Grinding machine for grinding a surface of an object

Abstract

The invention relates to a grinding machine for grinding a surface of an object, comprising at least one grinding tool with a movable abrasive carrier, and a plurality of abrasive elements attached to the abrasive carrier, and an abrasive drive device for driving the grinding tool into a first relative movement to the object, and a conveying device for conveying the object through the grinding machine with a second relative movement to the grinding tool.The invention is characterized in that the plurality of abrasive elements has a plurality of first surfaces provided with first abrasive bodies for contact with the surface of the object during a first direction of movement of the abrasive carrier and a plurality of second surfaces provided with second abrasive bodies for contact with the surface of the object during a second direction of movement of the abrasive carrier opposite to the first, and that the abrasive drive device is designed to be operated in the first direction of movement, in which the first surfaces of the abrasive elements are in grinding engagement with the surface of the object and in the second direction of movement, in which the second surfaces of the abrasive elements are in grinding engagement with the surface of the object.

Description

[0001] The invention relates to a grinding machine for grinding the surface of an object, comprising at least one grinding tool with a movably mounted abrasive carrier and a plurality of abrasive elements attached to the abrasive carrier, and an abrasive drive device for driving the grinding tool in a first relative movement to the object, and a conveying device for conveying the object through the grinding machine in a second relative movement to the grinding tool. A further aspect of the invention is a grinding tool for grinding the surface of an object and a method for grinding the surface of an object.

[0002] Grinding machines and tools are used to process the surfaces of workpieces. This processing can involve macroscopic smoothing, where surfaces are ground flat and macroscopic irregularities are removed. Grinding can also be used to create a specific roughness, reducing microscopic surface roughness from previous processing steps and resulting in a higher-quality surface in terms of both surface finish and roughness.

[0003] Another objective of surface grinding can be to achieve a specific optical pattern. This involves creating a desired, predetermined grinding pattern on the surface through relative movement between the grinding tool and the workpiece surface. This movement is often generated by rotation of the grinding tool, superimposed with a translational movement of the workpiece and, if necessary, further superimposed pivoting or rotational movements around other axes between the grinding tool and the workpiece.

[0004] Various types of grinding tools can be used for such grinding processes. One versatile type is the disc brush, which employs a disc-shaped abrasive carrier. This carrier has numerous abrasive elements on an axial end face that points towards the workpiece. These elements can be, for example, abrasive bristles or sections of sandpaper. The disc-shaped abrasive carrier is then rotated around a central axis that is perpendicular or slightly inclined to the surface of the workpiece being processed. This rotation generates a component of the relative motion between the grinding tool or the abrasive elements and the surface.Another design of a grinding tool is the roller brush, in which a cylindrical circumferential surface faces the workpiece and the grinding tool rotates around a central axis that corresponds to the cylinder's central axis.

[0005] The abrasive elements are often formed by an abrasive carrier coated with abrasive grains such as corundum or other sharp-edged grains made of suitable hard materials. The abrasive elements are bonded to or embedded within the surface of the abrasive carrier. Because these abrasive elements have a certain length, wear caused by abrasion or grain break-off can be compensated for over a longer machining period. This is achieved by the abrasive elements shortening accordingly, thus continuously bringing new, sharp-edged grains into contact with the workpiece surface.

[0006] Due to their design, the abrasive elements are somewhat flexible and are moved across the workpiece surface during machining using a rotating, dragging motion. Consequently, they do not protrude from the abrasive carrier in a perfectly axial alignment, but are bent backwards against the direction of movement by a circumferential force caused by the rotational motion, so that an end section of the forward-facing surface of the abrasive elements rests on the workpiece surface.

[0007] Such an abrasive element can be formed by a section of sandpaper. For the purposes of the invention, a section of sandpaper is understood to be a flexible, sandpaper-like element that, on the one hand, has a flexible carrier material, which can be, for example, paper- or textile-like, to which the abrasive grains can be attached by means of a suitable bonding material. The end section, which rests on the surface to be sanded, can form at least a linear, preferably planar, contact between a portion of the total surface area of ​​the sandpaper section and the surface of the workpiece.

[0008] Despite the relatively long service life of such disc brushes, a problem arises in grinding processes: wear of the brush affects the grinding result, altering either the optical properties of the surface or its qualitative characteristics, such as flatness and roughness, and in particular, causing it to fall outside the desired tolerance range. This can result in insufficient grinding action, leading to inadequate material removal and potentially an undesirable polishing effect instead of effective grinding. Consequently, the grinding process can result in insufficient smoothing while simultaneously producing a surface roughness that does not meet the desired target value.

[0009] It is known to optically detect the surface of the workpiece in order to incorporate such changes into the control of grinding parameters or to infer from such changes the need to replace the disc brush and initiate a corresponding replacement. For example, grinding machines with such detection systems are known from DE 102018105133A1 and DE102018105134A1. While such technology allows for a significantly better adjustment of the desired surface quality, even with wear of the disc brush occurring during machining.However, on the one hand, there are certain limits to compensating for the wear of the disc brush by adjusting grinding parameters, and on the other hand, adjusting grinding parameters depending on the measurement of surface properties often only extends the service life of the disc brush insignificantly, so that even with these known solutions, the disc brush or the several disc brushes used in the grinding machine must be replaced at regular intervals, resulting in downtime and investment that reduces the efficiency of the grinding machine.

[0010] The invention is based on the objective of providing a grinding machine and a grinding process with which more economical surface processing is achieved.

