Surface Processing Tool and Surface Processing Machine Equipped Therewith

Description

BACKGROUND

The disclosure relates to a surface treatment tool comprising an annular carrier substrate and a plurality of abrasive lamellae connected to the carrier substrate with a narrow side in a contacting juxtaposition of their flat sides, at least some of which are fiber fleece lamellae. The disclosure further relates to a surface treatment machine which is equipped with such a surface treatment tool.

Such surface treatment tools include, for example, tools used to treat surfaces by means of brushes. Such tools are used to create a certain surface appearance on the surface of a workpiece, for example a metal workpiece. This can be a typical appearance of a brushed surface as well as a satin or matting finish. Workpieces are also brushed to remove burrs, round corners or remove dirt. With the exception of rounding corners or edges or removing burrs remaining on the workpiece as a result of previous processes, such as a previous punching process, such brushing is ultimately carried out without changing the dimensions of the workpiece. This distinguishes the process of brushing from the process of grinding as a material-removing machining process with an indeterminate cutting edge.

Such surface treatment tools have an annular carrier substrate. These previously known surface treatment tools are a rigid support tube or a corresponding support tube section, depending on the required length of such a surface treatment tool. Longer surface treatment tools of this type are referred to as brush rollers. The carrier substrate, which is rigid in terms of its shape and therefore not flexible, is clamped between two clamping flanges sitting on a drive shaft with which the surface treatment tool is set in rotation for its use. The surface of this carrier substrate, which faces outwards in a radial direction, carries a large number of abrasive fiber fleece lamellae. The fiber fleece lamellae are connected to the carrier substrate with a hard adhesive bond with a narrow side following the axis of rotation. Neighboring fiber fleece lamellae can contact each other at their flat sides facing each other. If adjacent fiber fleece lamellae do not come into direct contact with each other, a layer of abrasive cloth or a similar material is inserted between them. Surface treatment tools with an annular carrier substrate made of a rigid material cannot be used for belt machines.

From WO 2010/058289 A2 a surface treatment machine with an annular surface treatment tool is known, in which the surface treatment tool is designed as a belt. This surface treatment tool is designed as a polishing tool. This comprises a flexible belt as a carrier substrate, on the outside of which a flexible abrasive fiber fleece mat is applied. The preferred thickness of the fleece mat is indicated as 15 mm. Incisions are made in this mat transverse to the direction of belt travel in order to achieve the necessary flexibility so that the flexible belt with the fleece mat attached to it can be deflected on deflection rollers. This flexible mat can be a nylon fiber fleece that is impregnated with a synthetic resin-abrasive grain mixture. With this previously known surface treatment tool, the material thickness of the fiber fleece available for processing is limited by the thickness of the mat. Due to the limited thickness of such fleece mats, the service life of such a surface treatment tool is quite short. Furthermore, with this surface treatment tool, the belt sections guided over deflection rollers cannot be used for the process of brushing the surface of a workpiece, since the incisions in these sections to achieve the necessary elasticity for the deflection result in the formation of gaps in the peripheral surface. The surface treatment is difficult to control due to the spaced apart fleece segments. Furthermore, if the surface treatment tool is used in positions where it is guided over a deflection roller, the wear of the fiber fleece would be significantly increased. This would also significantly reduce the service life of such a surface treatment tool.

In another embodiment of a surface treatment tool with an annular belt, a circulating belt serves as the carrier substrate, on the outside of which base bodies are arranged. These respectively carry a treatment element. Such surface treatment tools are known, for example, from DE 10 2014 115 778 A1 and DE 10 2015 110 115 A1. This surface treatment tool has the same disadvantages as the one according to WO 2010/058289 A2.

SUMMARY

Proceeding from this background, an aspect of the disclosure is to propose a surface treatment tool, which is particularly suitable for brushing surfaces, that is not only easier to manufacture, but also has a longer service life.

This is achieved by a surface treatment tool of the type mentioned at the outset, in which the carrier substrate is a flexible belt, the ends of which pointing in the longitudinal extension of the belt are connected to one another to form an annular shape, and in which the fiber fleece lamellae are connected to the outward-facing surface of the flexible belt in a state in which they are elastically compressed with respect to their thickness by means of an adhesive connection with flexible material properties.

