Patent Description:
The invention especially finds advantageous application in the sanding/finishing of bevelled edges of bars with an elongated shape used as beams or columns in the building industry, to which explicit reference will be made in the description below without because of this loosing in generality.

When dealing with the sanding/finishing of bevelled edges for bars for the building industry, a sanding machine such as disclosed in <CIT> or <CIT> is known, which comprises at least one sanding unit to sand/finish the bars; and a feeding device, which defines a support surface for at least one bar and is designed to move the bar in a horizontal direction parallel to the support surface and along a path extending through the sanding unit.

Generally speaking, the sanding unit comprises a frame, at least two pulleys (normally, three pulleys) mounted so as to rotate around respective longitudinal axes and an abrasive belt wound in a ring shape around the pulleys.

The sanding unit further comprises at least one pushing element, which is arranged between the pulleys and is movable between an operating position, in which it pushes the abrasive belt against the bevelled edges of the bar, and a rest position, in which it disengages the abrasive belt from the bar.

Since the bevelled edges of the bar have a relatively small width, in order to ensure a relatively even and uniform wear of the abrasive belt, the sanding unit is further provided with an operating device to move one of the pulleys with an oscillatory reciprocating motion around a rotation axis, which is transverse to the relative longitudinal axis.

The oscillatory reciprocating motion of the pulley generates a straight reciprocating motion of the abrasive belt along the pulleys parallel to the relative longitudinal axes.

The operating device normally comprises an actuator cylinder, which is provided with an output rod connected to the pulley and alternatively movable between an extracted position and a retracted position, and a photodetector, which is designed to selectively control the operation of the actuator cylinder.

In use, the actuator cylinder is activated in order to move the output rod from the retracted position to the extracted position, when the photodetector detects the passage of the abrasive belt, and is activated in order to move the output rod again from the extracted position to the retracted position after a constant amount of time.

Since the movement of the abrasive belt along the pulleys depends on the speed of movement of the abrasive belt around the pulleys, known sanding machines of the type described above suffer from some drawbacks, which are mainly due to the fact that the straight reciprocating motion of the abrasive belt is reversed, in one case, when the photodetector detects the passage of the abrasive belt and, in the other case, after the constant amount of time mentioned above has elapsed.

The object of the invention is to provide a sanding machine for sanding/finishing/brushing components made of wood, metal or the like, which does not suffer from the drawbacks described above and is simple and economic to be manufactured.

According to the invention, there is provided a sanding machine for sanding/finishing/brushing components made of wood, metal or the like according to the appended claims.

With reference to <FIG>, <FIG>, <FIG>, <FIG> and <FIG>, number <NUM> indicates, as a whole, a sanding machine for sanding/finishing/brushing components <NUM> made of wood, metal or the like, especially beams or columns for the building industry.

Each component <NUM> has an elongated shape and is delimited by an upper face <NUM> and by a lower face <NUM>, which are substantially parallel to one another, by two end faces <NUM>, which are substantially parallel to one another and perpendicular to the faces <NUM>, and by two side faces <NUM>, which are parallel to one another and perpendicular to the faces <NUM>.

The sanding machine <NUM> comprises a roller conveyor device <NUM>, which extends in a horizontal direction <NUM> and comprises, in turn, a plurality of motor-driven transport rollers <NUM>, which define a support surface A for the components <NUM> and are mounted so as to rotate around respective rotates axes <NUM>, which are parallel to one another and to a horizontal direction <NUM>, which is transverse to the direction <NUM>.

The components <NUM> are moved by the device <NUM> along a path P extending through a plurality of operating units, especially two operating units <NUM>, <NUM>, which are mounted between the rollers <NUM> and are each designed to process a relative face <NUM>.

The sanding machine <NUM> is provided with a limit stop device <NUM>, which is arranged upstream of the unit <NUM>, extends in the direction <NUM> and allows the components <NUM> to be correctly positioned in the direction <NUM>.