[0011] This problem is solved according to the invention in that the majority of the abrasive elements have a majority of first surfaces provided with first abrasive bodies for contact with the surface of the object during a first direction of movement of the abrasive carrier and a majority of second surfaces provided with second abrasive bodies for contact with the surface of the object during a second direction of movement of the abrasive carrier opposite to the first, and in that the abrasive drive device is designed to drive the grinding tool in the first direction of movement, in which the first surfaces of the abrasive elements are in grinding engagement with the surface of the object and in the second direction of movement, in which the second surfaces of the abrasive elements are in grinding engagement with the surface of the object, and furthermore in that a control device is provided.which is coupled to the abrasive drive unit via signal technology and designed to switch the abrasive drive unit back and forth between the first and second directions of movement.

[0012] According to the invention, the abrasive carrier is provided with first and second surfaces by the majority of abrasive elements, each surface being equipped with abrasive elements. The first surfaces are oriented such that they point in a first direction of movement of the grinding tool and thus come into contact with the surface of the object during this first direction of movement of the abrasive carrier. This can be achieved, for example, by abrasive elements designed in the manner of sandpaper sections, which have a surface equipped with abrasive elements that are bent by the grinding force in the opposite direction of movement and thus come into contact with the surface of the object to be ground.In the case of disc brushes, this can be achieved, for example, by designing the abrasive elements as sections of sandpaper that extend axially from the disc and have the first surfaces pointing in a first circumferential direction.

[0013] According to the invention, a plurality of second surfaces, which are also provided with corresponding abrasive elements, are further provided by the plurality of abrasive elements on the abrasive carrier. These second surfaces point in a second direction of movement, which is opposite to the first direction of movement, and in this direction of movement lie against the surface of the object, which, as explained above, can be achieved by appropriately bending and conforming sections of abrasive paper that form these second surfaces.

[0014] The second surfaces preferably do not contact the object's surface during the first direction of movement, and conversely, the first surfaces do not contact the object's surface during the second direction of movement. In disc brushes, this can be achieved, for example, by designing the abrasive elements as sections of sandpaper that extend axially from the disc, with the second surfaces oriented in a second circumferential direction opposite to the first.

[0015] According to the invention, the abrasive drive device is further designed to selectively move the abrasive elements in both the first and second directions of movement relative to the surface of the object, i.e., to reverse the direction of movement accordingly, for which purpose, according to the invention, a corresponding control device for the abrasive drive device is further provided, which controls a corresponding reversal between the first and second directions of movement, i.e., switches the movement from the movement along the first direction of movement to a movement along the second direction of movement and vice versa.

[0016] The invention thus enables the grinding tool to achieve a grinding effect in two different directions of movement of the abrasive carrier, thereby bringing different surfaces of the grinding tool into grinding contact. This extends the service life of the grinding tool compared to previously known grinding tools; furthermore, it allows the grinding effect to be changed by reversing the direction of movement, thereby enabling desired optical grinding results to be achieved over a longer period or achieving previously unattainable optical results caused by reversing the direction of movement.

[0017] According to a first preferred embodiment, the abrasive drive device is designed to drive the grinding tool into a rotational movement as the first relative movement, and the control device is designed to switch the rotational movement between clockwise and counterclockwise rotation. This type of further development of the abrasive drive device allows, on the one hand, an efficient relative movement between the grinding tool and the surface to be achieved for surface processing and is well suited for many desired surface structuring applications, and, on the other hand, the use of grinding tools designed for such a rotational movement, such as disc brushes.

[0018] It is even more preferred if the abrasive drive device is designed to rotate the grinding tool around a grinding rotation axis, and the grinding rotation axis is formed on a grinding tool guide element that is pivotably or rotatably mounted about a guide axis that is not coaxial with the grinding rotation axis and is preferably arranged parallel to and spaced apart from the grinding rotation axis. According to this embodiment, in addition to the rotation of the grinding tool around the grinding rotation axis itself, a superimposed movement of the grinding rotation axis about a spaced-away guide axis is performed, which offers several advantages. Firstly, this allows several grinding tools to be used simultaneously and side-by-side, like satellites, for grinding operations and to be pivoted or rotated about a common guide axis.This increases the working area covered by the grinding tools and also makes it possible to further enlarge this area by pivoting or rotating it around the guide axis. In conjunction with the conveying device that transports the object through the grinding machine, this allows for movement in three axes, enabling both a variably configurable grinding motion and the coverage of a large surface area by the grinding tools. In this application, the extended service life provided by the invention is particularly advantageous, and the additional possibility of reversing the rotation of the grinding tools around the axis of rotation allows for particularly economical machining.

[0019] It is preferred that the control device is designed to control at least two independent relative movements between the grinding tool and the surface of the workpiece in such a way that, by superimposing these relative movements, the first surfaces in one area swept by the grinding tool and the second surfaces in another area swept by the grinding tool are in contact with the surface of the workpiece, thereby enabling the creation of special grinding patterns that were not achievable with previous grinding machines.

[0020] It is further preferred that the conveying device is designed to transport the object through the grinding machine in a translational, and in particular linear, motion. The conveying device can, in particular, be designed as an endless conveyor belt on which the objects can be placed, wherein the contact surface of the conveying device is preferably designed for high static friction with respect to the objects or has fastening means such as vacuum suction cups for holding the objects. A relative movement with respect to the surface of the workpiece essentially corresponds to a relative movement with respect to the contact surface of the conveying device, i.e., in this case, the endless conveyor belt.