This surface treatment tool provides for the fiber fleece lamellae to be connected to the flexible belt as a carrier substrate in an elastically compressed state with respect to their thickness. If abrasive layers or corresponding layers are arranged between the fleece fiber lamellae, these are located between the individual fleece fiber lamellae. These have no influence on the compression. Abrasive cloth or similar material can be inserted between each fleece lamella or only between two fiber fleece lamella segments, comprising, for example, two, three or even more fiber fleece lamellae. The connection of the lamellae, in particular the fiber fleece lamellae, is achieved by means of an adhesive bond with flexible, typically permanently elastic material properties, i.e. with an adhesive which remains flexible after it has hardened or after the cross-linking process has been completed. The compression of the fiber fleece lamellae takes place in the thickness direction, with the fiber fleece lamellae typically being connected to the belt with their narrow side in a transverse direction to the belt running direction. Thus, the compression of the fiber fleece lamellae acts transversely to the plane of their flat sides. In this respect, the elastic properties of such an abrasive fiber fleece are cleverly used so that, in the case of a curved belt path, for example when the belt runs around a deflection roller, adjacently arranged fiber fleece lamellae contact each other with their flat sides in the radial direction, preferably over their entire radial extension. A gap formation that occurs in the prior art due to the belt curvature is therefore avoided with this surface treatment tool, at least with a normal belt curvature. Therefore, such a belt tool can also be used if it has a curved course in sections, such as on a deflection roller of a belt machine, or if the surface treatment tool is designed to be clamped on an expansion roller and thus has an overall curved peripheral surface. The service life of such a surface treatment tool can also be significantly longer than that which is possible with the surface treatment tool according to WO 2010/058289 A2, because the height of the fleece lamellae, and thus their extension from the outside of the flexible belt to the treatment surface, which is provided for each fleece lamella by the radially outer narrow side of such a lamella, does not depend on the mat thickness from which the fleece lamella is cut. Rather, the height of such a fiber fleece lamella can be tailored to the desired requirements. Therefore, there is significantly greater design freedom when it comes to manufacturing such a surface treatment tool.

The design of the surface treatment tool with a flexible belt as a carrier substrate also has a positive impact on the CO2 footprint of the companies using such surface treatment tools. Compared to surface treatment tools with a rigid core, a surface treatment tool according to the disclosure can be packed by utilizing its radially flexible properties and by utilizing the volume enclosed by the carrier substrate, so that the cavity present in rigid carrier substrates can be used at least to the greatest extent for the packaging and transport of such a surface treatment tool and thus for a particularly compact package. In addition, the weight of a carrier substrate designed as a flexible belt is significantly lower than that of a rigid annular carrier substrate. This also has a positive effect on the CO2 footprint, especially in connection with the transport of such surface treatment tools.

While in a generic surface treatment tool the abrasive fiber fleece lamellae must be mounted on the curved surface of the annular rigid carrier substrate, in the surface treatment tool according to the disclosure the flexible belt serving as the carrier substrate can be fitted or equipped with the fiber fleece lamellae before this belt is brought into its annular shape. This allows the carrier substrate to be assembled on a flat surface. This simplifies the manufacturing process considerably.

Investigations have shown that the service life of a surface treatment tool according to the disclosure is significantly longer than that of a conventional surface treatment tool with a fleece fiber mat connected by its flat extension to a flexible belt as a carrier substrate, due to the fact that the radial extension of the fleece fiber lamella is significantly greater than the thickness of a fleece fiber mat used in the prior art. The service life of such a surface treatment tool is also improved compared to those with a rigid carrier tube as the carrier substrate if the surface treatment tool is clamped onto an expansion roller that is flexible in the radial direction as a rotary drive.

According to a preferred embodiment of such a surface treatment tool, the longitudinally pointing ends of the belt are arranged abutting against each other and connected to each other. In some applications, it has proven to be useful if these ends are provided by a bevel cut of the belt, for example with an inclination of 75 or 80 degrees to form the annular shape of the cutting line compared to the course of the long sides or the direction of travel of the belt. The ends of the flexible belt pointing in the longitudinal direction can of course also be designed without a bevel cut. The longitudinal ends of the flexible belt do not necessarily have to be joined together end to end. It is quite possible to mill the sides of the flexible belt facing each other to half their thickness and to glue the ends together in a stacked arrangement.

The degree of compression of the abrasive fleece lamellae is typically between 20% and 85%, i.e. the original thickness of the fiber fleece lamellae cut from a fleece mat has been reduced by at least 20%. The degree of compression depends on the curvature around which the surface treatment tool is guided or, if mounted on an expansion roller, its outer peripheral surface. Furthermore, the degree of compression will be designed depending on the desired purpose of the surface treatment tool. In a preferred embodiment, the compression ratio is at least 30% to 55%. Even higher levels of compression are possible. Preferably, the fiber fleece lamellae are only compressed to such an extent that a certain compression buffer remains unused in the compression direction. Although block compression is possible, it is generally not the goal.