The unit <NUM> comprises an elongated frame <NUM>, which extends in the direction <NUM> and supports an intermediate slide <NUM>, which extends in the direction <NUM> and is coupled to the frame <NUM> in a sliding manner through the interposition of a shock absorber device <NUM> (<FIG>) so as to make, relative to the frame <NUM>, straight movements in the direction <NUM>.

The device <NUM> comprises, in particular, a pneumatic cylinder <NUM>, which is fixed to the frame <NUM> parallel to the direction <NUM>, a pneumatic cylinder <NUM>, which is fixed to the slide <NUM> parallel to the direction <NUM> and faces the cylinder <NUM>, and an output rod <NUM>, which is coupled to the cylinders <NUM>, <NUM> in a sliding manner.

The slide <NUM> supports two conveyor assemblies <NUM>, <NUM>, which are arranged on opposite sides of the path P in the direction <NUM> and define a feeding channel <NUM> feeding the components <NUM> through the unit <NUM>.

The assembly <NUM> is arranged on the side of the path P opposite the one of the device <NUM> and comprises a horizontal slide <NUM> with a substantially rectangular shape, which is mounted on the slide <NUM> is coupled to the slide <NUM> in a sliding manner and is further coupled, by means of a screw-nut screw coupling, to a screw <NUM> of a relative operating device <NUM> (<FIG>), a motor <NUM> thereof causing the rotation of the screw <NUM> in order to cause the slide <NUM> to make straight movements along the slide <NUM> in the direction <NUM>.

The device <NUM> further comprises a nut screw <NUM>, which is coupled to the screw <NUM> and is engaged by the slide <NUM> in a sliding manner through the interposition of a shock absorber device <NUM> (<FIG>) comprising two pneumatic cylinders <NUM>, which are mounted between the slide <NUM> and the nut screw <NUM> parallel to the direction <NUM>.

The assembly <NUM> is further provided with a rotary platform <NUM>, which is coupled to the slide <NUM> in a rotary manner so as to rotate, relative to the slide <NUM>, around a fulcrum axis <NUM>, which is parallel to a vertical direction <NUM> orthogonal to the directions <NUM> and <NUM> and is obtained at the entrance of the components <NUM> into the unit <NUM> and into the channel <NUM>.

The platform <NUM> is connected to the slide <NUM> through the interposition, in particular, of a shock absorber device <NUM> and of three coupling devices <NUM>.

The device <NUM> comprises, in particular, a pneumatic cylinder <NUM>, which is connected to the slide <NUM>, a pneumatic cylinder <NUM>, which is connected to the platform <NUM> and faces the cylinder <NUM>, and an output rod <NUM>, which is coupled to the two cylinders <NUM>, <NUM> in a sliding manner.

Each device <NUM> comprises a guide <NUM>, which is fixed to the slide <NUM> parallel to the direction <NUM>, a recirculating ball slider <NUM>, which is coupled to the guide <NUM> in a sliding manner, a guide <NUM>, which is obtained on the slider <NUM> parallel to the direction <NUM>, a recirculating ball slider <NUM>, which is coupled to the guide <NUM> in a sliding manner, and a rolling bearing <NUM>, which is interposed between the platform <NUM> and the slider <NUM> so as to allow the platform <NUM> and the slider <NUM> to rotate relative to one another around a rotation axis <NUM>, which is parallel to the direction <NUM>.

The platform <NUM> supports a plurality of motor-driven conveyor rollers <NUM> (in this case, five rollers <NUM>), which are aligned with one another, face the path P and laterally delimit the channel <NUM>. One of the rollers <NUM> (hereinafter indicated with 45a) is an input roller mounted so as to rotate around the axis <NUM> and the other rollers <NUM> (hereinafter indicated with 45b) are mounted so as to rotate around respective rotation axes <NUM>, which are parallel to one another and to the direction <NUM>.

The assembly <NUM> is integral to the slide <NUM> in the direction <NUM> and is mounted downstream of the limit stop device <NUM> in the direction <NUM>.