[0021] According to a further preferred embodiment, some or each of the abrasive elements has a planar abrasive carrier element, which is coated on a front surface with the first abrasive elements and on a back surface with the second abrasive elements. In this embodiment, some or each of the abrasive elements are designed such that they are coated on both sides with abrasive elements such as corundum grains or the like, thereby forming a front surface and a back surface effective for the grinding action, which accordingly constitute the first surfaces and the second surfaces.The grinding tool can then be designed in such a way that a plurality of such abrasive elements coated on both sides with abrasive bodies are provided on it, in particular in such a way that all abrasive elements are coated on both sides or that some of the abrasive elements are coated on both sides and other abrasive elements are coated on one side only.The single-sided coated abrasive elements can be arranged on the abrasive carrier in such a way that they all point to the same side with the surface coated with abrasive bodies and consequently only engage with the surface in one direction of movement, or they can be arranged in such a way that some of the single-sided coated abrasive elements point with the grinding surface in one direction and some in the other direction, so that the single-sided coated abrasive elements exert a grinding effect in both directions of movement of the grinding tool.

[0022] According to a further preferred embodiment, the plurality of abrasive elements comprises a plurality of first planar abrasive carrier elements, each of which is coated with the first abrasive bodies on a front surface forming the first surface and is not coated with abrasive bodies on a back surface, and a plurality of second planar abrasive carrier elements, each of which is not coated with abrasive bodies on a front surface and is coated with the second abrasive bodies on a back surface forming the second surface, and the first and second abrasive carrier elements are arranged on the abrasive carrier in such a way thatthat in the first direction of movement, the front surfaces of the first and second abrasive carrier elements bear against the surface of the object, and in the second direction of movement, the rear surfaces of the first and second abrasive carrier elements bear against the surface of the object. According to this embodiment, the grinding tool comprises a plurality of abrasive elements coated with abrasive media on only one side. These are divided into first and second abrasive carrier elements, which are oriented differently. The first abrasive carrier elements are arranged on the abrasive carrier such that their surface coated with abrasive media engages with the surface of the object in the first direction of movement and grinds this surface. The second abrasive carrier elements are attached to the abrasive carrier in such a way that...that their abrasive-coated surface engages with the object's surface during the second direction of movement and grinds it. The grinding tool can thus be constructed from conventional, single-sided coated sandpaper sections by attaching them to the abrasive backing in two different orientations, thereby generating a grinding effect in both directions of movement.

[0023] It is particularly preferred if the first and second grinding body carrier elements are alternately attached to the grinding body adjacent to each other, such that the front surface of a first grinding body carrier element faces the rear surface of a second grinding body carrier element adjacent on a first side and the rear surface of the first grinding body carrier element faces a front surface of a second grinding body carrier element adjacent on a second side.In such an alternating arrangement of the two differently oriented abrasive carrier elements, one abrasive element is attached to the carrier in such a way that its surface coated with abrasive particles is oriented to grind the surface in the first direction of movement. Adjacent to this, an abrasive element is positioned whose surface coated with abrasive particles is oriented to grind the surface in the second direction of movement. Consequently, on the grinding tool, two surfaces of the abrasive elements coated with abrasive particles and two surfaces of the abrasive elements not coated with abrasive particles are alternately facing each other.This arrangement ensures a uniform grinding effect of the abrasive elements over the entire working length of the grinding tool, i.e., over the entire circumference of the grinding tool in the case of disc brushes, in both directions of movement, and achieves favorable absorption of detached abrasive grains within the grinding tool.

[0024] This form of further development can be enhanced by connecting the first and second abrasive carrier elements, specifically by partially or fully bonding the back surface of the first abrasive carrier element to the front surface of the second abrasive carrier element. According to this embodiment, the mutually facing, uncoated surfaces of the abrasive elements are connected, in particular by bonding them together over their entire surface.This combination achieves, on the one hand, an efficient manufacturing method for the grinding tool, and on the other hand, a reduction in the flexural rigidity of the abrasive elements, which is advantageous for grinding operations. This is accomplished by creating a sandwich element consisting of two abrasive elements, coated on both sides with abrasive media. This element exhibits well-designed stiffness against bending and thus avoids unfavorable large-area contact of the abrasive media-coated surface with the surface of the object, even under higher contact pressures of the grinding tool against the surface. This results in more economically efficient grinding operations.

[0025] As an alternative to the previously described alternating adjacent arrangement of the abrasive elements, another embodiment preferably provides that a first group of several first abrasive carrier elements are arranged side by side on the abrasive carrier and a second group of several second abrasive carrier elements are arranged side by side on the abrasive carrier and at least a first group and a second group are attached to the abrasive carrier, preferably several first and second groups are attached to the abrasive carrier alternately adjacent to each other.According to this embodiment, the abrasive elements are not alternately attached to the abrasive carrier in different orientations, but rather several abrasive elements forming a group, whose surface provided with abrasive bodies faces the same side and consequently causes an abrasive effect on the surface of the object in the same direction of movement, are grouped together and arranged, whereas several abrasive elements grouped together to form a second group are attached to the abrasive carrier in such a way that their surface provided with abrasive bodies faces in the opposite direction and consequently engages with the surface of the object in the second direction of movement.This can be implemented, for example, such that only the first and second groups of abrasive carrier elements are present on the grinding tool; for instance, in the case of a disc brush, the first and second groups each extend over 180° of the circumference. However, the embodiment can also be designed such that a plurality of first and second groups are present on the grinding tool; for example, each group may contain only two, three, four, or more abrasive elements attached to the abrasive carrier with the same orientation, and then a plurality of the first and second groups constitutes the majority of the abrasive elements.

