting segment comprises a longitudinal wear indicator groove extending in the cutting direction and facing laterally with respect to the cutting direction. This longitudinal wear indicator groove provides a visual indication of the level of longitudinal wear suffered by the cutting segment. An operator can therefore easily detect when it is time to replace the saw blade.
According to some other aspects, the cutting segment comprises a lateral wear indicator groove formed in one or both of the side surfaces and facing laterally with respect to the cutting direction. The lateral depth of this lateral wear indicator groove is indicative of an acceptable lateral wear of the cutting segment. This lateral wear indicator groove provides visual indication of lateral wear. Thus, similar to the longitudinal wear indicator groove, an operator may visually determine the current lateral wear, and thus determine when it is time to replace the saw blade.
According to further aspects, the protrusions are arranged on offset curved lines. This arrangement of protrusions has been found to yield improvements in cutting efficiency. The curved lines may, e.g., be given by circle segments drawn from a circle with a center which has been offset from a longitudinal centrum line of the cutting segment and from a top line of the cutting segment, as will be explained below. This particular arrangement of the protrusions improves cutting efficiency of the cutting segment while still being easy to manufacture.
According to other aspects, a recess is formed with a lateral extension in the cutting surface. This recess has been shown to reduce undercutting effects, which is an advantage.
The object is also obtained by a saw blade comprising a plurality of cutting segments according to the above, arranged along a peripheral edge of the saw blade. This saw blade can be manufactured in a cost efficient manner and provides excellent cutting efficiency in terms of cutting speed. Some aspects of the proposed saw blade offer improvements up to or even in excess of 20% in cutting speed and about 10% increase in cutting segment lifetime compared to some known saw blades.
According to other aspects, the cutting segments arranged along the peripheral edge of the saw blade are of at least two types, where the cutting segments of the at least two types are interleaved along the peripheral edge of the saw blade. By arranging different types of cutting segments along the periphery of the saw blade, the saw blade can be optimized for different types of materials to be cut in a simple and cost efficient manner, since only a few types of cutting segments are required for a wide range of different optim izations.
There are also disclosed herein work tools and construction equipment associated with the above-mentioned advantages.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to “a/an/the element, apparatus, component, means, step, etc.” are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. The skilled person realizes that different features of the present invention may be combined to create embodiments other than those described in the following, without departing from the scope of the present invention.
The present disclosure will now be described in more detail with reference to the appended drawings, where
The invention will now be described more fully hereinafter with reference to the accompanying drawings, in which certain aspects of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments and aspects set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout the description.
It is to be understood that the present invention is not limited to the embodiments described herein and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims. This applies in particular to the example dimensions of the cutting segments and the saw blades described below.
A homogeneous mixture is herein to be interpreted as a mixture of particles and/or granules that has approximately the same proportions of its components throughout any given sample. It is appreciated that the proportions of particles throughout the mixture may differ slightly due to randomization. A homogenous mixture of metal powder and diamond granules can, for instance, be obtained by adding the metal powder and the diamond granules to a container and then stirring or shaking the mixture until a homogenous mixture is obtained.
Generally herein, dimensions will be given in millimeters (mm). It is appreciated that the measures given are purely by way of example in order to illustrate how the disclosed cutting segments and saw blades may be realized in practice.
A cutting direction C of the saw blade 100 is a direction extending from the center of the blade towards the peripheral edge E and beyond. This is the direction in which the saw blade engages the material to be cut.
The intended direction of rotation of the saw blade is indicated by an arrow 120, which is optionally cut into the saw blade or otherwise marked on the saw blade.
The cutting segments 110 are separated by inclined slots 130, which are terminated by holes of diameter slightly larger than the width of the inclined slot. These inclined slots promote evacuation of dust and slurry during cutting operation. The inclined slots may have a width of about 2 mm, and an inclination angle of about 30 degrees. These inclined slots promote evacuation of dust and slurry, and also promotes cooling of the cutting segments during cutting operation.
Measuring holes 140 are arranged along a circle centered on the saw blade center 170 and with radius smaller that a radius of the saw blade. The measuring holes allow for measurement of cutting segment wear, e.g., by calipers.
The measuring holes 140, together with a second set of holes 150 also arranged on a circle, form a cutting depth indicator arrangement. The first set of holes 140 may be arranged about 1 inch from the cutting segment edge, and the second set of holes 150 about 2 inches from the cutting segment edge. This way an operator may visually determine approximate cutting depth during operation.
A pin-hole 160 is arranged in connection to the blade center 170 for mounting the blade onto a tool.
