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Patent Searching and Data


Title:
TOOL WITH TOOL ELEMENTS
Document Type and Number:
WIPO Patent Application WO/2017/207008
Kind Code:
A1
Abstract:
A tool (1) with tool elements (4), preferably rotating grinding and/or sanding tool. The tool (1) consists of a tool portion (2) and a mounting portion (3), which secures the tool elements (4) in the tool (1). The tool (1) is distinguished in that the tool portion comprises first mounting means, and the mounting portion comprises second corresponding mounting means for engaging with the first mounting means. The first and second mounting means comprise one or more resilient tabs (10), each of which is provided with at least one barb, and furthermore the mounting means comprise one or more recesses (18). When the tool portion (2) and the mounting portion (3) are assembled, the barbs (15) on the resilient tabs (10) will lock in the recesses (18) of the mounting portion which are designed for this, locking the tool portion (2) and the mounting portion (3) to each other. This produces a design which is easy to assemble. Furthermore, it achieves a tool (1) having a cheap design, suitable for onetime use.

Inventors:
JESPERSEN, Poul Erik (Durupvej 17, Glyngøre, 7870 Roslev, 7870, DK)
Application Number:
DK2017/050180
Publication Date:
December 07, 2017
Filing Date:
May 31, 2017
Export Citation:
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Assignee:
KADICMA APS (Hedelund 28, Glyngøre, 7870 Roslev, 7870, DK)
International Classes:
B24D9/08; B24B45/00; B24D13/20
Attorney, Agent or Firm:
PATRADE A/S (Fredens Torv 3A, 8000 Aarhus C, 8000, DK)
Download PDF:
Claims:
PATENT CLAIMS

1. A tool with tool elements, preferably grinding and/or sanding elements, which tool is designed for mounting on a machining unit with a motor, which rotates the tool via a drive shaft, which tool comprises a mounting portion and a tool portion, where the tool portion comprises grooves to receive the tool elements, where the mounting portion comprises fastening means for fastening the tool, directly or indirectly, to the drive shaft, wherein the tool elements are secured in the tool portion, after the tool is assembled by connecting the mounting portion and the tool portion,

characterized in that

the tool portion comprises first mounting means,

the mounting portion comprises second corresponding mounting means for engaging with the first mounting means, and

the first and second mounting means comprise one or more resilient tabs, each of which is provided with at least one barb, and the mounting means furthermore comprise one or more recesses for receiving said barbs with a snap action in the assembled state of the tool for locking of the tool portion and the mounting portion to each other with the tool elements secured in the grooves. 2. The tool according to claim 1, characterized in that the tool portion has a first inner wall, which is directed toward the mounting portion, the mounting portion has a second inner wall, which is directed toward the tool portion, and the radial outer surface of the second inner wall is dimensioned such as to be enclosed by the first inner wall when the tool is in the assembled state, and in connection with the first inner cylindrical wall or in openings in the first wall there are arranged resilient tabs with barbs,

and along the radial outer side of the second inner wall in the mounting portion there are arranged a number of recesses in the mounting portion, corresponding in position, shape, and number to the tool portion's resilient tabs.

3. A tool according to any one of the preceding claims, characterized in that along the periphery of the tool portion there are arranged a number of pins, and along the periphery of the mounting portion there is devised a slot, in which the tool portion's pins are designed to engage in order to secure the periphery of the tool portion to the mounting portion.

4. A tool according to claim 3, characterized in that the slot is arranged in the periphery of the mounting portion or on a radially inner surface of an outer wall, which outer wall is directed substantially toward the tool portion along the periphery of the mounting portion.

5. A tool according to claim 4, characterized in that the slots for the tool elements are formed as slits which are open or closed at the periphery of the tool portion.

6. A tool according to any one of the preceding claims, characterized in that at least one guide groove is placed in the first inner wall of the tool portion, and on the mounting portion there is placed at least one guide pin in connection with the second inner wall of the mounting portion, so that the guide pin is designed to engage with the guide groove when assembling the tool portion and the mounting portion.

7. A tool according to any one of the preceding claims, characterized in that the tool portion is formed as a disk, a cylinder, a conical shape, or with a curved shape, such as a concave or convex shape.

8. A tool according to any one of the preceding claims, characterized in that the outer periphery of the tool has one of the following shapes: round, oval or polygonal, such as triangular, rectangular, pentagonal, hexagonal, heptagonal, octagonal.

