Patent Description:
When dealing with the sanding/finishing of panels made of wood, metal, plastic or the like, a sanding machine, as for example disclosed in document <CIT>, is known, which comprises a conveyor belt, which has an upper transport branch defining a substantially horizontal support surface for at least one panel and is designed to feed the panel in a first direction; and a sanding device, which is mounted above the support surface in order to sand an upper face of the panel.

The sanding device comprises an abrasive belt, which is wound in a ring shape around a plurality of idler rollers and extends in a second direction, which is transverse to the first direction.

The sanding device further comprises a plurality of thrust elements, which are distributed inside the abrasive belt in a third direction, which is inclined at angles other than <NUM>° relative to the first direction and to the second direction, and have an active portion with a substantially rectangular shape acting upon the abrasive belt.

The thrust elements are movable independently of one another in a fourth direction, which is orthogonal to the support surface, between respective lowered operating positions, in which the corresponding portions of abrasive belt are moved so as to come into contact with the upper face of the panel, and respective raised rest position, in which the corresponding portions of abrasive belt disengage the upper portion of the panel.

Generally speaking, the sanding machine further comprises an intermediate belt interposed between the thrust element and the abrasive belt.

The intermediate belt is mounted inside the abrasive belt and is provided with a plurality of teeth, which project from the intermediate belt, are in contact with the abrasive belt in order to the reduce the surface of the abrasive belt in contact with the panel and define, together with the abrasive belt, a plurality of cooling channels, which are flown through by air suited to ensure the cooling of the abrasive belt.

The sanding machine is further provided with a detection device to detect at least one geometrical feature of the panel.

The detection device normally comprises a plurality of contact rollers, which are distributed above the support surface in the second direction and are mounted so as to rotate around respective rotation axes, which are parallel to the second direction.

Following the movement of the panel in the first direction, the contact rollers arranged inside the moving path of the panel are lifted from the panel so as to allow the detection device to detect the width of the panel in the second direction and/or the presence of possible openings made in panels used as, for example, frames for doors and/or windows.

Since the thrust elements are distributed in the third direction, the active portion of each thrust element has a width, measured parallel to the third direction, which is smaller than a width, measured parallel to the second direction, of the portion of abrasive belt and, hence, of panel engaged by the active portion.

As a consequence, known sanding machines for sanding/finishing of panels made of wood, metal, plastic or the like of the type described above suffer from a relatively small processing precision, in particular in the area of the longitudinal edges of the upper face of the panel parallel to the first direction.

As a consequence, known sanding machines for sanding/finishing of panels made of wood, metal, plastic or the like of the type described above must be provided with an electronic control unit, which is configured to calculate the aforesaid time intervals and, therefore, is relatively complicated and expensive.

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

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

With reference to <FIG>, number <NUM> indicates, as a whole, a sanding machine for sanding/finishing panels <NUM> made of wood, metal, plastic or the like with a substantially parallelepiped-like shape.

According to a variant which is not shown herein, the panel <NUM> has at least one opening and is used, for example, as frame for doors and/or windows.

The sanding machine <NUM> comprises a support frame <NUM> and a feeding device <NUM>, which is mounted on the support frame <NUM> so as to move the panels <NUM> one after the other in a horizontal direction <NUM>.

The device <NUM> comprises a conveyor belt <NUM>, which has an upper transport branch defining a horizontal support surface P for the panel <NUM> and is wound in a ring shape around a pair of motor-driven pulleys <NUM> so as to rotate, relative to the frame <NUM>, around respective longitudinal axes <NUM>, which are parallel to one another and to a horizontal direction <NUM>, which is transverse to the direction <NUM>.

According to a variant which is not shown herein, the conveyor belt <NUM> is eliminated and replaced by a plurality of motor-driven feeding rollers, which are mounted so as to rotate around respective rotation axes, which are parallel to the axis <NUM>.

The sanding machine <NUM> further comprises at least one sanding unit <NUM> comprising, in turn, an abrasive belt <NUM>, which is wound in a ring shape around a plurality of idler rollers <NUM> (in this case, two rollers <NUM>), which are mounted so as to rotate around respective longitudinal axes <NUM> parallel to a direction <NUM>, which is oriented according to respective angles other than <NUM>° relative to the direction <NUM> and to the direction <NUM>.