The assembly <NUM> is provided with a rotary platform <NUM>, which is coupled to the slide <NUM> in a rotary manner so as to rotate, relative to the slide <NUM>, around a fulcrum axis <NUM>, which is parallel to the direction <NUM> and is obtained at the entrance of the components <NUM> into the unit <NUM> and into the channel <NUM>.

The platform <NUM> is connected to the slide <NUM> through the interposition, in particular, of a shock absorber device <NUM>, which is completely equivalent to the device <NUM>, and of four coupling devices <NUM>, which are completely equivalent to the devices <NUM>.

The platform <NUM> supports a plurality of motor-driven conveyor rollers <NUM> (in this case, three rollers <NUM>), which are aligned with one another, face the path P and laterally delimit the channel <NUM>. One of the rollers <NUM> (hereinafter indicated with 51a) is an input roller mounted so as to rotate around the axis <NUM> and the other rollers <NUM> (hereinafter indicated with 51b) are mounted so as to rotate around respective rotation axes <NUM>, which are parallel to the direction <NUM>.

According to <FIG>, the assembly <NUM> is further provided with a sanding device <NUM> comprising three pulleys <NUM>, which are mounted on the platform <NUM> with a triangle-like arrangement and are coupled to the platform <NUM> so as to rotate, relative to the platform <NUM>, around respective rotation axes <NUM>, which are parallel to one another and to the direction <NUM>.

Two pulleys <NUM> (hereinafter indicated with 54a) are motor-driven drive rollers, which are mounted between the rollers 51b and are moved around the relative axes <NUM> by an operating device <NUM> comprising an electric motor <NUM>, which is mounted on the platform <NUM>, and a belt transmission <NUM>, which is interposed between the motor <NUM> and the pulleys 54a.

The third pulley <NUM> (hereinafter indicated with 54b) is a stretching roller, which is coupled to the platform <NUM> in a sliding manner so as to move crosswise to the relative axis <NUM> and stretch an abrasive belt <NUM> wound around the pulleys 54a, 54b in a ring shape.

The belt <NUM> is caused to come into contact with the relative face <NUM> to be sanded - and held there - by a pushing roller <NUM>, which is mounted between the pulleys 54a so as to rotate around a longitudinal axis <NUM> of its parallel to the axes <NUM> and, furthermore, is movable around a rotation axis (which is not shown herein), which is eccentric relative to the axis <NUM>, from and to an operating position, in which the roller <NUM> pushes the belt <NUM> against the relative face <NUM>.

The device <NUM> further comprises a synchronizing roller <NUM>, which is arranged within the belt <NUM> and is mounted so as to rotate around a longitudinal axis <NUM> of its, which is parallel to the axes <NUM>, <NUM>.

When the roller <NUM> is in its operating position, the roller <NUM> is moved crosswise to the axis <NUM>, due to the thrust of a pneumatic operating device <NUM>, so as to come into contact with the roller <NUM> and with one of the pulleys 54a in order to synchronize the peripheral speeds of the pulleys 54a and of the roller <NUM> and avoid friction of the belt <NUM> on the roller <NUM>.

The unit <NUM> is completely similar to the unit <NUM> and the only difference from the unit <NUM> lies in the fact that:.

In use, the component <NUM> is caused to come into contact with the limit stop device <NUM> and, then, is moved by the roller conveyor device <NUM> and by the conveyor assemblies <NUM>, <NUM> of the operating units <NUM>, <NUM> in the direction <NUM> and along the path P.

The sanding machine <NUM> has two operating modes of the operating units <NUM>, <NUM> depending on the profile of the side faces <NUM> of each component <NUM>.

According to a first operating mode, when the faces <NUM> of the component <NUM> are flat:.

In this way, the rollers 45a, 45b of the unit <NUM> and the rollers 51a, 51b of the unit <NUM> are aligned with one another in the direction <NUM>, the rollers 51a, 51b of the unit <NUM> and the rollers 45a, 45b of the unit <NUM> are aligned with one another and with the limit stop device <NUM> in the direction <NUM> and the feeding channel <NUM> has a constant width, which is equal to the width of the component <NUM>.