[0026] Such a group arrangement achieves, on the one hand, an advantageous grinding effect through several successive surfaces of the abrasive elements covered with abrasive bodies in one section of the grinding tool, and on the other hand, an advantageous cleaning and wiping effect through several successive surfaces of the abrasive elements without abrasive bodies in another section of the grinding tool, thereby reducing the risk of broken-out abrasive bodies adversely affecting the grinding result.

[0027] In a further preferred embodiment, it is provided that the majority of the abrasive elements are designed as a plurality of flexible abrasive paper sections, and the abrasive carrier is designed as a plate- or ring-shaped support having an axial end face to which the majority of the sandpaper sections are attached, or as a cylindrical support having a circumferential surface to which the majority of the sandpaper sections are attached, wherein in both alternative embodiments of the carrier the first and second directions of movement are achieved by a rotation of the carrier clockwise and counterclockwise. The abrasive elements are formed in a clockwise direction and attached to the carrier such that, when the carrier rotates clockwise, their front side rests against a workpiece onto which the abrasive elements are pressed. When the direction of rotation is reversed, the abrasive elements flip over so that their back side rests against the workpiece. In this embodiment, the abrasive tool is designed as a disc brush or a roller brush, and the abrasive elements are arranged over a circumferential section on an axial end face of the disc-shaped abrasive carrier or on a circumferential surface of the cylindrical carrier. The abrasive elements are designed as abrasive paper sections and, according to the previously described preferred embodiments, can be coated on one or both sides with abrasive media.In this context, a section of sandpaper is generally understood to be a flat, flexible element that has an abrasive carrier element, which is designed as paper of a certain thickness, as a plastic film, as a textile carrier, as a textile fabric or the like, and which is accordingly coated on one or both sides with abrasive elements. Alternatively, abrasive elements can also be used as such a section of sandpaper, which have abrasive elements embedded in a bonding material designed as an abrasive carrier element, wherein the abrasive elements are arranged in the bonding material in such a way that they exert an abrasive effect on one or both sides.

[0028] Finally, according to a further preferred embodiment of the grinding machine according to the invention, the first grinding media of the first surfaces have a first grain size, and the second grinding media of the second surfaces have a second grain size that differs from the first grain size. According to this embodiment, the first and second surfaces are provided with grinding media of different grain sizes, so that during the first direction of movement of the grinding tool, grinding media with a first grain size come into contact with the surface during the grinding process, and during the second direction of movement, grinding media with a different grain size come into contact with the surface during the grinding process. This embodiment can be implemented, in particular according to the preferred embodiments described above, with grinding media carrier elements coated on one or both sides.by coating an abrasive carrier element either on one side with a first grain size and on the other side with a second, different grain size, or by using abrasive elements that are coated on one side with abrasive media, wherein a first type of abrasive elements is formed by abrasive carrier elements that are coated on one side with abrasive media of a first grain size and that are oriented on the grinding tool in such a way that they come into grinding engagement with the surface in the first direction of movement, and a second type of abrasive elements is formed by abrasive carrier elements that are coated on one side with abrasive media of a second, different grain size and whose surface coated with abrasive media is oriented opposite to the abrasive elements of the first group.so that they come into grinding engagement with the surface when the grinding tool is moved in the second direction of movement relative to the surface.

[0029] In this preferred embodiment, it is therefore advantageously possible to perform a grinding operation with two different grain sizes and consequently, for example, to carry out a first grinding operation of the surface with a coarse grain to smooth out larger irregularities of the surface by moving the grinding tool in the first direction of movement relative to the surface, followed by a subsequent operation with the same grinding tool using a finer grain size to achieve a higher surface quality and lower roughness by moving the grinding tool in the second direction of movement relative to the surface of the object.This embodiment therefore avoids the need to change the grinding tool to achieve this grinding operation with coarse and fine grain, and the two-stage grinding operation can be carried out by a single grinding unit without changing the grinding tool in the grinding machine, so that the provision of another grinding unit in the grinding machine is also not necessary.

[0030] Another aspect of the invention is a grinding tool for grinding the surface of an object, comprising an abrasive carrier and a plurality of abrasive elements attached to the abrasive carrier, wherein the plurality of abrasive elements have a first surface provided with first abrasive elements for contact with the surface of the object during a first direction of movement of the abrasive carrier and a second surface provided with second abrasive elements for contact with the surface of the object during a second direction of movement of the abrasive carrier opposite to the first. The grinding tool according to this aspect of the invention is particularly suitable for use in a grinding machine of the previously described design according to the invention.The grinding tool has a plurality of abrasive elements that form first surfaces for contact with a surface being machined by the grinding tool when the grinding tool is moved across this surface in a first direction of movement, and second surfaces equipped with second abrasive elements that bear against a surface of a workpiece when the grinding tool is moved across this surface in a second direction of movement, different from the first. The first surfaces therefore point in a different direction than the second surfaces, in particular in the opposite direction.

[0031] The grinding tool is therefore suitable for use as explained above, i.e., to exert a grinding effect on the surface when the grinding tool is guided over the surface in a first direction of movement and subsequently in a second direction of movement, and as a result, the grinding tool according to the invention has a longer service life.

[0032] The grinding tool according to the invention can be further developed by having some or each of the grinding element have a planar grinding body carrier element which is coated on a front surface with the first grinding bodies and on a back surface with the second grinding bodies.