9. A tool according to any one of the preceding claims, characterized in that the tool elements are mounted in base pieces, which base pieces are oversized at their bottom in relation to the grooves, so that the base pieces are secured in the slots when the mounting portion and the tool portion are assembled.

10. A tool according to any one of the preceding claims, characterized in that the tool elements comprise grinding elements for grinding, sanding, polishing or similar work, where the grinding elements may be slotted, while the tool elements preferably also comprise support brushes, which support the grinding elements, wherein the grinding elements and/or the support brushes are fastened in base pieces which are mounted in the grooves in the tool portion. 11. A tool according to any one of the preceding claims, characterized in that the tool rotates about a central axis, for which the edge portion of a number of tool elements is mounted at an angle to the outer surface of the tool portion and/or at an angle to the center axis.

Description:
Tool with tool elements

Field of the invention

The invention concerns a tool with tool elements, preferably grinding and/or sanding elements, which tool is designed for mounting on a machining unit with a motor, which rotates the tool via a drive shaft, which tool comprises a mounting portion and a tool portion, where the tool portion comprises grooves to receive the tool elements, where the mounting portion comprises fastening means for fastening the tool, directly or indirectly, to the drive shaft, wherein the tool elements are secured in the tool portion, after the tool is assembled by connecting the mounting portion and the tool portion.

Background of the invention

The invention has its background in machining units for grinding and sanding, and which are provided for this with a tool in the form of a machining head, such as a grinding head with tool elements in the form of grinding elements. However, the invention may also be employed with other tools, such as polishing disks.

Grinding or sanding tools are known which are provided with grinding elements. Such tools are used extensively within the wood working industry and within the metal working industry. Likewise, the tools may be used within industries for working of other materials, such as fiberglass structures.

For the surface machining of various elements, such as grinding or sanding, it is known how to employ grinding and sanding elements which are mounted on a machining unit in the form of a grinding head. Such a grinding head may be disk- shaped, where the grinding elements are mounted on a side surface of the disk, or constructed as a combination of disk-shaped and cylinder-shaped parts. However, it is typical of these grinding heads that they have some kind of dovetailed groove in which a number of grinding and/or brush elements are mounted. These elements may comprise grinding elements in the form of grinding paper, brushes of fiber, hair, steel or another metal and combinations of these, for example in the form of backstop brushes, which support the grinding paper during use. The grinding paper may be, for example, sandpaper for sanding of wood, metal, and the like, canvas and/or textile for polishing, or leather. Brushes, support brushes and/or backstop brushes may be, for example, steel brushes, plastic brushes, or other types of brushes, including for example brushes of natural materials, such as plant-based brushes or brushes of animal hair.

In the following, these elements will be discussed under a common term as tool elements. Such tool elements can be made of a plastic material, in which grinding paper and brushes are embedded by casting a plastic material around grinding paper and/or brush. Alternatively, brushes and/or grinding paper can be fixed in a rail element by clamping this around the brushes and/or grinding paper, arranged in the rail element used to make the respective tool element, or in another suitable manner.

On a typical grinding head, there are arranged on average between 8 and 50 tool elements. The grinding heads are used often in industrial practice, but the grinding elements need to be replaced regularly. Such a replacement is typically done by pulling them out from the dovetail groove in which they are mounted and replacing them with new tool elements.

The drawback of different types of grinding heads and also accordingly the different types of tool elements for use in these grinding heads is that the different tool elements do not fit in all types of grinding heads. Another very important drawback is the amount of time spent on replacing tool elements due to wear or changing grinding needs.

It is often necessary to acquire several different types of grinding heads and/or tool elements in order to perform different jobs, which naturally involves increased time spent on setting up the tool or the machine on which the grinding head is being used, and a larger investment in grinding heads.

Especially for grinding of profiled workpieces within the lumber industry it is important to have a rotating grinding head with variable speed, which can be used in connection with different kinds of grinding head for grinding, sanding and polishing.

In industrial operations, preferably in the lumber industry, grinding tools are known which have variable speed in the form of pneumatic tools with grinding heads mounted on them. Manual tools are also known with grinding heads driven by electric motor with variable speed.