The cylinders <NUM> fixed to the slides <NUM> of the two units <NUM>, <NUM> are supplied with a pressure which, in any case, is smaller than the thrust exerted by the component <NUM> upon the assemblies <NUM>, <NUM> of the two units <NUM>, <NUM> so as to make up for possible changes in the shape of the faces <NUM> of the component <NUM>.

The cylinders <NUM> of the shock absorber devices <NUM> of the two units <NUM>, <NUM> are supplied with a pressure which, in any case, is smaller than the thrust exerted by the component <NUM> upon the assemblies <NUM>, <NUM> of the two units <NUM>, <NUM> so as to make up for possible changes in the width of the component <NUM> due to production size tolerances.

According to the other one of the two operating modes mentioned above, when the two faces <NUM> of the component <NUM> are not flat and have a curved profile:.

In this way, the slide <NUM> and, hence, the assemblies <NUM>, <NUM> of each unit <NUM>, <NUM> are movable in the direction <NUM> depending on the profile of the faces <NUM> of the component <NUM> and the platforms <NUM>, <NUM> and, hence, the assemblies <NUM>, <NUM> of each unit <NUM>, <NUM> are movable around the relative fulcrum axes <NUM>, <NUM> depending on the profile of the faces <NUM> of the component <NUM>.

With reference to what described above, it should be pointed out that:.

When the faces <NUM>, <NUM> and <NUM> are connected to one another by means of relative bevelled edges <NUM> (<FIG>), the path P extends through two further operating units, one of them (hereinafter indicated with <NUM>) being shown in <FIG> and <FIG> and being configured to sand the bottom left edge <NUM> and the top right edge <NUM> and the other one (which is not shown herein) being configured to sand the bottom right edge <NUM> and the top left edge <NUM>.

The unit <NUM> comprises a frame <NUM>, an intermediate slide <NUM> and a shock absorber device <NUM>, which are completely equivalent to the frame <NUM>, to the intermediate slide <NUM> and to the shock absorber device <NUM> of the units <NUM>, <NUM>.

The slide <NUM> supports two conveyor assemblies <NUM>, <NUM> arranged on opposite sides of the path P in the direction <NUM>.

The assembly <NUM> is integral to the slide <NUM> in the direction <NUM>, is aligned with the limit stop device <NUM> in the direction <NUM> and is provided with a vertical upright <NUM> projecting upwards from the slide <NUM> in the direction <NUM>.

The upright <NUM> supports a plurality of motor-driven conveyor rollers <NUM> (in particular, two rollers <NUM>), which are aligned with one another and with the device <NUM> in the direction <NUM>, face the path P, laterally delimit the channel <NUM> and are mounted so as to rotate around respective rotation axes <NUM>, which are parallel to the direction <NUM>.

With reference to <FIG>, the assembly <NUM> further comprises a sanding device <NUM> provided with a first support plate <NUM>, which is mounted on the upright <NUM> and is inclined relative to the surface A so as to be substantially perpendicular to the relative edge <NUM>, with a second support plate <NUM>, which is coupled to the plate <NUM> in a sliding manner so as to move, relative to the plate <NUM>, in the direction <NUM>, and with a bracket <NUM>, which is coupled to the plate <NUM> in a rotary manner so as to rotate, relative to the plate <NUM> and due to the thrust of an operating device <NUM>, which is better described below, with an oscillatory reciprocating motion around a fulcrum axis <NUM>, which is parallel to the plate <NUM>.

The device <NUM> has three pulleys <NUM>, which are mounted on the plate <NUM> with a triangle-like arrangement, and an abrasive belt <NUM> wound around the pulleys <NUM> in a ring shape.