[0033] Furthermore, the grinding tool according to the invention can be further developed by having the majority of the abrasive elements comprise a majority of first planar abrasive carrier elements, each of which is coated with the first abrasive bodies on a front surface forming the first surface and is not coated with abrasive bodies on a back surface, and a majority of second planar abrasive carrier elements, each of which is not coated with abrasive bodies on a front surface and is coated with the second abrasive bodies on a back surface forming the second surface, and the first and second abrasive carrier elements are arranged on the abrasive carrier in such a way thatthat in the first direction of movement the front surfaces of the first and second grinding body carrier elements are in contact with the surface of the object, and in the second direction of movement the rear surfaces of the first and second grinding body carrier elements are in contact with the surface of the object.

[0034] Furthermore, the grinding tool according to the invention can be further developed by attaching the first and second grinding body carrier elements alternately adjacent to each other to the grinding body carrier, such that the front surface of a first grinding body carrier element faces the rear surface of a second grinding body carrier element adjacent on a first side and the rear surface of the first grinding body carrier element faces a front surface of a second grinding body carrier element adjacent on a second side.

[0035] Furthermore, the grinding tool according to the invention can be further developed by connecting the first and second grinding body carrier elements to each other, by partially or fully connecting the back surface of the first grinding body carrier element with the front surface of the second grinding body carrier element.

[0036] Furthermore, the grinding tool according to the invention can be further developed by arranging a first group of several first grinding body carrier elements side by side on the grinding body carrier and a second group of several second grinding body carrier elements side by side on the grinding body carrier, and by attaching at least a first group and a second group to the grinding body carrier, preferably several first and second groups alternately adjacent to each other on the grinding body carrier.

[0037] Furthermore, the grinding tool according to the invention can be further developed by designing the majority of the abrasive elements as a plurality of sandpaper sections, is designed as a plate- or ring-shaped support having an axial end face to which the majority of the sandpaper sections are attached, or as a cylindrical support having a circumferential surface to which the majority of the sandpaper sections are attached, wherein the first and second directions of movement are formed by a rotation of the carrier clockwise and counterclockwise, and the sandpaper sections are attached to the carrier in such a way that, when the carrier is rotated clockwise, their front side rests against a workpiece onto which the abrasive elements are pressed, and when the direction of rotation is reversed, they fold over so that instead of the front side, a back side of the sandpaper sections rests against the workpiece.

[0038] Furthermore, the grinding tool according to the invention can be further developed by having the first grinding bodies of the first surfaces have a first grain size and the second grinding bodies of the second surfaces have a second grain size that differs from the first grain size.

[0039] These further developments of the grinding tool according to the invention correspond to those further developments of the grinding tool used in the grinding machine according to the invention described above, and with regard to the variants and advantages of these further developments for the grinding tool according to the invention, reference is made to the variants and advantages of the grinding machine according to the invention with the correspondingly further developed grinding tool described above.

[0040] Finally, another aspect of the invention is a method for grinding a surface of an object, comprising the steps of: grinding the surface of the object by means of one or more grinding tools, each of which has a plurality of abrasive elements attached to at least one movably mounted abrasive carrier, wherein the plurality of abrasive elements of a grinding tool has a first surface provided with first abrasive bodies for contact with the surface of the object during a first direction of movement of the abrasive carrier and a second surface provided with second abrasive bodies for contact with the surface of the object during a second direction of movement of the abrasive carrier opposite to the first.and that in a first processing step the grinding tool is moved in the first direction of movement over the surface of the object in grinding engagement, and in a subsequent second processing step it is moved in the second direction of movement over the surface of the object in grinding engagement.

[0041] The inventive method can be carried out, in particular, with a grinding machine or a grinding tool of the previously described design. The grinding method according to the invention is characterized by a long service life of the grinding tool and the resulting economical grinding process. It also has the further advantage that, by allowing the direction of movement of the grinding tool to be reversed and grinding to be performed in both directions, it can generate a greater variety of surface structures and patterns.

[0042] The grinding method according to the invention can be further developed in particular by having the first grinding bodies of the first surfaces have a first grain size and by having the second grinding bodies of the second surfaces have a second grain size that differs from the first grain size, by the steps: Coarse grinding of the surface in the first processing step and fine grinding of the surface in the second processing step.

[0043] This type of grinding process involves a two-stage machining operation. In the first stage, a grinding tool efficiently smooths larger surface irregularities on the workpiece, followed by a second stage of fine-tuning the surface to achieve a low roughness. This is accomplished without requiring the use of two different grinding tools or two different grinding units with correspondingly different grinding tools within a single grinding machine. As a result, machining speed and versatility are significantly increased.

[0044] In addition to this two-stage processing, a further preferred embodiment of the grinding method according to the invention involves machining a first workpiece with the grinding tool through the first surface in a first direction of movement, and then machining a second workpiece in a subsequent machining operation with the second direction of movement through the second surface of the grinding tool. This ensures that any contamination of the grinding tool on the first surface resulting from the machining of the first workpiece, such as from a layer of paint removed during the grinding process, has no effect on the subsequent second machining operation of the second workpiece, because different surfaces of the grinding tool are used.Furthermore, this processing method makes it possible to machine workpieces of different hardness by fitting the first and second surfaces of the grinding tool with grinding media of different grain sizes, as explained above, and thereby enabling the grinding effect to be adapted to workpieces with different properties by appropriately selecting the direction of movement of the grinding tool.

[0045] A preferred embodiment of a grinding tool and a grinding machine according to the invention is explained with reference to the following figures. These show: Fig. 1 : a schematic representation of a preferred embodiment of a grinding tool according to the invention in a first direction of movement, and Fig. 2 : a schematic representation of the preferred embodiment according to Figur 1 in a second direction of movement Fig. 3a-d : schematic representations of the lower end face of four different grinding tools according to the invention, Fig. 4 : a schematic representation of a preferred embodiment of a grinding machine according to the invention. Fig. 5A , B: a first and a second advantageous procedure of a grinding process according to the invention are illustrated.