The belt <NUM> has a lower sanding branch <NUM>, which is moved so as to come into contact with an upper face <NUM> of the panel <NUM> in ways that will be better described below and extends as well as is movable in a direction <NUM>, which is transverse to the direction <NUM> and is oriented according to respective angles other than <NUM>° relative to the direction <NUM> and to the direction <NUM>.

The unit <NUM> further comprises an intermediate belt <NUM>, which is mounted inside the belt <NUM>, extends as well as is movable in the direction <NUM> and is wound in a ring shape around a plurality of idler rollers <NUM> (in this case, two rollers <NUM>), which are mounted so as to rotate around respective longitudinal axes <NUM>, which are parallel to the axes <NUM> and to the direction <NUM>.

The belt <NUM> has a plurality of teeth <NUM> parallel to one another, which project from an outer surface of the belt <NUM> and face the belt <NUM>.

The belts <NUM> and <NUM> are operated by an operating device <NUM> comprising, in this case, an electric motor (which is not shown herein), a first belt transmission <NUM> to connect an output rod of the electric motor (which is not shown herein) and one of the rollers <NUM> to one another and a second belt transmission <NUM> to connect the motor-driven roller <NUM> and one of the rollers <NUM> to one another.

The lower branch <NUM> of the belt <NUM> is selectively moved so as to come into contact with the face <NUM> of the panel <NUM> by a thrust device <NUM>, which is mounted inside the belt <NUM>.

The device <NUM> comprises, in particular, a plurality of thrust elements <NUM>, which are distributed inside the belt <NUM> in the direction <NUM>, are mounted above the branch <NUM> and are movable independently of one another in a vertical direction <NUM>, which is orthogonal to the directions <NUM> and <NUM> and perpendicular to the surface P.

Each element <NUM> has an active portion (which is not shown herein) with a substantially rectangular shape and is movable in the direction <NUM> between a lowered operating position, in which the active portion of the element <NUM> moves the belt <NUM> so that it comes into contact with the belt <NUM> and the belt <NUM> so that it comes into contact with the face <NUM>, and a raised rest position, in which the belt <NUM> disengages the face <NUM>.

Following the movement of the elements <NUM> to their lowered operating position, the teeth <NUM> of the belt <NUM> are moved so as to come into contact with the belt <NUM> in order to reduce the surface of the belt <NUM> in contact with the face <NUM> and define, together with the belt <NUM>, a plurality of cooling channels (not shown herein), which are flown through by air suited to ensure the cooling of the belt <NUM>.

With regard to the information disclosed above, it should be pointed out that the width of the belt <NUM>, measured parallel to the direction <NUM>, is at least equal to twice the width of the active portion (not shown herein) of an element <NUM> measured parallel to the direction <NUM>.

The sanding machine <NUM> is further provided with a detection device <NUM>, which is mounted above and on the input side of the surface P in order to detect at least one geometrical feature of the panel <NUM>.

In this case, the device <NUM> is a mechanical detection device, which is arranged upstream of the device <NUM> in the direction <NUM> and comprises a plurality of contact rollers <NUM>, which are as many as the elements <NUM>.

The rollers <NUM> are distributed above the surface P in the direction <NUM> and are mounted so as to rotate around respective rotation axes <NUM>, which are parallel to the direction <NUM>.

Following the movement of the panel <NUM> in the direction <NUM>, the contact rollers <NUM> arranged inside the moving path of the panel <NUM> are lifted from the panel <NUM> so as to allow the detection device <NUM> to detect the width of the panel <NUM> in the direction <NUM> and/or the presence of openings (not shown herein) made in the panels <NUM> used as, for example, frames for doors and/or windows.

Each element <NUM> is aligned with a corresponding roller <NUM> in the direction <NUM> and is associated with the corresponding roller <NUM> so as to move between its lowered operating position and its raised rest position in response to a signal of the roller <NUM>.

According to a variant which is not shown herein, the rollers <NUM> are eliminated and replaced by at least one detection device that is not in contact with the panels <NUM>, for example an optical, inductive or capacitive device.