The difference between a groove and a protrusion is clearly seen in
The cutting segment 110, constituted by the body 200 and by the protrusions 230, is formed by a homogenous mixture of metal powder and diamond granules. That is to say, the protrusions are not attached one-by-one to the body, but rather integrally formed in one piece together with the body. Thus, since the whole cutting segment is formed by a single homogenous mixture of metal powder and diamond granules it can be manufactured in an efficient and cost-effective manner, e.g., by cold pressing the cutting segment. Some of the protrusions may after manufacturing by chance comprise one or more diamond granules and some protrusions may only comprise metal. However, statistically, a fraction of the protruding elements will comprise diamond granules that protect the cutting segment from lateral wear. According to some aspects the size of the diamond granules is selected to be on the order of the size of the protrusions, but not larger than the protrusions since then no diamond granules will protrude from the body 200.
By laboratory experiments, it has been found that a mixture of metal powder and diamond granules comprising between 90% and 97% metal powder and correspondingly between 10% and 3% diamonds by volume is desired in order to provide an efficient cutting operation in a wide range of materials, such as reinforced concrete and stone.
With reference to
According to some aspects, the protrusions 230 are arranged on offset curved lines 240A, 240B, schematically indicated in
The cutting segment 110 optionally also comprises a longitudinal wear indicator groove 250 extending in the cutting direction C and facing laterally L with respect to the cutting direction C. A cross-sectional view taken through this longitudinal wear indicator is shown in
The combination of the longitudinal wear indicator groove and the protrusions has been found to yield a particularly effective cutting segment.
The cutting segment 110 optionally also comprises a lateral wear indicator groove 260 formed in one or both of the side surfaces 220 and facing laterally L with respect to the cutting direction C. A lateral depth of the lateral wear indicator groove 260 is indicative of an acceptable lateral wear of the cutting segment 110 and can be configured by the designer of the saw blade according to the type of cutting segment and intended use. Thus, an operator may visually determine the current lateral wear, and thus determine when it is time to replace the saw blade.
The combination of the lateral wear indicator groove and the protrusions has been found to yield a particularly effective cutting segment.
Both the longitudinal and the lateral wear indicator also facilitate evacuation of dust and slurry from the cutting zone, by transporting dust and slurry out and away from the cut as the saw blade rotates.
The lateral depth of the lateral wear indicator groove 260 may be on the order of between 0.3 mm and 0.7 mm, and preferably about 0.5 mm.
The height and width of the lateral wear indicator groove 260 may be configured between 2 mm and 4 mm and 3.5 mm and 5.5 mm, and preferably 3 mm and 4.75 mm, respectively.
It is appreciated that the protrusions 230 may be formed with different geometrical shapes.
It is appreciated that a protrusion differs from a groove formed in the side surface. While a protrusion extends laterally out from the side surface, a groove extends laterally inwards towards a center of the cutting segment. As exemplified in
The cutting segment body width 280 may be between 3.5 mm and 4.0 mm, and preferably 3.7 mm, as shown in
A protrusion is also localized on the side surface, whereas a groove is elongated and has an extension direction along which it extends. According to some aspects, the protrusions discussed herein are confined by a respective protrusion boundary within an area on the side surface of between 0.28 mm2 and 3.14 mm2 for the round protrusions, which, according to some aspects, also hold true for other shapes of protrusions. The protrusions are delimited by protrusion boundaries on the side surface planes P1, P2, and the boundaries are separated from the cutting surface 210 by a distance. In other words, there is a portion of side surface 220 in-between at least two protrusions 230, and preferably in-between any two protrusions, or at least in-between a majority of the protrusions.
Generally, a protrusion, regardless of its geometrical shape, is confined within a surface area on the side surface of between 0.28 mm2 and 3.14 mm2. This means that the sides S1 and S2 are on the order of twice the radius R, as illustrated in
The cutting segments disclosed herein comprise a cutting surface 210. This cutting surface is associated with a normal vector, which, in the example of
The protrusions 230 may, as noted above, be formed with different geometrical shapes. Each such shape is associated with a geometric center, or centroid, i.e., an arithmetic mean position of all the points in the shape. In the cutting segments disclosed herein, as exemplified by, e.g.,
The recess 420 has been shown to reduce such undercutting effects, which is an advantage.
A third type of cutting segment 510 optionally has a height 270 larger than at least one other cutting segment on the saw blade 700 as shown in
Number | Date | Country | Kind |
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2050932-9 | Aug 2020 | SE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2021/071700 | 8/3/2021 | WO |