[0046] Referring first to Fig. 1 In the preferred embodiment, a grinding tool according to the invention is designed as a disc brush and comprises an abrasive carrier 10, which is disc-shaped and has a central opening 11 for receiving a drive shaft, which defines the axis of rotation 12 of the grinding tool. A plurality of abrasive elements 20a, b, c, d, e, ... are attached to an end face 10a of the abrasive carrier 10 around its entire circumference, of which only some are shown. Each abrasive element is formed by a rectangular textile carrier section covered on both sides with abrasive grains.These abrasive elements are flexible and, depending on the direction of rotation of the grinding tool, can bend around the axis of rotation 12 due to the frictional action acting on these abrasive elements at their outer end when they are pressed against a workpiece surface to be machined. This causes either a first surface 21a-e or a second surface 22a-e, depending on the direction of rotation A or B, to come into grinding engagement with this surface. Fig. 1 The grinding tool is driven in direction A (clockwise when viewed from above on end face 10a) and the abrasive elements are bent backwards in the opposite direction of rotation and their first surfaces rest against a workpiece (not shown). Fig. 2 The grinding tool is driven in the direction of rotation b (counterclockwise when viewed from above on the end face 10a) and the abrasive elements 21a-e are bent backwards against this direction of rotation and lie with the second surfaces 22a-e against the workpiece (not shown).

[0047] Fig. 3a shows an abrasive carrier 110, on the end face of which a plurality of sandpaper sections 120a, b, c,... coated on both sides 121a,b,c, 122a,b,c with abrasive bodies such as corundum grains are attached over a ring-shaped circumferential area.

[0048] In a Fig. 3b In the variant shown, the abrasive carrier 210 also has a plurality of abrasive elements 220a,b,c,d,... which, however, in this embodiment are coated with abrasive media only on one side 221a,c, 222b,d. The abrasive elements are arranged such that abrasive elements with different orientations are alternately distributed around the circumference of the abrasive carrier, so that the grinding surfaces 221a,c point clockwise and the grinding surfaces 222b,d point counterclockwise.

[0049] In a Fig. 3c In the illustrated variant, the abrasive carrier 310 also has a plurality of abrasive elements 320a,b,c, 320a`,b`,c`, which, however, in this embodiment are coated with abrasive media only on one side. The abrasive elements are arranged such that groups 323a,b,c of five abrasive elements oriented in the same direction are combined, and these groups are alternately distributed with different orientations around the circumference of the abrasive carrier. Thus, this plurality of abrasive elements also has first surfaces 321a-c, which, in a first direction of rotation, come into grinding engagement with the surface of a workpiece against which the grinding tool is pressed, and second surfaces 322a-c, which come into grinding engagement with the surface when the grinding tool is moved in a second, opposite direction of rotation.

[0050] Fig. 3d shows a fourth variant, which is just like Fig. 3b is equipped with single-sided coated abrasive elements 420a,b,c,d,... In this embodiment, the abrasive elements are also, as in Fig. 3b , arranged alternately around the circumference in the first and second orientations. The sides 424b,d, 425a,c of the abrasive elements that are not coated with abrasive media lie directly against each other and may be bonded together.

[0051] Fig. 4 Figure 1 shows a section of a grinding machine featuring a disc brush grinding module 500. Several satellite-like grinding tools 530a,b,c,... are arranged on this disc brush grinding module, their design being similar to that of the Fig. 1 und 2 and the Figuren 3a, 3b or 3c can correspond.

[0052] These grinding tools 530 are rotated within the disc brush grinding module on the one hand around their respective disc brush rotation axis 530'a,b,c,..., whereby this rotational movement can be carried out by the grinding machine in a clockwise and counterclockwise direction in order to bring the first and second surfaces of the grinding elements into engagement with a surface to be machined accordingly.

[0053] The workpieces to be processed are conveyed by the grinding machine on an endless conveyor belt 550 under the disc brushes. The disc brushes of the disc brush grinding module are attached as a triple satellite arrangement to a disc brush carrier 540 a, b, c,... which in turn is rotatably mounted about a satellite carrier axis 540'a,b,c,... and thereby causes a superimposed rotation about the disc brush rotation axes 530'a,b,c,... around a satellite carrier axis 540'a. This allows even a large workpiece, which has a width corresponding to the width of the endless conveyor belt, to be ground uniformly by the disc brush grinding module.

[0054] In principle, the grinding machine according to the invention can be operated such that the rotational speed of the disc brushes about the disc brush rotation axes is many times greater than the rotational speed at which the disc brush rotation axes are rotated about the satellite carrier axis. In this case, the rotational speed of the disc brushes about the disc brush rotation axis determines the bending direction of the flexible abrasive elements, and this bending occurs uniformly.However, if the ratio of the rotational speed around the disc brush axes to the rotational speed around the satellite carrier axis is reduced to a certain level, or even if the rotational speed around the satellite carrier axis is increased to a multiple of the rotational speed around the axis of rotation, the relative speed of the abrasive elements to the workpiece surface is reversed during one full revolution of the grinding tool around the disc brush rotation axis. This causes the abrasive elements to flip from grinding with the first surface to grinding with the second surface. In this case, the flexible contact direction of the abrasive elements is changed twice during one revolution of the grinding tool around the axis of rotation, and the abrasive elements grind with the first surface in a first section and with the second surface in a second section during this revolution.This can be advantageous in certain applications to achieve specific grinding patterns on the surface of the workpiece.