A first pulley <NUM> (hereinafter indicated with 81a) is a motor-driven roller mounted on the plate <NUM> so as to rotate around a longitudinal axis <NUM> of its, which is perpendicular to the plate <NUM>, due to the thrust of an operating device <NUM> comprising an electric motor <NUM>, which is fixed to the plate <NUM>, and a belt transmission <NUM>, which is interposed between the roller 81a and the motor <NUM>.

A second pulley <NUM> (hereinafter indicated with 81b) is a stretching roller, which is mounted on the plate <NUM> so as to rotate around a longitudinal axis <NUM> of its parallel to the axis <NUM> and is moved by the plate <NUM> in the direction <NUM> so as to stretch the belt <NUM>.

A third pulley <NUM> (hereinafter indicated with 81c) is mounted on the bracket <NUM> so as to rotate around a longitudinal axis <NUM> of its, whose orientation depends on the position of the bracket <NUM> around the axis <NUM>.

The oscillatory reciprocating motion of the bracket <NUM> and, hence, of the pulley 81c around the axis <NUM> generates a straight reciprocating motion of the belt <NUM> along the pulleys 81a, 81b, 81c and, hence, a relatively even wear of the belt <NUM>.

According to <FIG>, the device <NUM> comprises a reduction unit <NUM>, which is fixed to the bracket <NUM> and has an input shaft <NUM>, which is mounted so as to rotate around a longitudinal axis <NUM> of its parallel to the axis <NUM> and is connected to the pulley 81c through the interposition of a belt transmission <NUM>.

The reduction unit <NUM> is further provided with an output shaft <NUM> comprising a first portion <NUM>, which is coupled to the shaft <NUM> so as to rotate around a longitudinal axis <NUM> of its transverse to the axis <NUM>, and a second portion <NUM>, which has a longitudinal axis <NUM> parallel to the axis <NUM>, is coupled to the portion <NUM> in an angularly fixed manner ans is further coupled to the portion <NUM> in a sliding manner so as to be moved, during a set-up phase for setting up the sanding device <NUM>, crosswise to the axis <NUM>.

The portion <NUM> is axially locked on the portion <NUM> by means of a fastening screw (not shown herein), which extends through a slot <NUM> obtained in the portion <NUM>, is screwed into the portion <NUM> and allows the eccentricity of the axis <NUM> relative to the axis <NUM> to be selectively controlled.

The portion <NUM> is engaged in a rotary manner, through the interposition of a rolling ball bearing which is not shown herein, through a first free end of a connecting rod <NUM>, whose second free end is connected, through the interposition of a ball joint which is not shown herein, to a coupling pin <NUM>, which projects, crosswise to the axis <NUM>, from a support bracket <NUM> fixed to the plate <NUM> perpendicularly to the plate <NUM>.

In use, the rotary motion of the pulley 81c around the axis <NUM> is transmitted by the belt transmission <NUM>, first of all, to the input shaft <NUM> and, then, to the output shaft <NUM> of the reduction unit <NUM> so as to move the portion <NUM> around the axis <NUM> and the portion <NUM> around the axis <NUM>.

Since the portion <NUM> is engaged through the connecting rod <NUM>, which, in turn, is connected to the bracket <NUM> and, hence, to the plate <NUM>, the portion <NUM> is caused to rotate around the eccentric axis <NUM>, thus generating the oscillatory reciprocating motion of the bracket <NUM> around the axis <NUM>.

The oscillatory reciprocating motion of the pulley 81a around the axis <NUM> generates a straight reciprocating motion of the belt <NUM> along the pulleys 81a, 81b, 81c parallel to the relative axes <NUM>, <NUM>, <NUM> and a substantially even wear of the belt <NUM> over a relatively large width of the belt <NUM>.

The straight reciprocating motion of the belt <NUM> along the pulleys 81a, 81b, 81c has a back stroke and a forth stroke, which are independent of the speed of movement of the belt <NUM> around the pulleys 81a, 81b, 81c, depend on the width of the oscillation of the bracket <NUM> around the axis <NUM> and, hence, on the eccentricity between the axes <NUM> and <NUM> and are selectively controlled by changing the eccentricity between the axes <NUM> and <NUM>.