Since the elements <NUM> are distributed in the direction <NUM>, the active portion (which is not shown herein) of each element <NUM> has a width, measured parallel to the direction <NUM>, which is equal to a width, also measured parallel to the direction <NUM>, of the portion of belt <NUM> and, hence, of panel <NUM> engaged by the active portion itself (which is not shown herein) and the sanding machine <NUM> has a relatively high processing precision, in particular in the area of the longitudinal edges of the face <NUM> parallel to the direction <NUM>.

Furthermore, since both the elements <NUM> and the rollers <NUM> are distributed above the surface P in the direction <NUM>, both the distances between the elements <NUM> and the relative rollers <NUM> and the time intervals between the detection of the rollers <NUM> and the movements of the corresponding elements <NUM> to their lowered operating positions are equal to one another.

As a consequence, the sanding machine <NUM> is provided with an electronic control unit <NUM>, which is configured to calculate one single time interval and, therefore, is relatively simple and economic.

The variant shown in <FIG> is different from <FIG> in that, in the former, the sanding machine <NUM> comprises a further sanding unit <NUM>, which is arranged between the detection device <NUM> and the unit <NUM> and is completely equivalent to the unit <NUM>.

The sole difference between the unit <NUM> and the unit <NUM> lies in the fact that the branch <NUM> of the belt <NUM> of the unit <NUM> extends and is movable in a direction <NUM> converging towards the direction <NUM>.

In particular, the belt <NUM> of the unit <NUM> is movable in a clockwise direction and the belt <NUM> of the unit <NUM> is movable in a counterclockwise direction. As a consequence, both the direction <NUM> and the direction <NUM> have a component that is parallel and contrary to the direction <NUM> and the sanding processing of the belts <NUM> of the two units <NUM> and <NUM> is oriented substantially crosswise to the direction <NUM>.

The variant shown in <FIG> is different from <FIG> in that, in the former, the branch <NUM> of the belt <NUM> of the unit <NUM> extends and is movable in a direction <NUM> parallel to the direction <NUM>.

In particular, the belt <NUM> of the unit <NUM> is movable in a clockwise direction and the belt <NUM> of the unit <NUM> is movable in a counterclockwise direction. As a consequence, the direction <NUM> has a component that is parallel and contrary to the direction <NUM>, the direction <NUM> has a component that is parallel to and concordant with the direction <NUM>, the sanding processing of the belt <NUM> of the unit <NUM> is oriented substantially crosswise to the direction <NUM>, the sanding processing of the belt <NUM> of the unit <NUM> is oriented according to a relatively large angle relative to the direction <NUM> and, therefore, the sanding machine <NUM> has a relatively high finishing of the faces <NUM> of the panels <NUM>.

Claim 1:
A sanding machine for sanding/finishing panels (<NUM>) made of wood, metal, plastic or the like, the sanding machine comprising a feeding device (<NUM>), which defines a support surface (P) for at least one panel (<NUM>) and is designed to feed the panel (<NUM>) in a first direction (<NUM>); at least one first sanding device (<NUM>), which is mounted above or under the support surface (P) and comprises, in turn, a first abrasive belt (<NUM>), which is wound in a ring shape around a plurality of idler rollers (<NUM>) so as to sand a face (<NUM>) of the panel (<NUM>); a plurality of first thrust elements (<NUM>), which are distributed inside the first abrasive belt (<NUM>) in a second direction (<NUM>), which is transverse to the first direction (<NUM>) and parallel to the support surface (P); and a detection unit (<NUM>), which is mounted upstream of the first thrust elements (<NUM>) in the first direction (<NUM>) in order to detect at least one geometrical feature of the panel (<NUM>), and comprises a plurality of detection devices (<NUM>), which are present in a number that is the same as the number of the first thrust elements (<NUM>) and are aligned with one another in the second direction (<NUM>); and being characterized in that the first abrasive belt (<NUM>) has a sanding segment (<NUM>), which is in contact with the face (<NUM>) and extends as well as is movable in a third direction (<NUM>), which is parallel to the support surface (P) and is inclined at angles other than <NUM>° relative to said first and second directions (<NUM>, <NUM>).