[0055] Fig. 5A Figure 1 shows a first step of the grinding process according to the invention. In a first machining step 1000, the workpiece is ground by the first surfaces of the grinding tools by moving the grinding tools in a first direction of movement relative to the surface. In this first machining step, the workpiece is moved through the grinding machine by means of the endless conveyor belt in a first conveying direction and is thereby guided under the grinding tools while the grinding operation takes place.

[0056] In a subsequent second machining operation (1100) of a second workpiece, this second workpiece is moved under the grinding tool in the same direction of movement of the conveyor. However, the direction of movement of the grinding tools is reversed, and the grinding tools therefore machine the second workpiece with the second surface. Any contamination or wear of the first surfaces of the abrasive elements caused by the first workpiece thus does not affect the machining quality of the second workpiece.

[0057] In Fig. 5BA second, alternative sequence of the grinding process according to the invention is shown. Again, as in the first process sequence, a workpiece is first machined in a first machining step 2000 by the grinding tools with the first surfaces of the abrasive elements, by guiding the workpiece through the conveying device under the disc brushes and the disc brushes rotating in a first direction of rotation and consequently bringing the first surfaces of the abrasive elements into grinding engagement.

[0058] After the workpiece has completely passed under the disc brushes, in this process sequence, a second processing step (2100) involves either reversing the direction of movement of the conveyor device and guiding the workpiece under the disc brushes in the opposite direction. In this step, the direction of rotation of the disc brushes is reversed, and the disc brushes are consequently guided over the surface in the second direction of movement, bringing the second surfaces of the abrasive elements into contact with the surface. These second surfaces preferably have a finer grit than the first surfaces, so that in this second processing step, a finer finish is achieved, resulting in the production of a high-quality surface with low roughness.

[0059] Alternatively, instead of reversing the direction of movement of the conveyor device, the workpiece can also be removed from the grinding machine in an intermediate step 2200, fed back into the grinding machine at the front end, and in the second processing step 2100 fed back to the disc brush grinding unit with the conveyor device in the same direction of movement. As before, the disc brushes are then driven in the second direction of movement during this second processing step, so that the second processing takes place with the second surfaces of the abrasive elements.

Claims

1. A grinding machine for grinding a surface of an object, comprising a. at least one grinding tool with a movably mounted abrasive carrier and a plurality of abrasive elements fastened to the abrasive carrier, and c. an abrasive drive device for driving the grinding tool in a first relative movement to the object, d. a conveyor device for conveying the object with a second relative movement to the grinding tool through the grinding machine, characterized in thatthe plurality of abrasive elements comprises a plurality of first surfaces provided with first abrasive bodies for engaging the surface of the object in a first direction of movement of the abrasive carrier and a plurality of second surfaces provided with second abrasive bodies for engaging the surface of the object in a second direction of movement of the abrasive carrier opposite to the first direction of movement, and in that the abrasive drive device is designed to be operated in the first direction of movement in which the first surfaces of the abrasive elements are in grinding engagement with the surface of the object and in the second direction of movement in which the second surfaces of the abrasive elements are in grinding engagement with the surface of the object, and further characterized bya control device which is signal-coupled to the abrasive drive device and is designed to switch the abrasive drive device back and forth between the first and the second direction of movement.

2. Grinding machine according to claim 1, characterized in that the grinding means drive device is designed to drive the grinding tool into a rotational movement as a first relative movement and the control device is designed to switch the rotational movement back and forth between a clockwise rotation and a counterclockwise rotation, and / or characterized in thatthe abrasive means drive device is designed to set the grinding tool in rotation about a grinding rotation axis and the grinding rotation axis is formed on a grinding tool guide element which is pivotally or rotatably mounted about a guide axis which is not aligned coaxially with the grinding rotation axis, in particular is arranged parallel to and at a distance from the grinding rotation axis.

3. Grinding machine according to one of the preceding claims, characterized in that the conveying device is designed to convey the object in a translational, in particular linear, movement through the grinding machine, and / or characterized in that some or each of the abrasive elements comprises a planar abrasive body carrier element which is coated on a front surface with the first abrasive bodies and coated on a rear surface with the second abrasive bodies.

4. Grinding machine according to one of claims 1-3, characterized in thatwhich has the plurality of abrasive elements - a plurality of first flat abrasive body carrier elements, each of which is coated with the first abrasive bodies on a front surface forming the first surface and is not coated with abrasive bodies on a back surface, - a plurality of second flat abrasive body carrier elements, each of which is not coated with abrasive bodies on a front surface and is coated with the second abrasive bodies on a back surface forming the second surface, and - the first and second abrasive body carrier elements are arranged on the abrasive carrier such that in the first direction of movement the front surfaces of the first and second abrasive body carrier elements rest against the surface of the object and in the second direction of movement the back surfaces of the first and second abrasive body carrier elements rest against the surface of the object.

5. Grinding machine according to claim 4, characterized in that the first and second abrasive body carrier elements are each fastened alternately adjacent to one another on the abrasive carrier, so that the front surface of a first abrasive body carrier element faces the rear surface of a second abrasive body carrier element adjacent on a first side and the rear surface of the first abrasive body carrier element faces a front surface of a second abrasive body carrier element adjacent on a second side, wherein preferably the first and second abrasive body carrier elements are connected to one another in that the rear surface of the first abrasive body carrier element is partially or fully connected to the front surface of the second abrasive body carrier element.