From DK 177694 Bl there is known a machining unit of the type with a drive shaft, which is connected to a drive plate, on which is secured a tool. The tool is secured by hook and eyelet connectors or bayonet connectors to the drive plate. The tool is thus not secured directly to the drive shaft. In this way, a quick changing of the tool is achieved, especially when using hook and eyelet connectors, either due to wear on the tool or when switching to a different type of tool, and also the same motor unit can be used for different purposes.

The tool has a top plate and a base plate. On the base plate it is possible to mount elements for grinding or sanding. There are furthermore openings in the base plate which make it possible to remove grinding dust through these openings. Top plate and base plate are joined to each other to form the tool, for example by bonding, welding, or mechanical clamping.

The tool is used in handheld tools with motor capacity on the order of 3500 kW. In stationary machining units the motor capacity will be larger. The force of the connection between drive plate and tool will also become larger accordingly in this case. Thus, the hook and eyelet connections between drive plate and tool become too weak, and there is a risk of the tool being pulled off during use.

The assembly of top plate and base plate can also be produced by bonding, welding, or mechanical clamping, for example. These are processes which require a number of work steps with many different tools. Furthermore, they are time-consuming processes requiring some work time to assemble the top plate and base plate. Moreover, both processes are costly. There is hence a desire to achieve alternative ways of producing machining tools for onetime use which are less time-consuming and do not need the use of tools for their assembly, so as to achieve a cheaper product. Purposes of the invention

The purpose of the present invention is to specify a tool where various types of tool elements are mounted on various tools, and when the mentioned tools are easy to change both in order to switch between different tools and to replace the tool when worn out.

Furthermore, the purpose is to specify a tool which is suitable for onetime use and which is a cheap design.

Another purpose is to specify a tool which is suitable for automated assembling or mounting.

Specification of the invention

These purposes are accomplished with a tool of the kind mentioned in the introduction, which is characterized in that the tool portion comprises first mounting means,

the mounting portion comprises second corresponding mounting means for engaging with the first mounting means, and

the first and second mounting means comprise one or more resilient tabs, each of which is provided with at least one barb, and the mounting means furthermore comprise one or more recesses for receiving said barbs with a snap action in the assembled state of the tool for locking of the tool portion and the mounting portion to each other with the tool elements secured in the grooves.

By having first mounting means in the tool portion and second mounting means in the mounting portion one accomplishes a quick assembling of the tool. The tool can be assembled without the use of tools or other equipment. It can be snapped together in easy fashion. One thus achieves a product which is cheap to produce. Furthermore, one achieves a tool which is particularly well suited for onetime use. Thus, it is no longer necessary for the user or operator of the machining unit to mount or keep track of various tool elements for the tool. Instead, the user may simply select a tool or a number of tools with the desired properties for grinding, sanding or polishing a workpiece and mount them on or in the machining unit.

In the tool, the tool elements will be firmly mounted in the tool portion. Thus, there is no intent to be able to replace individual tool elements, such as is often the case in tools known thus far. When the tool elements are worn out, the user will quite simply replace the entire tool. In other words, one may say that one works with disposable tools in the invention.

By employing a tool with fast mounting and dismounting of the entire tool, it is possible to employ many tools in a machining unit that are mutually replaced depending on the machining operations being carried out. The different tools fit like modular elements in the machining unit.

The first mounting means are preferably resilient tabs placed on the tool portion. The second mounting means are preferably recesses placed in the mounting portion. The recesses are preferably placed and configured to receive the resilient tabs such that the locking tabs enter into a locking engagement in the recesses.

Alternatively, the first mounting means are preferably formed as resilient tabs placed on the mounting portion. The second mounting means, preferably recesses, as mentioned above, are placed in this variant in the tool portion.

The resilient tabs and the corresponding recesses are placed such that the tool portion and the mounting portion may only be assembled correctly. A correct assembly can occur in one or more ways. In order to achieve a locking of the mounting portion and the tool portion to each other, there is at least one set of mounting means in the form of resilient tabs with at least one corresponding recess on the mounting portion or the tool portion, respectively. The number of resilient tabs and corresponding recesses is therefore alternatively two, three, four, five, six, seven, eight or more. There should be at least as many recesses in the second part of the tool as there are resilient tabs on the first part of the tool. The number of recesses may also be larger than the number of resilient tabs.

A correct way of assembling the unit may be accomplished, for example, in that the resilient tabs have different mutual spacings around the first inner wall of the tool element, and thus the resilient tabs have an asymmetrical placement. This is especially relevant when the tool is not symmetrical, so that it is important to assemble the tool portion and the mounting portion properly with a fixed position relative to each other.