The abrasive fiber fleece lamellae are made of polymer fibers. A nylon fiber fleece is particularly suitable. Such a fiber fleece obtains its abrasive properties through being equipped with a synthetic resin-abrasive grain mixture. For this purpose, the nylon fiber fleece can be soaked or sprayed with the synthetic resin-abrasive grain mixture. The nylon fiber fleece is open. This means that as a result of the impregnation process, the synthetic resin-abrasive grain mixture wets the fiber fleece or fiber fleece mat through and through. The synthetic resin is flexible after polymerization and can also exhibit elastic properties. The elastic restoring force built into the fiber fleece lamellae by compression results from the elasticity of the fibers used, for example nylon fibers, possibly supplemented by the elasticity of the synthetic resin containing the abrasive grains and coating the fibers.

It is preferably provided that the fiber fleece lamellae applied to the flexible belt have a linear extension transverse to the belt running direction. This means that their course, essentially perpendicular to the machining direction, is straight.

However, a non-linear extension is also conceivable, for example a curved, wave-shaped extension or one composed of a plurality of sections adjacent to one another at an angle. In this way, the brushing properties can be adjusted.

In a first embodiment of such a surface treatment tool, it is designed to be mounted on a belt machine. Such a surface treatment machine thus has at least two deflection rollers arranged at a distance from one another in the direction of belt travel, of which at least one is driven. The surface treatment tool is guided over the deflection rollers. The entire circumferential surface can be used for brushing a workpiece.

According to a second embodiment, the annular surface treatment tool is designed to be connected to or clamped onto an expansion roller. Such an expansion roller engages in the ring body of the surface treatment tool and clamps it in the radial direction during use due to the resulting centrifugal force. The outer surface of such a surface treatment tool that can be used for surface treatment is then cylindrical. In a preferred design of such a surface treatment machine, it is provided that the expansion roller is elastic in the radial direction or has a certain elasticity. This can be set up with an appropriate design of the expansion roller. Such adjustability of the radial elasticity of such an expansion roller can be achieved, for example, by the expansion roller having a plurality of reinforcing element holders distributed over its circumference. These can be open in the radial direction. Such reinforcement element holders can also be open at the front and into which rod-shaped reinforcement elements can be inserted. Depending on the elasticity to be set for a specific application, one or more reinforcing elements are then inserted into each reinforcing element holder. These can differ from one another in terms of their reinforcement functionality, so that the elasticity of the expansion roller in the radial direction can also be influenced by the selection of the use of the respective reinforcement element. The elasticity acting in the radial direction can also be achieved by an expansion roller, the interior of which can be actuated pneumatically or hydraulically. As a result, the diameter of the outer surface of the clamping section of the expansion roller can be increased for positioning a surface treatment tool, whereby at the same time the surface treatment tool can be clamped on the expansion roller. At the same time, the elasticity inherent in the expansion roller is adjusted.

Such elasticity in the radial direction has the advantage that the flexibility of the tool desired during brushing does not only have to be provided by the abrasive fiber fleece lamellae, but also by the elastic flexibility of the expansion roller. This also contributes significantly to a longer service life of the fiber fleece lamellae and thus of the surface treatment tool. Since flexibility is still present with such a design of the surface treatment machine even when the fiber fleece lamellae are largely worn out, the surface treatment result is also much more homogeneous over the service life of such a surface treatment tool.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description is provided using an example embodiment with reference to the appended figures, wherein:

FIG. 1 shows a sectional view of a mechanical brush tool as an example embodiment of a surface treatment tool,

FIG. 2 shows a schematic representation of a first manufacturing step for manufacturing the surface treatment tool of FIG. 1,

FIG. 3 shows a schematic representation of a second manufacturing step for manufacturing the surface treatment tool of FIG. 1, and

FIG. 4 shows a schematic representation of a further manufacturing step for manufacturing the surface treatment tool of FIG. 1.

DETAILED DESCRIPTION

A mechanical or industrial brushing tool as a surface treatment tool 1 has a flexible belt 2 as a carrier substrate. The flexible belt 2 is tension-proof in the circumferential and transverse directions and flexible in the radial direction. The flexible belt 2 is formed from a flexible belt strip, the longitudinally extending ends of which abut one another with a bevel cut and are held together by means of an adhesive strip 3. The adhesive strip 3 does not necessarily serve solely to ensure that the flexible belt 2 remains in its closed annular shape.