6. Grinding machine according to claim 4, characterized in thata first group of a plurality of first abrasive body carrier elements are arranged next to one another on the abrasive carrier and a second group of a plurality of second abrasive body carrier elements are arranged next to one another on the abrasive carrier and at least one first group and one second group are fastened to the abrasive carrier, preferably a plurality of first and second groups are fastened alternately adjacent to one another on the abrasive carrier.

7. Grinding machine according to one of the preceding claims, characterized in thatthe majority of the abrasive elements are designed as a plurality of flexible sandpaper sections, and the abrasive carrier - is designed as a plate-shaped or ring-shaped carrier which has an axial end face to which the majority of the sandpaper sections are fastened, or - is designed as a cylindrical carrier which has a circumferential surface to which the majority of the sandpaper sections are fastened, wherein the first and second directions of movement are formed by a clockwise and counterclockwise rotation of the carrier, and the sandpaper sections are fastened to the carrier in such a way that, when the carrier rotates clockwise, they rest with a front side on a workpiece onto which the abrasive elements are pressed, and when the direction of rotation is reversed, they fold over so that, instead of the front side, a back side of the sandpaper sections rests on the workpiece.

8. Grinding machine according to one of the preceding claims, characterized in that the first abrasive bodies of the first surfaces have a first grain size and the second abrasive bodies of the second surfaces have a second grain size which is different from the first grain size.

9. A grinding tool for grinding a surface of an object, comprising an abrasive carrier and a plurality of abrasive elements attached to the abrasive carrier, characterized in that the plurality of abrasive elements has a first surface provided with first abrasive bodies for contact with the surface of the object in a first direction of movement of the abrasive carrier and a second surface provided with second abrasive bodies for contact with the surface of the object in a second direction of movement of the abrasive carrier opposite to the first.

10. Grinding tool according to claim 9, characterized in thatsome or each of the abrasive elements has a flat abrasive body carrier element which is coated on a front surface with the first abrasive bodies and coated on a rear surface with the second abrasive bodies.

11. Grinding tool according to one of claims 9-10, characterized in thatthe plurality of abrasive elements - comprises a plurality of first flat abrasive body carrier elements, each of which is coated with the first abrasive bodies on a front surface forming the first surface and is not coated with abrasive bodies on a rear surface, - comprises a plurality of second flat abrasive body carrier elements, each of which is not coated with abrasive bodies on a front surface and is coated with the second abrasive bodies on a rear surface forming the second surface, and - the first and second abrasive body carrier elements are arranged on the abrasive carrier such that, in the first direction of movement, the front surfaces of the first and second abrasive body carrier elements rest against the surface of the object, and, in the second direction of movement, the rear surfaces of the first and second abrasive body carrier elements rest against the surface of the object,wherein preferably the first and second abrasive body carrier elements are each alternately attached to the abrasive carrier adjacent to one another, so that the front surface of a first abrasive body carrier element faces the rear surface of a second abrasive body carrier element adjacent on a first side and the rear surface of the first abrasive body carrier element faces a front surface of a second abrasive body carrier element adjacent on a second side.

12. Grinding tool according to claim 11, characterized in thatthe first and second abrasive body carrier elements are connected to one another in that the rear surface of the first abrasive body carrier element is partially or fully connected to the front surface of the second abrasive body carrier element, wherein preferably a first group of several first abrasive body carrier elements are arranged next to one another on the abrasive carrier and a second group of several second abrasive body carrier elements are arranged next to one another on the abrasive carrier and at least a first group and a second group are fastened to the abrasive carrier, preferably several first and second groups are fastened alternately adjacent to one another on the abrasive carrier.

13. Grinding tool according to one of the preceding claims 9-12, characterized in thatthe majority of the abrasive elements are designed as a plurality of sandpaper sections, and the abrasive carrier - is designed as a plate-shaped or ring-shaped carrier which has an axial end face to which the majority of the sandpaper sections are fastened, or - is designed as a cylindrical carrier which has a circumferential surface to which the majority of the sandpaper sections are fastened, wherein the first and second directions of movement are formed by a clockwise and counterclockwise rotation of the carrier, and the sandpaper sections are fastened to the carrier in such a way that, when the carrier rotates clockwise, they rest with a front side on a workpiece onto which the abrasive elements are pressed, and when the direction of rotation is reversed, they fold over so that, instead of the front side, a back side of the sandpaper sections rests on the workpiece.

14. Grinding tool according to one of the preceding claims 9-13, characterized in that the first abrasive bodies of the first surfaces have a first grain size and the second abrasive bodies of the second surfaces have a second grain size which is different from the first grain size.

15. A method for grinding a surface of an object, comprising the steps of: grinding the surface of the object by means of one or more grinding tools, each of which has a plurality of abrasive elements attached to at least one movably mounted abrasive carrier, characterized in thatthe majority of the abrasive elements of a grinding tool have a first surface provided with first abrasive bodies for contact with the surface of the object in a first direction of movement of the abrasive carrier and a second surface provided with second abrasive bodies for contact with the surface of the object in a second direction of movement of the abrasive carrier opposite to the first, and that the grinding tool is moved in a first processing step in the first direction of movement in grinding engagement over the surface of the object and in a subsequent second processing step is moved in the second direction of movement in grinding engagement over the surface of the object, wherein preferably the first abrasive bodies of the first surfaces have a first grain size and the second abrasive bodies of the second surfaces have a second grain size that is different from the first grain size,with the steps: - rough grinding of the surface in the first processing step and - fine grinding of the surface in the second processing step.,

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