The resilient tabs may also be placed so as to achieve a rotational symmetry, such that the tool portion and mounting portion can be assembled, for example, in two or more ways, by rotating the tool portion and mounting portion in relation to each other. This is achieved in that the resilient tabs are preferably placed such that they are aligned with the recesses when the tool portion is rotated in relation to the mounting portion. This may also be accomplished by having more recesses than resilient tabs, so that the recesses are placed in correspondence with the resilient elements in the predetermined number of ways in which the tool portion and the mounting portion can be assembled.

In addition to the resilient tabs, one may employ bonding or ultrasound welding for the mutual fastening.

The tool is preferably designed such that the tool portion has a first inner wall, which is directed toward the mounting portion, the mounting portion has a second inner wall, which is directed toward the tool portion, and the radial outer surface of the second inner wall is dimensioned such as to be enclosed by the first inner wall when the tool is in the assembled state, and in connection with the first inner cylindrical wall or in openings in the first wall there are arranged resilient tabs with barbs, and along the radial outer side of the second inner wall in the mounting portion there are arranged a number of recesses in the bottom of the mounting portion, corresponding in position, shape, and number to the tool portion's resilient tabs. The number of recesses need not necessarily correspond to the number of tabs. There may be more recesses, so that there are more possibilities for locking.

The first inner wall on the tool portion and the second inner wall on the mounting portion are able to ensure the stability of the machining unit by supporting the inner portion of the two portions, such that the tool portion cannot be pressed into the mounting portion in event of too much pressure against objects being machined. Having both a first inner wall on the tool portion and a second inner wall on the mounting portion, where the first inner wall on the tool portion encloses the second inner wall on the mounting portion, enables an easy and correct assembly of the tool by ensuring correct positioning of the tool portion and mounting portion in relation to each other and in relation to the drive shaft's position. This also helps achieve a further price reduction in the manufacture of the tool.

Moreover, the first inner wall and the second inner wall, when the first wall encloses the second wall, help reduce the risk of the tool portion and the mounting portion shifting in relation to each other during use. This may occur, for example, if one or more of the resilient tabs should break off. This increases the safety during use of the tool. The first inner wall and the second inner wall preferably have rotational symmetry, such as a cylindrical shape, but they may also have other shapes such as oval, or polygonal, such as triangular, rectangular, pentagonal, hexagonal, or octagonal. This makes it possible to the tool portion and mounting portion to be assembled in two or more ways, as described above.

The first inner wall and the second inner wall may also have any non-rotationally symmetrical form. This means that the tool portion can only be assembled in one way, and this variant means that guide pins with corresponding guide grooves are no longer needed.

The first inner wall and the second inner wall can be an entirely joined wall or they may consist of lesser wall pieces or be an entire wall with openings or wall pieces with openings. The resilient tabs have barbs or hooks preferably at their outer end. Together with the recesses in the mounting portion, this accomplishes a snap lock, which is accordingly easy and quick to assemble. An angular shape helps ensure that the tool portion and the mounting portion are assembled correctly, but other shapes are also possible. The barbs or the hooks on the resilient tabs may face radially outward, radially inward, to the side, or at any angle in between.

The resilient tabs are preferably configured to enter into locking engagement with the mating recesses, so that it is not possible to separate the tool once more. If it is attempted to separate the tool portion and the mounting portion, the resilient tabs are preferably designed to break, so that the tool after separating the mounting portion and tool portion cannot be assembled once more.

The tool can be secured to the drive shaft of a motor both directly and indirectly.

For direct fastening, the tool for example may be secured via a bayonet coupling placed on the inside of the second inner wall of the mounting portion. Alternatively, the tool may be secured to the drive shaft by a thread, for example, wherein the tool is screwed onto the drive shaft, or wherein the drive shaft comprises jaws which grip a shaft which is mounted in the mounting portion.

For indirect fastening to the drive shaft, the tool can be fastened to a drive plate, for example. The drive plate is preferably secured perpendicular to the axis of rotation. The tool is fastened, for example, to the drive plate with hook and eyelet or bayonet couplings. Other forms of indirect fastening of the tool involve an adapter to increase the distance from the motor unit to the tool

Along the periphery of the tool portion there are arranged a number of pins. Furthermore, along the periphery of the mounting portion there is devised a slot, in which the tool portion's pins are designed to engage when assembling the tool in order to secure the periphery of the tool portion to the mounting portion.

