Patent Grant
9138870
Applicant claims priority under 35 U.S.C. §119 of German Application No. 10 2011 108 859.1 filed Jul. 28, 2011, the disclosure of which is incorporated by reference.
1. Field of the Invention
The invention relates to a rotationally symmetrical tool for cutting material surfaces with several disks or ring disks arranged for metal-cutting, which comprise an incision originating from the outer circumference, comprise a common rotational axis and are stacked in a partly overlapping manner on top of one another in such a way that a portion of one respective disk or ring disk comes to lie on top through the incision of a disk or ring disk disposed above, with the incisions of the disks or ring disks being angularly offset. Furthermore, the invention relates to disks or ring disks with which the tool is arranged, and a method for the production of said tool.
2. Description of the Related Art
Generic rotationally symmetrical tools which are used for cutting material surfaces usually comprise one or several disks or ring disks with active metal-cutting properties. The cutting of material surfaces includes grinding, lapping, honing, polishing or mixed forms thereof. Active metal-cutting properties are then derived from grinding bodies, lapping means, polishing cloths or polishing pastes.
Rotationally symmetrical tools are known from the prior art, which comprise two circular ring disks which are interlocked in the manner of a fan. These tools are used in the grinding of tubes and boreholes or during deburring for example. As a result of several incisions in each ring disk, the tool is flexible and can adjust to the shape of the material surface. In order to interlock the ring disks, a first ring disk is provided with radial incisions and a second ring disk is cut to size in such a way that several trapezoidal segments of a circle are produced. The ring disks are placed on top of one another in such a way that they have a common rotational axis and the first ring disk comes to lie on the second one. The circle segments of the second ring disk are slid through the radial incisions of the upward first ring disk in such a way that circle segments of the second ring disk overlap the cover surface of the first ring disk and come to lie on the same.
The disadvantageous aspect of the tools known from the prior art is the low number of cover surfaces of the ring disks involved in the metal-cutting process, which is limited to two. Furthermore, production is very laborious because the shapes of the incisions differ in the two ring disks and the sliding and interlocking of the two multiply incised ring disks cannot be automated in a cost-effective manner.
It is therefore the object of the invention to provide a rotationally symmetrical tool for cutting which can be produced by a cost-effective and automated method that can be realized with few work steps and offers a higher material removal rate in combination with longer service life.
This object is achieved by the rotationally symmetrical tool in such a way that the incision reaches up to the center point of the disks or the inner circumference of the ring disks, and that the angular offset to the incision of the respectively next disk or ring disk is equal to α=360°/n, with n being the number of the disks or ring disks. The object is achieved with respect to the method in that several disks or ring disks arranged for metal-cutting are incised from the outer circumference up to the center point of the disks or the inner circumference of the ring disks, the incisions of at least two disks or ring disks are slid completely into each other, the disks or ring disks are folded towards one another until their rotational axes are aligned coaxially with respect to one another, and finally the partly overlapping disks or ring disks are mutually twisted until an angular offset of the incisions of the respectively next disk or ring disk equal α=360°/n is reached, with n being the number of the disks or ring disks. Preferred further developments are discussed below.
It is provided in accordance with the invention that the rotationally symmetrical tool for cutting material surfaces is provided with several disks or ring disks arranged for metal-cutting. The disks or ring disks can be circular, elliptic, polygonal, rosette-like or star-shaped. When the disks or ring disks are completely slid into each other at their incisions and folded towards one another so that the cover surfaces (i.e. the upper and bottom sides of the disks or ring disks) touch one another and the rotational axes are coaxial and are thereafter mutually twisted, an overlapping stacking of the individual disks or ring disks is obtained. A portion of a disk or ring disk engages through the incision of the next upper disk or ring disk and comes to lie on its cover surface. The angular offset of the incisions of the directly adjacent disks or ring disks can be determined by twisting the disks or ring disks.
The invention comes with the advantage that only one incision is provided per disk or ring disk and said incision reaches up to the center point of the disk or the inner circumference of the ring disk, by means of which the disks or ring disks can be slid in a simple manner into each other and can be displaced against one another.
It is further advantageous that all disks or ring disks of a tool are evenly involved in the cutting process, which increases the material removal rate of the disks or ring disks and therefore increases the service life of the tool. The disks or ring disks are consumed by removal in areas which come into contact with the material surface during the cutting process. This always only affects the uppermost layer of the stacked and overlapping disks or ring disks. All disks or ring disks are involved in the uppermost layer, with the fraction of the cover surface of each disk or ring disk which forms the uppermost layer being equal to 1/n. This is in agreement with the angular offset of α=360°/n which the incisions of the respectively adjacent disks or ring disks have with respect to each other. Once the uppermost layer has been consumed by the cutting process, the next layer underneath which is again formed from the stacked and overlapping disks or ring disks will be removed. In the case of constant wear, the ratio of the surface fractions of the cover surfaces active in the cutting will not change, which means it will remain at 1/n. Since the tool needs to be fitted with new disks or ring disks only after the consumption of all disks or ring disks, longer service life is ensured in comparison with tools which are covered with one disk or covered with only few disks or ring disks.