The device <NUM> further comprises a pushing element <NUM>, which is mounted between the pulleys 81b and 81c and is movable, due to the thrust of a pneumatic actuator cylinder <NUM> fixed to the plate <NUM>, between a forward operating position, in which the element <NUM> causes the belt <NUM> to come into contact with the relative edge <NUM>, and a retracted rest position, in which the belt <NUM> disengages the edge <NUM>.

With reference to <FIG> and <FIG>, the assembly <NUM> is arranged on the side of the path P opposite the one of the device <NUM> and comprises a horizontal slide <NUM>, which is mounted on the slide <NUM> and is coupled to the slide <NUM> in a sliding manner so as to make straight movements along the slide <NUM> in the direction <NUM> due to the thrust of an operating device, which is completely equivalent to the operating device <NUM>, and through the interposition of a shock absorber device, which is completely equivalent to the shock absorber device <NUM>.

The slide <NUM> extends upwards in the direction <NUM> and supports a plurality of motor-driven conveyor rollers <NUM> (in particular, two rollers <NUM>), which are aligned with one another in the direction <NUM>, face the path P, laterally delimit the channel <NUM> and are mounted so as to rotate around respective rotation axes <NUM>, which are parallel to the direction <NUM>.

The slide <NUM> is engaged in a sliding manner by a vertical slide <NUM>, which, during a set-up phase for setting up the assembly <NUM>, is moved by an operating device <NUM> along the slide <NUM> in the direction <NUM> depending on a height of the component <NUM>.

The slide <NUM> supports a sanding device <NUM>, which is completely equivalent to the sanding device <NUM> and is hinged to the slide <NUM> so as to rotate, relative to the slide <NUM> and due to the thrust of a pair of actuator cylinders <NUM>, around a fulcrum axis <NUM>, which is substantially parallel to the direction <NUM>, between an operating position, in which the device <NUM> sands the relative edge <NUM>, and a rest position, which is suited to allow the belt <NUM> to be replaced.

The operating unit (not shown) mounted downstream of the unit <NUM> in the direction <NUM> is completely equivalent to the unit <NUM> and the only difference from the unit <NUM> lies in the fact that:.

Claim 1:
A sanding machine for sanding/finishing/brushing components (<NUM>) made of wood, metal or the like; the sanding machine comprising at least one sanding unit (<NUM>) for sanding/finishing the component (<NUM>); and a feeding device (<NUM>), which defines a support surface (A) for at least one component (<NUM>) and is designed to feed the component (<NUM>) in a first direction (<NUM>), which is parallel to the support surface (A), and along a path (P) extending through the sanding unit (<NUM>); the sanding unit (<NUM>) comprising a frame (<NUM>), at least two pulleys (81a, 81b, 81c), which are mounted so as to rotate around respective longitudinal axes (<NUM>, <NUM>, <NUM>), an abrasive belt (<NUM>), which is wound in a ring shape around the pulleys (81a, 81b, 81c), and an operating device (<NUM>) to move a first pulley (81c) with an oscillatory reciprocating motion around a rotation axis (<NUM>), which is transverse to the relative longitudinal axis (<NUM>); the operating device (<NUM>) comprising two transmission shafts (<NUM>, <NUM>), which are coupled to one another in an angularly fixed manner so as to rotate around respective longitudinal axes (<NUM>, <NUM>), which are eccentric to one another, a first transmission system (<NUM>, <NUM>) to connect a first transmission shaft (<NUM>) and the first pulley (81c) to one another, and a second transmission system (<NUM>, <NUM>) to connect a second transmission shaft (<NUM>) and the frame (<NUM>) to one another; and being characterized in that the transmission shafts (<NUM>, <NUM>) are coupled so as to radially move relative to one another and selectively control the eccentricity between the relative longitudinal axes (<NUM>, <NUM>) .