As a result, the periphery of the tool portion is secured to the periphery of the mounting portion. This helps ensure the stability of the tool, among other things because the periphery of the tool portion cannot flutter along the periphery of the tool during rotation. This helps ensure that the tool elements cannot fall off when the tool is in use.

Preferably at least one pin is placed between all the grooves, so that all parts of the tool portion are secured in the periphery. The grooves give the tool portion a certain flexibility which helps ensure that the pins can easily be inserted into the slot and thereby help ensure an easy assembling of tool portion and mounting portion. It is also possible to place the pins such that, for example, they are situated in every other or every third space between the grooves. Alternatively, there may be a transposing, or a combination, so that the pins are located along the inner side of the periphery of the mounting portion, and corresponding recesses in the periphery of the tool portion. Alternatively, some pins may be located on the mounting portion, and other pins on the tool portion, with corresponding recesses on the other portion

The slot may be an indentation along the periphery of the mounting portion, but it can also be formed by having a shoulder along the periphery beneath which the pins are secured. The slot may follow the entire periphery all around or be interrupted, so as to create indentations in the mounting portion opposite the corresponding pins.

The slot is preferably arranged in the bottom of the mounting portion or on a radially inner surface of an outer wall, which outer wall is substantially upright along the periphery of the inner bottom of the mounting portion.

This means that it is possible to secure the periphery of the mounting portion and the tool portion to each other, regardless of the configuration of the tool portion and mounting portion. For all embodiments it holds that the slot may be placed either on the mounting portion or the tool portion, and the pins in the corresponding portion.

If the bottom of the tool portion and the bottom of the mounting portion are approximately parallel, one possible solution may be an outer wall along the periphery of the mounting portion. Thus, the slot or the shoulder may be placed on the radial inside of the outer wall. It is also possible to have the tool portion with shapes other than a disk shape. For example, the surface of the tool portion is curved, such as a semicircle, a truncated cone, or a cylinder. In this case, the bottom of the tool portion when assembled with the mounting portion is approximately perpendicular to the bottom of the mounting portion. Hence, the slot or the shoulder may be placed directly in or on the bottom of the mounting portion.

It is possible to place a series of slats along the grooves of the tool portion. The slats are preferably placed in pairs along each side of a groove, including preferably parallel to the grooves. The slats help ensure the spacing between tool portion and mounting portion. This achieves greater stability of the tool. Furthermore, the slats will help secure the position of the tool elements in the tool portion.

The slots for the tool elements may be closed at the periphery of the tool portion, and are formed as openings in the tool portion. In this case, the tool elements are mounted by inserting them from the rear of the tool portion. This is done for the most part perpendicular to the bottom of the tool portion.

The slots may also be formed as slits extending in the tool portion from the periphery of the tool portion. In this case, the tool elements can be shifted into the grooves from the periphery of the tool portion. This provides a faster and easier mounting of the tool elements. The pins along the periphery of the tool portion will ensure that the tool portion, and thus also the tool elements, are fastened in the mounting portion of the tool. Thus, the tool elements cannot shift during use and thereby fall out of the tool. Preferably at least one guide groove is placed in the first inner wall of the tool portion. Likewise, on the mounting portion there is preferably placed at least one guide pin in connection with the second inner wall of the mounting portion, so that the guide pin is designed to engage with the guide groove when assembling the tool portion and the mounting portion.

Alternatively, the placement of guide groove and guide pin is reversed, so that the second inner wall of the mounting portion comprises at least one guide groove, and at least one guide pin is arranged in connection with the first inner wall of the tool portion.

In this way, the tool becomes easier to assemble. Moreover, this ensures that the tool portion cannot be mounted wrong in the mounting portion.

There may be either one or more guide pins and a corresponding number of guide grooves The guide pins may be placed such that tool portion and mounting portion can be assembled in only one or several different ways upon rotation of the tool portion in relation to the mounting portion.

Accordingly, there may be one, two, or several guide pins on the mounting portion, but more guide grooves than guide pins, in the inner wall of the tool portion, all of them corresponding to correct assemblages of tool portion and mounting portion. The bottom of the tool portion may preferably be formed as a disk, a cylinder, a conical shape, or with a curved shape, such as a concave or convex shape.