A preferred embodiment of the invention is that the number of the disks or ring disks is three to six and preferably four to five. The larger the number of the stacked and overlapping disks or ring disks, the longer the active cutting properties of the disks or ring disks can be used before an exchange will become necessary.
Principally, the incision can be a thin slit, with the cover surface of the disk or ring disk being maintained completely. The incision can also be produced in such a way that a portion of the cover surface of the disks or ring disks is cut away. The shapes of the incisions of the disks or ring disks can vary widely, e.g. they can be straight, arc-shaped or wave-like, linear, rectangular, triangular or trapezoidal. In accordance with a preferred further development of the invention, the incisions will widen towards the outer circumference. This means that the width of the incision or the cut shape will increase from the center point of the disk or the inner circumference of the ring disk up to the outer circumference. This is advantageous in that the disks or ring disks can be slid into each other and twisted more easily because there will be less friction between the disks or ring disks among each other. This is especially useful when many disks or ring disks need to be twisted with each another. Usually, the incision of at least one disk or ring disk at the narrowest point is at least wide enough to allow for n−1 stacked disks or ring disks to be pushed into the incision.
The incisions of the rings can principally extend radially or tangentially from the outer circumference to the inner circumference. In an especially preferred variant, the incisions will extend radially to the inner circumference. A radial incision extends from the outer circumference up to the centric opening of the ring, with the extension of the incision ending at the imaginary center point of the ring disk. A tangential incision also reaches from the outer circumference up to the ring opening, but the extension of the incision does not meet the imaginary center point but ends adjacent to the center point. Radial incisions offer the advantage that they are shorter than tangential incisions. As a result, there is a lower likelihood that the mutually stacked disks or ring disks will get jammed as a result of the incisions at high rotational speed, or that the transitional points of mutually stacked disks or ring disks will right up at the incisions.
In a preferred embodiment, the disks or ring disks comprise adjusting aids which determine the angular offset. The adjusting aids are arranged on the disks or ring disks in such a way that they determine the adjustment and therefore the angular offset of the incisions during displacement of the disks or ring disks. The adjusting aids can be based on a specific shape or color such as punched portions or marking points. The measurement of the angular offset will become superfluous due to the adjusting aids because said angular offset will inevitably be set by the alignment of the disks or ring disks on the adjusting aids.
Principally, the adjusting aids can be disposed at any location of the disks or ring disks. The adjusting aids can be provided in form of marking points on the outer circumference. However, they can also occur in the cover surface of the disks or ring disks in form of punched portions or perforations. In an especially preferred variant, the adjusting aids are disposed on the inner circumference of the rings. For example, the adjusting aids can be arranged as a straight side of an otherwise circular centric ring opening.
In a further especially preferred embodiment, the adjusting aids of the individual disks or ring disks together form an adjusting pattern, which will only be obtained if the alignment of the disks or ring disks corresponds to the angular offset of the incisions. Thus, when stacking the disks or ring disks on top one another, the angular offset of the incisions can be produced by twisting the disks or ring disks until the adjusting pattern appears. The adjusting pattern can be a perforation for example which is brought to fully overlap in all disks or ring disks. In this process, each of the mutually stacked disks or ring disks comprises a circular perforation in its cover surface. The perforations are arranged on a circular circumference which is equally distant from an imaginary center point on the individual disks or ring disks and only differs in respect of their position to the respective incision of the disk ring disk. When the disks or ring disks are twisted until the perforations of all disks or ring disks fully overlap each other, i.e., the adjusting pattern has been obtained, the angular offset of 360°/n has been set.
In the event that the adjusting aids are formed as straight sides of otherwise circular centric ring openings, the angular offset of the incisions is obtained when after the displacement of the ring disks the adjusting aids or the centric ring openings of all ring disks jointly assume a polygonal shape. The precondition for this is that all ring disks have the same configuration, which means that the centric openings are provided with the same shape and the incisions are located at the same place in all ring disks. If the centric ring openings are arranged with a non-rotationally symmetrical shape, e.g. as a semicircle, the incisions in the individual ring disks respectively need to be offset by a specific angle in relation to the respective adjusting aid (the straight side of a semicircle for example) in order to produce the angular offset of the incisions by means of the adjusting pattern (a semi-circular ring opening which is matched so as to fully overlap in all disks or ring disks).