A plurality of abrasive fiber fleece lamellae 4 are attached to the surface of the flexible belt facing outwards in the radial direction. These fleece lamellae 4 are sections of a fleece mat. The fiber fleece lamellae 4 are connected to the flexible belt 2 by means of a permanently elastic adhesive 5 with a narrow side 6 following the longitudinal axis of the ring shape of the flexible belt 2. Due to the bevel cut of the ends pointing in the longitudinal extension of the flexible belt 2 and the axial alignment of the fleece lamellae 4 connected on the outside, the end sections of the flexible belt 2 are also connected to one another via the adhesive 5 and the fleece lamellae 4 adhesively connected to them, which overlap the joint of the ends of the flexible belt 2. For the sake of clarity, only some fiber fleece lamellae 4 are shown in FIG. 1. These are arranged, as indicated by dash-dotted lines, over the entire circumference of the flexible belt 2.

The fiber fleece lamellae 4 of the illustrated embodiment are open nylon fiber fleece lamellae which have been impregnated with a plastic-resin-abrasive grain mixture. In addition to its function of fixing the abrasive grains, the synthetic resin component also serves to stabilize the structure of the fleece. Such fiber fleece mats from which the fiber fleece lamellae 4 are cut are sufficiently known and therefore do not require any more detailed discussion in the context of this disclosure. For the purposes of the surface treatment tool 1, the elastic properties of such a fiber fleece mat or of the fiber fleece lamellae 4 cut therefrom are used. In the embodiment shown, the fiber fleece lamellae 4 are designed with regard to their plastic-abrasive grain mixture content so that the surface treatment tool 1 can be used for brushing a surface of a workpiece.

It can be seen from FIG. 1 that the fiber fleece lamellae 4 in the cross section shown have a trapezoidal contour geometry, wherein the flat sides 7 of adjacent fleece lamellae 4 abut against one another and thus contact one another, namely over the entire radial extension.

The fiber fleece lamellae 4 arranged on the outside of the flexible belt 2 are compressed in the direction of rotation of the flexible belt 2 (indicated by an arrow in FIG. 1) and in this way brought into the trapezoidal cross-sectional shape shown in FIG. 4 1. A special feature of this surface treatment tool 1 is that there are no gaps between adjacent fiber fleece lamellae 4 on the peripheral surface 8 of the surface treatment tool 1. In the embodiment shown in FIG. 1, the surface treatment tool 1 is a brush disk with an axial extension of approximately 5 cm. To use the surface treatment tool 1, it is clamped onto an expansion roller that is inserted into the opening of the flexible belt 2. This allows the surface treatment tool 1 to be driven in the direction of rotation shown in FIG. 1 or in the opposite direction of rotation.

In an embodiment variant not shown in the figures, the carrier substrate provided by a flexible belt is designed to be significantly longer than the flexible belt 2 of the surface treatment tool 1 of FIG. 1. This surface treatment tool is intended to equip a belt brushing machine. The surface treatment tool is then guided over two or more deflection rollers. At the deflection rollers, the fiber fleece lamellae have the cross-sectional geometry shown in FIG. 1. On the straight belt sections located between the deflection rollers, the fiber fleece lamellae are also compressed on their outward-facing peripheral surface to the same extent as at the connection of their narrow sides to the flexible belt. Thus, when the surface treatment tool is used, these fleece lamellae “breathe” in the transition from a straight section to a curved section guided around a deflection roller, without a gap being formed between adjacent fiber fleece lamellae on the peripheral surface in the area of a deflection around a deflection roller in a belt brushing machine. This breathing has a positive effect on the surface treatment process, as it leads the resulting abrasion away from the peripheral surface.

The surface treatment tool 1 of the illustrated embodiment can be manufactured using the processing steps shown schematically in FIGS. 2 to 4. In a first step, the flexible belt 2 is prepared and placed on a flat base surface (not shown). In addition, the fiber fleece lamellae 4 required for equipping the flexible belt 2 are provided, namely cut from or cut out of an abrasive fiber fleece mat. The individual fiber fleece lamellae 4 are positioned with their flat sides 7 adjacent to one another in the number required to equip the flexible belt 2, so that their narrow side 6 faces the intended outer side of the flexible belt 2. The original thickness of the fiber fleece lamellae 4 visible in this figure corresponds to the thickness of the fleece mat from which the fleece lamellae 4 are cut out. Depending on the intended design of the surface treatment tool 1, the flexible fiber fleece lamellae 4 can be cut from a fiber fleece mat with a larger or smaller thickness. Typical thicknesses of such fiber fleece mats are 3 to 30 mm. The height of the fiber fleece lamellae 4 can also influence the properties of the surface treatment tool 1.