This ensures that the tool can be adapted to different uses, such as different machines, and different use of machines. For internal grinding, tool portions other than disk shape will be preferred, just as a different configuration of the tool portion may be advantageous for non-flat workpieces undergoing grinding or polishing. For example, a concave configuration of the tool portion may be used for workpieces with spherical surface, and a conical or cylindrical configuration of the tool portion may be used for internal grinding or polishing of hollow workpieces.

The outer periphery of the tool preferably has one of the following shapes: circular, oval or polygonal, such as triangular, rectangular, pentagonal, hexagonal, heptagonal, octagonal, and so on. Different shapes of the tool provide flexibility during use. Often the tool will be circular or polygonal, but in certain cases other forms will be preferred, the choice of the tool shape being adapted to the grinding or polishing job. Tool elements preferably encompass grinding elements for grinding, sanding, polishing or similar work, where the grinding elements may be slotted.

Grinding elements are usual for grinding and slotted grinding elements achieve an improved grinding plane.

The tool preferably rotates about a central axis, for which the edge portion of a number of tool elements is mounted at an angle to the outer surface of the tool portion and/or at an angle to the center axis. The tool elements are preferably mounted with an orientation for the most part perpendicular to the surface of the outer surface of the tool portion. The tool elements are preferably placed radially. The tool elements are placed radially when the angle a (see fig. 5) is approximately perpendicular in relation to the radial direction. Alternatively to an orientation which is substantially perpendicular to the surface, the tool elements can be placed at an angle β which departs from the perpendicular in relation to the surface. Likewise, it will be possible to place the tool elements with an orientation not entirely radial but instead at an angle a in relation to a radial orientation. Thus, the tool elements will have an angle a (see fig. 5) which is not a right angle, but either larger or smaller than a right angle.

With a slanted mounting of the tool elements in relation to the radial position, it becomes possible to change the machining properties of the tool. Accordingly, the tool elements are preferably mounted substantially perpendicular to the surface, where the angle β (see fig. 5) is a right angle in to the surface of the tool elements. But the tool elements can be placed with an angle which is both larger and smaller than a right angle, in which case the tool elements are mounted slanted in the tool.

Such a layout establishes a grinding disk for which the use of slotted grinding bodies is especially suitable for grinding of surface with profilings. The slotted grinding bodies on a surface of a circular disk are in themselves known from previous apparatus where interchangeable tool elements are used.

The tool elements preferably comprise support brushes which support the grinding elements, the grinding elements and/or the support brushes being secured in base pieces which are mounted in the grooves in the tool portion.

This accomplishes an easy mounting of the tool elements in that the tool elements are fastened in the base piece. An especially effective grinding is achieved with the use of support brushes.

Grinding elements and support brushes can also be mounted each in their own base piece, so that the two base pieces engage with each other and thereby constitute a single base piece during use.

Having grinding elements and support brushes each in their own base piece achieves greater flexibility in the choice of which support brushes and grinding elements will work together. When the base pieces from the support brushes and the grinding elements engage, both support brushes and grinding elements are correctly facing each other, and they form a unit when placed together, so that they are easy to install in the grooves. This also means that fewer loose parts need to be stockpiled in order to provide a large selection of tools with different properties. This further reduces the production costs per unit. Low production costs and thus low price to the user mean that the tool is well suited to onetime use.

The tool elements are preferably mounted in base pieces with an oversized bottom in relation to the grooves so that the base pieces are secured in the grooves when the mounting portion and the tool portion are assembled By using base pieces with an oversized bottom in relation to the grooves in the tool portion it is possible to insert the individual tool elements from the rear of the tool portion. After the tool elements are inserted in the grooves, the tool portion and mounting portion are assembled with the bottom of the base pieces placed between the tool portion and the mounting portion. Thus, the bottom of the mounting portion will press the base pieces into firm engagement in the mounting openings.

The tool elements will then protrude from the outer top side of the tool portion. The tool can be swapped for a corresponding tool in event of wear or with a different type of machining unit when different jobs need to be undertaken in continuation of each other.

Thus, with the tool according to the invention it becomes possible for a user to employ the same motor unit for different tools, which can easily be interchanged without the use of tools. The motor unit may be a pneumatic variable speed motor or an electric motor. The motor unit may be either small handheld units or large industrial machines, for example, with throughput of workpieces being ground or polished. According to another embodiment, the tool according to the present invention is characterized in that the tool elements of the tool comprise means of grinding, sanding, polishing and/or similar work.