The production of the rotationally symmetrical tool with the disks or ring disks can be automated with the help of the adjusting aids or the resulting adjusting patterns. Mounting or bearing supports are used for the purpose of aligning the disks or ring disks on the adjusting aids according to the angular offset. The subsequent measurement of the angular offset can be avoided by using the adjusting aids.
In order to prevent fluttering of the disks or ring disks during rotating operation of the tool, it is appropriate to glue the disks or ring disks together at least in part. In a preferred further development, the adhesive is applied at certain points close to the incision of a disk or ring disk. This can be provided as a point-like application or in form of a bead. Planar coating of the disks or ring disks is principally not necessary in order to prevent fluttering in operation. Suitable adhesives are polyurethane, cold or hot adhesives for example.
Principally, the disks or ring disks are provided with active cutting properties at least on one of their cover surfaces, i.e. the upper or bottom side. A preferred variant of the invention provides active cutting properties both for the upper as well as the bottom cover surface of the disks or ring disks. This arrangement comes with the advantage that both the uppermost and lowermost cover surface of the stacked disks or ring disks are involved in the cutting process. This can be especially useful when the tool is used for machining grooves, flutes, boreholes, slits or the inside diameter of a tube. Surfaces of the disks or ring disks with active cutting properties will meet the material surface both during insertion and withdrawal of the tool. The tool will automatically adjust to the shape of the material surface as a result of the flexible disks or ring disks.
The materials which are responsible for the active cutting properties of the disks or ring disks differ depending on the field of application. Preferably, at least one of the disks or ring disks comprises a nonwoven or felt material in accordance with the invention. Both the nonwoven and the felt material are suitable for the preliminary polishing of soft materials such as aluminum, brass or copper, because the surface roughness of the material surface will be reduced and smoothing will be achieved. The mirror finish of the material surface is achieved by using the nonwoven material in combination with polishing pastes and creams. Foamed, highly refined nylon nonwoven is used on the other hand for grinding, finishing grinding, descaling, removal of oxides, scratches, rust, burrs and paint from metals, wood and plastic. Grain-distributed coarse nylon fabric is used for cleaning and descaling weld seams, and cleaning metals and wood. Disks or ring disks made of cotton are used for polishing soft metals together with polishing pastes and creams.
Furthermore, preferably at least one disk or ring disk consists of a support and a material machining coating. The disk or ring disk is provided with stability by the support. The support can consist of nylon, polyester, cotton or mixed fabric, vulcanized fiber or knitted hemp, flax or sisal fabric.
The material machining coating can principally consist of an abrasive agent, nonwoven material, felt material, or a polishing cloth. An especially preferred further development is provided with a material machining coating which consists of an abrasive with a grit of 35 to 60 (ISO 6344). This grit of the abrasive comes with the advantage of ensuring high removal in combination with low damage to the material surface. The abrasives are bonded to the support by using predominantly ceramic, polymer or metal bonding agents. Abrasives to be considered are oxidic cutting ceramics, diamond particles, silicon carbide, corundum or zircon. Preferably, the abrasive comprises ceramic components which in pure or mixed form consist of aluminum oxides, zirconium oxide, titanium carbide, zirconium corundum or silicon carbides. The use of abrasives with ceramic components as a material machining coating produces an especially high removal rate in the tool in accordance with the invention because the grinding angle obtained between the tool and the surface of the material is acute as a result of the overlapping, mutually stacked disks or ring disks.
In a further preferred embodiment, the active cutting properties of at least two disks or ring disks differ from one another. It is therefore possible to combine an abrasive disk with a nonwoven disk, which leads to the consequence that the uppermost cover layer which is involved in the cutting process consists of two different materials and has different active cutting properties. Processing steps in metal-cutting of a material surface by a tool can be combined with this arrangement without requiring an exchange of the disks or ring disks or of the tool.
In a further embodiment in accordance with the invention, the disks or ring disks are arranged on a supporting disk. As a result of the support of the disks or ring disks by a supporting disk, the tool will become more stable and the force required for the metal-cutting process which is applied to the tool for machining the surface can be transmitted in this way more efficiently to the material surface. The disks or ring disks are fixed with an adhesive to the supporting disk, which adhesive has a residual elasticity. The adhesive can be provided on the basis of polyurethane or can be a hot or cold adhesive.
In an especially preferred embodiment, the disks or ring disks are attached to the supporting disk by a detachable adhesive or a hook-and-loop fastener. This facilitates and accelerates the mounting of the disks or ring disks on the supporting disk when an exchange becomes necessary.
The supporting disk is connected via a clamping system, a flange or a thread with a drive shaft of a drive machine such as an angle grinder. The tool in accordance with the invention offers the advantage that it is possible to work at a speed of the drive machine in the range of 50 to 80 m/s (DIN EN 13743). Optimal performance and service life of the tool is achieved at a speed of 63 m/s.