In a subsequent step, the fiber fleece lamellae 4 are compressed transversely to the plane of their flat sides 7, as shown in FIG. 3. In the illustrated embodiment, the compression which occurs is approximately 35%. This degree of compression corresponds to the degree of compression exhibited by the narrow sides 6 of the fiber fleece lamellae 4 on the outside of the flexible belt 2 of FIG. 1. The compression of the fiber fleece lamellae 4 can, as indicated in FIG. 3 by the block arrows, take place between two compression plates which are moved towards each other to compress the fiber fleece lamellae 4. In addition, such compression plates hold the fiber fleece lamella stack enclosed by them between the compression plates and it can be positioned on the upper side of the flexible belt 2. Before positioning such a fiber fleece lamella stack on the flexible belt 2, the adhesive 5 is applied to the flexible belt 2. This can be applied over the entire outer side of the flexible belt 2. In another embodiment, it is provided that this is applied in multiple adhesive beads following the longitudinal extension of the flexible belt 2. As shown in FIG. 4, the fiber fleece lamella stack formed from the compressed fiber fleece lamellae 4 is immersed in the not yet cured or cross-linked adhesive 5 and held in this position until the adhesive 5 has cured to such an extent that the compression in the region of the narrow sides 6 of the fiber fleece lamellae 4 is permanently maintained.

In a subsequent step, the flexible belt 2 is formed into the ring body shown in FIG. 1 and the ends, which are made with an oblique cut 9 and point in the longitudinal direction, are connected to one another by the adhesive belt 3. The gap then located between the respective last fiber fleece lamellae 4 is filled by inserting further compressed fiber fleece lamellae 4. For this purpose, this outer ring section of the flexible belt 2 is previously coated again with adhesive 5. If the adhesive 5 is applied as adhesive beads that follow the longitudinal extension of the flexible belt 2 and are spaced apart from one another, fresh adhesive beads can be applied in the spaces between the adhesive beads for this last step, which then serve to provide the required hold for the last-mounted fiber fleece lamellae 4.

In a preferred embodiment of a use of the surface treatment tool 1 shown in FIG. 1, the tool is clamped onto an expansion roller which has a certain elastic flexibility in the radial direction. This has the advantage that a pressure acting in the radial direction on the peripheral surface 8 when using the surface treatment tool 1 does not have to be compensated for by the fiber fleece lamellae 4 alone, but can also be absorbed by the elastic flexibility in the radial direction of the expansion roller. For finishing a workpiece with the surface treatment tool 1 on its peripheral surface 8, a certain treatment pressure is required. Since this is partly absorbed by the elastic restoring force of the expansion roller carrying the surface treatment tool 1, the fiber fleece lamellae 4 are elastically stressed to a lesser extent in the radial direction. This has a positive effect with a considerable extension of the service life of the surface treatment tool 1.

In the surface treatment tool 1, the degree of compression of its fiber fleece lamellae 4 can be determined retrospectively in two different ways:

In a first possibility, in a first step a fiber fleece lamella 4 is removed from the flexible belt 2. The gap thus created between the fiber fleece lamellae 4 surrounding the removed fiber fleece lamella 4 will be closed over time due to the relaxation force stored in the surrounding fiber fleece lamellae 4; the fiber fleece lamellae 4 immediately adjacent to the gap are partially pressed into the gap by fiber fleece lamellae 4 further away from the gap, and partially expand directly into the gap. The verification according to this first possibility is therefore carried out on the surface treatment tool 1.

In a second possibility, in a first step a fiber fleece lamella 4 is also removed from the flexible belt 2. It is to be ascertained that there are no adhesive residues on the adhesive side. Due to the restoring force stored in the fleece lamella 4 acting in the transverse direction to its flat side 7, this fleece lamella 4 automatically returns to its original thickness. The detection according to this second possibility is therefore carried out on the fiber fleece lamella 4 removed from the surface treatment tool 1.

The recovery due to relaxation, which is used to detect the previous compression according to the two options, may take some time. To accelerate this process, a noticeable dimensional change can be carried out under the influence of temperature, for example in an oven at 80 to 130° C.

The invention has been described in the context of example embodiments. Without departing from the scope of the claims, there are numerous other designs for a person skilled in the art to implement the invention without these having to be shown or explained in more detail in the context of this disclosure.

LIST OF REFERENCE NUMERALS

• • 1 surface treatment tool
  • 2 flexible belt
  • 3 adhesive strip
  • 4 fiber fleece lamella
  • 5 adhesive
  • 6 narrow side
  • 7 flat side
  • 8 peripheral surface
  • 9 bevel cut