As mentioned above, a tool according to the present invention will primarily find use in grinding and polishing jobs. Therefore, the tool elements will be means which are used for grinding, sanding, polishing or similar jobs. Such tool elements may be chosen with a layout which is known in itself from the previously mentioned industrial machines with interchangeable tool elements. During use, the tool will preferably rotate about a central axis coinciding with the motor unit's drive shaft.

The tool will preferably be a circular disk. Alternatively, one can use disks having an angular or other shape. The disk used will preferably rotate about a central axis. This results in a tool with rotational symmetry. On the circular disk there is a flat surface, on which a disk-shaped grinding element or alternatively a polishing element can be mounted.

When using the tool, therefore, there will be a grinding with a tool whose tool elements have a flat or approximately flat surface, including for example a disk with a slightly truncated conical surface. The tool element may be on a soft and yielding backing in the tool so as to adapt to different surface contours during the grinding.

With a common central axis for the tool and the drive shaft one achieves a simple construction of the grinding tool, and there is no risk of damaging effects occurring from shaking and vibrations, which is known for example from off-center grinders.

We shall now give a closer explanation of special tool elements in the form of slotted grinding paper for use in the tool. The grinding element's slats are formed by slitting a grinding paper transversely to the longitudinal direction, so as to produce ribbons or slats, being mutually joined together at one end by means of an unbroken strip of grinding paper which is fastened in the base piece. Thus, the free end consists of a number of parallel slats of grinding paper which extend for the most part perpendicular to the longitudinal direction of the profile. In a plane parallel with the grinding slats, support brushes will be placed in immediate proximity to the slats, so that they support the slats during the grinding.

The grinding or sanding effect is achieved as a consequence of the action of the slats when they sweep over a workpiece during the rotation of the tool. The support brushes have, as the word implies, a function of supporting the grinding slats. However, the support brushes may also be made of a material so as to contribute to the grinding or sanding effect. The support brushes are placed slightly behind the grinding bodies, so that they support the grinding bodies and thereby hold the grinding portion of the grinding bodies in against the surface being ground.

The support brushes furthermore ensure that the grinding bodies will never bend around the base or lay back across the surface of the grinding disk. It is an advantage that there is a certain distance from the surface of the grinding disk down to the surface being ground, so that ground-off material can be taken away and to reduce the risk that the surface of the grinding disk will come in contact with the ground-off surface. The number of rows of support brushes may vary, depending on how much support the grinding bodies will have. This means that, for example, there may be three rows of support brushes behind each of the grinding bodies.

Since the grinding bodies are mounted for the most part perpendicular to the disk surface, it is possible to make better use of the grinding portion of the grinding bodies than in the case of grinding paper bodies which are placed with a large overlap, as is known. Thus, a grinding disk according to the present invention has a longer lifetime than the commonly known flat or ring-shaped grinding disks.

Instead of mounting the grinding bodies so that they have a radial extension over the majority of the surface radius, the grinding bodies can be mounted in a backward curved arrangement with respect to the direction of rotation.

Description of figures

The invention will now be described with reference to the drawings, where

Fig. 1 shows a tool according to the invention in perspective,

Fig. 2 shows a possible tool element for use in the tool according to the invention,

Fig. 3 shows a tool according to the invention in perspective from opposite angle, Fig. 4 shows the outer surface of the tool portion,

Fig. 5 shows the inner surface of the tool portion,

Fig. 6 shows the first inner wall of the tool portion with resilient tabs with barbs and guide grooves, and Fig. 7 shows the mounting portion with guide grooves and recesses for locking the tool portion's resilient tabs.

Detailed description of the invention

The invention is described with regard to a circular embodiment of the tool, but the tool may also have different configuration, as described above.

Fig. 1 shows a tool 1 for machining of wood, metal or composite materials, for example. The tool 1 consists of a tool portion 2 and a mounting portion 3, which are joined together so that they secure a number of tool elements 4. Furthermore, the mounting portion 3 is configured to be fastened directly to a drive shaft 5 on a motor unit (not shown in fig. 1).

Fig. 3 shows a tool 1 from a different angle. Here, one sees the mounting portion 3, which is joined by a bayonet coupling 6 to the drive shaft 5.