Principally, the supporting disk can consist of different materials. Vibration-damping and noise-damping plastic materials such as polyurethanes or acrylonitrile butadiene styrene are used for example. It is appropriate to use free-machining materials which are easy to trim and wear off automatically during the machining of the surface. Such a material is a plastic such as acrylonitrile butadiene styrene for example. In a preferred embodiment, the supporting disk comprises natural fibers which can easily be disposed of after use. Such a supporting disk can be made of granulates for example by way of an injection molding method, with the granulate consisting of hemp fibers or cellulose in a bonding agent. It is also possible to use a plastic supporting disk which is reinforced with natural fibers.
For the production of a rotationally symmetrical tool in accordance with the invention for cutting material surfaces, the disks or ring disks are preferably pre-sorted into stacks before being slid into each other. The sliding of the disks or ring disks into each other then occurs in stacks, which substantially facilitates the production of the tool. In a preferred further development, the sequence which the future stacked disks or ring disks slid into each other will have is determined by preceding sorting within the stack. The folding together towards one another then determines the final sequence of the two stacks and therefore of all disks or ring disks.
In order to prevent fluttering of the disks or ring disks during rotating operation, adhesive is applied close to the incisions of the disks or ring disks in some sections during the production of the tool. The adhesive can be applied before or after the production step in which the disks or in disks are slid into each other. The gluing in some sections can occur in form of individual adhesive points or adhesive beads. It is advantageous when a supporting disk is used to fix the disks or ring disks to the same by means of adhesive. The lowermost layer of the mutually stacked disks or ring disks is glued together with the upper side of the supporting disk. The adhesive can be applied either in some sections or in a planar fashion on the supporting disk or the disks or ring disks, or on both. Suitable adhesives are polyurethane, cold or hot adhesives.
The invention will be described below in closer detail by reference to the five preferred embodiments shown in the drawings, which show schematically:
The production of a first tool 5 with two (n=2) circular disks 18 and 19 arranged for cutting will be described below by reference to
The three mutually inserted ring disks 10′, 10″ and 10′″ comprise a common rotational axis 17, and both the ring openings 11 and also the outer circumferences 13 of the three ring disks 10′, 10″ and 10′″ come to lie on top of one another. The ring disks 10′, 10″ and 10′″ will engage into each other via their incisions 12′, 12″ and 12′″, and are displaced against one another in such a way that an angular offset of α=360/n=120° is obtained between the incisions 12′ and 12″, 12″ and 12′″ and 12′″ and 12′. As a result, the ring disk 10′ engages through the incision 12′″ and comes to lie on the ring disk 10′″. The ring disk 10′ is involved with one-third in the uppermost layer of the mutually stacked three ring disks 10′, 10″ and 10′″, whereas two-thirds of the ring disk 10′ are covered by the ring disks 10″ and 10′″ disposed above. Ring disk 10″ engages through the incision 12′ and comes to lie on the ring disk 10′. One-third of the ring disk 10″ is involved again in the uppermost layer, whereas two-thirds of the ring disk 10″ are covered by the ring disks 10′″ and 10′ disposed above. The same applies to ring disk 10′″, which engages through the incision 12″ and comes to lie on ring disk 10″. Two-thirds of the ring disk 10′″ are covered by the ring disks 10′ and 10″ disposed above and one-third of the ring disk 10′″ is involved in the uppermost layer. The perspective view (
In order to produce a third tool 7 according to
Once the ring disks 10a to 10d have been twisted against one another to such an extent that an angular offset of α=360/n=360°/4=90° has respectively been set between the incisions 12a and 12b, 12b and 12c as well as 12c and 12d, a square adjusting pattern 22 is obtained. The square shape is only obtained if the ring disks 10a to 10d have been twisted against one another in such a way that the adjusting aids 21a to 21d form a square with their otherwise circular ring openings 11. If the square adjusting pattern 22 is not obtained during the twisting of the ring disks 10a to 10d, ring disks 10a to 10d need to be displaced to such an extent into each other until the square ring opening 11 is obtained. The angular offset of 90° is then set between the incisions 12a to 12d, which means incision 12a is offset by 90° in relation to incision 12b, incision 12b is offset by 90° to incision 12c, incision 12c is offset by 90° to incision 12d, and incision 12d is offset by 90° again to incision 12a. As a result, ring disk 10a is visible to one-quarter and covered to three-quarters by the upper ring disks 10b, 10c and 10d. The remaining ring disks 10b to 10d are subject to the same layering scheme.
The tools made of disks 19 or ring disks 10 according to
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2011 108 859 | Jul 2011 | DE | national |
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| Number | Date | Country | |
|---|---|---|---|
| 20130025429 A1 | Jan 2013 | US |