Fig. 4 shows the outer side of the tool portion, on which there are grooves 7 for tool elements 4. Fig. 5 shows the inner side of the tool portion. On the tool portion's inner bottom 8 is placed a first inner wall 9. In fig. 5, the first inner wall 9 is circular. The first inner wall 9 may have other shapes, as described above. In the first inner wall 9 there are formed a series of openings, there being 6 openings in the figures. In four of the openings there are arranged a resilient tab 10. The last two openings are guide grooves 11. As mentioned above, it is possible to have more or fewer guide grooves, and it is likewise possible to employ fewer or more resilient tabs.

Fig. 5 furthermore shows a series of slats 12, which lie parallel with the grooves 7 for the tool elements. In this way, a slit is formed for fastening the tool elements 4.

Along the tool portion's periphery 13 there is arranged a series of pins 14. In figure 5 one pin 14 is placed between each groove 7 for fastening of the tool portion's periphery 13 to the mounting portion 3. It is possible to have more or fewer pins. Fig. 6 shows an enlargement of the inside of the tool portion. One sees here the resilient tabs 10 secured to the bottom of the tool portion 8. As emerges from the drawing, the surface of the resilient tab 10 is shifted slightly radially inward from the first inner wall 9, yet always such that it remains in connection with the openings. At the top of the resilient tab there is arranged a barb or hook 15, which forms the male part in a snap lock when assembling the mounting portion 3 and tool portion 2. The first inner wall 9 is cylindrical, but it can have other forms, as described above.

Fig. 7 shows the interior of the mounting portion 3. On the mounting portion's bottom 16 there is a second inner wall 17. The second inner wall 17 is cylindrical, but may also have other forms, as described above. Along the inner wall 17 there is a series of recesses 18, adapted in position to the tool portion's 2 resilient tabs 10 (see fig. 6.), and such that the recesses 18 constitute the female part in the snap lock when assembling the tool portion and the mounting portion.

In connection with the mounting portion's 3 second inner cylindrical wall 17 there is preferably placed guide pins 19. The guide pins are secured to the bottom 16 of the mounting portion 3 and to the mounting portion's second inner wall 17. The guide pins 19 extend preferably radially outward from the mounting portion's inner wall 17. The guide pins 19 are placed so that they engage with the guide grooves 1 1 on the tool portion 2 when the mounting portion 3 and tool portion 2 are correctly assembled. If one tries to assemble the mounting portion 3 and tool portion 2 in an incorrect manner, the guide pins will abut against the tool portion's first inner wall 9 and prevent the mounting portion 3 and the tool portion 2 from being assembled.

Along the periphery of the mounting portion 3 is placed an outer wall 20, which is directed toward the tool portion. Along the upper edge of the outer wall 20 is placed a slot 21 on the radially inner side of the outer wall 20. The slot 21 is placed such that the pins 14 of the tool portion (see fig. 6) fit into the slot, whereupon the periphery of the tool portion 2 is locked firmly to the periphery of the mounting portion 3.

The grooves 7 on the tool portion 2 for fastening of the tool elements 4 are preferably configured as slits from the periphery of the tool portion. In this way, it is possible to change the tool elements in place from the periphery of the tool portion.

Alternatively, the grooves 7 are closed at the periphery and the tool elements 4 are mounted in the tool portion 2 by leading them out through the grooves 7 from the rear of the tool portion.

On the inner side of the second inner wall 17 of the mounting portion there is devised for example a bayonet socket 6 for fastening of the tool 1 to the drive shaft 5. It is also possible to mount the tool 1 on the drive shaft of the machining unit by other means, as described above.

Fig. 2 shows an example of a tool element 4 which consists of a base piece 23, in which is placed a brush 24 and a grinding or polishing element 25. Figure references:

1. Tool

2. Tool portion

3. Mounting portion

4. Tool element

5. Drive shaft

6. Bayonet socket

7. Groove

8. Bottom of tool portion

9. First inner wall

10. Resilient tab

11. Guide groove

12. Slats

13. Tool portion's periphery

14. Pin on periphery

15. Barbs

16. Mounting portion's bottom

17. Second inner wall

18. Recesses 19. Guide pin

20. Mounting portion's outer wall

21. Slot in periphery

22. Bayonet coupling

23. Base piece for brushes and/or grinding element

24. Brushes

25. Grinding element