SANDING MACHINE FOR SANDING/FINISHING PANELS MADE OF WOOD, METAL OR THE LIKE

Abstract

 In a sanding machine for sanding/finishing panels (2) made of wood, metal or the like, an abrasive belt (11) is moved in contact with a panel (2) by a plurality of thrust elements (20) which are distributed within the abrasive belt (11) and are moved perpendicularly to the panel (2) by respective actuator cylinders (22), each of which has an output rod (28) movable under the thrust of a pressurized gas selectively fed into two chambers (31, 32) from a single supply manifold (34); each chamber (31, 32) communicating with an outlet (39) of the pressurized gas into the external environment.

Description

[0001] The present invention relates to a sanding machine for sanding/finishing panels of wood or the like.

[0002] In the field of sanding/finishing panels of wood, metal or the like, it is known to manufacture a sanding machine of the type comprising a conveyor belt having an upper conveying branch defining a substantially horizontal support plane for at least one panel, and being designed to feed the panel in a given first direction; a sanding device mounted above the support plane and comprising, in turn, an abrasive belt wound in a ring shape around a plurality of idler rollers for sanding an upper face of the panel; and a detection device for detecting a width of the panel in a second direction parallel to the support plane and transverse to the first direction.

[0003] The sanding machine also comprises a plurality of thrust elements, which are distributed within the abrasive belt in the second direction, and are movable independently from each other in a third direction orthogonal to the support plane between respective lowered operating positions, where the corresponding portions of the abrasive belt come into contact with the upper face of the panel, and respective raised rest positions.

[0004] The thrust elements are fixed to the output rods of respective pneumatic actuator cylinders, and are selectively moved into their lowered operating positions according to the width of the panel.

[0005] The output rod of each actuator cylinder is slidingly engaged in a cylinder formed through a containing casing of the actuator cylinder, and is configured so as to divide the cylinder into an upper chamber and a lower chamber connected with respectively independent pneumatic feeding devices.

[0006] To check the operation of each actuator cylinder with only one valve and to avoid mounting two valves on each actuator cylinder, the lower chamber, responsible for moving the thrust element from the lowered operating position to the raised rest position, is kept constantly under pressure, while the upper chamber, responsible for moving the thrust element from the raised rest position to the lowered operating position, is selectively fed with a pressurized gas capable of exerting on the thrust element a downward force greater than the upward force exerted on the thrust element by the pressure in the lower chamber.

[0007] Consequently, during the sanding step, the abrasive belt is kept in contact with the panels by the pressure in the upper chambers of the actuator cylinders each time involved, namely by a pressure higher than the one in the lower chambers of the actuator cylinders.

[0008] The aforesaid known sanding machines have some drawbacks, mainly deriving from the fact that the abrasive belt is kept in contact with the panels by a relatively high pressure, which is higher than the pressure strictly necessary to ensure a proper functioning of the sanding device according to the profile of the upper faces of the panels, and may, therefore, damage the panels.

[0009] The object of the present invention is to provide a sanding machine for sanding/finishing panels of wood, metal or the like which is free from the aforesaid drawbacks and which is simple and cheap to implement.

[0010] According to the present invention, it is provided a sanding machine for sanding/finishing panels of wood, metal or the like as claimed in the appended claims.

[0011] The present invention will now be described with reference to the accompanying drawings which illustrate a non-limitative embodiment, in which:

Figure 1 is a schematic perspective view, with parts removed for clarity's sake, of a preferred embodiment of the sanding machine of the present invention; and

Figure 2 is a schematic longitudinal section of a detail of the sanding machine of Figure 1.

[0012] With reference to Figure 1, 1 indicates, as a whole, a sanding machine for sanding/finishing panels 2 of wood, metal or the like, having a substantially parallelepiped shape.

[0013] The sanding machine 1 comprises a support frame 3, and a feeding device 4 mounted on the frame 3 for successively feeding the panels 2 in a horizontal direction 5.

[0014] The device 4 comprises a conveyor belt 6, which has an upper conveying branch defining a horizontal support plane P for the panels 2, and is wound in a ring shape around a pair of motorized pulleys 7 mounted to rotate, with respect to the frame 3, around respective longitudinal axes 8 parallel to each other and to a horizontal direction 9 transverse to the direction 5.

[0015] The sanding machine 1 further comprises a sanding unit 10 comprising, in turn, an abrasive belt 11 wound in a ring shape around a plurality of idler rollers 12 (in this case three rollers 12), which are mounted to rotate around respective longitudinal axes 13 parallel to the direction 9, and are arranged so as to give to the belt 11 a cross-section having a substantially triangular shape.

[0016] In particular, the arrangement of the rollers 12 is such that the tape 11 has a lower branch 14 substantially plane and parallel to the plane P.

[0017] The sanding machine 1 comprises a detection device 15 mounted above and at the entrance of the plane P for detecting a width of the panel 2 in the direction 9.

[0018] In the present case, the device 15 is a mechanical detection device comprising a plurality of contact rollers 16, which are distributed above the plane P in the direction 9, and are mounted to rotate around respective rotation axes 17 parallel to the direction 9.

[0019] Following the advancement of the panel 2 in the direction 5, the rollers 16 arranged inside the feed path of the panel 2 are lifted from the panel 2 so as to allow the device 15 to detect the width of the panel 2 in the direction 9.

[0020] According to a variant not illustrated, the rollers 16 are removed and replaced with an optical detection device.

[0021] The lower branch 14 of the belt 11 is selectively brought into contact with an upper face 18 of the panels 2 by a thrust device 19 mounted inside the tape 11.

[0022] The device 19 comprises, in this case, a plurality of thrust elements 20 which are distributed inside the tape 11 in the direction 9, are mounted above the branch 14, and are independently movable in a vertical direction 21, orthogonal to the directions 5 and 9 and perpendicular to the plane P.

[0023] Each element 20 is movable in the direction 21 between a lowered operating position, in which the corresponding portion of the tape 11 is moved in contact with the face 18, and a raised rest position.

[0024] As shown in Figure 2, each element 20 is moved between its lowered operating position and its raised rest position by a relative actuator cylinder 22 comprising a containing casing 23 and a cylinder 24, which is formed through the casing 23, has a substantially vertical longitudinal axis 25 and comprises an upper widened portion 26 and a lower narrowed portion 27.

[0025] The element 20 has the shape of a plate fixed to the free end of an output rod 28 of the actuator cylinder 22, transverse to the axis 25, and is coupled in a sliding and angularly fixed way to the casing 23 through a coupling pin 29 projecting upwardly from the element 20 parallel to the direction 21.

[0026] The rod 28 is slidingly engaged in the portion 27 coaxially with the axis 25, projects downwardly from the casing 23 in the direction 21, and is substantially fluid-tight coupled to the portion 27.

[0027] The rod 28 is provided with a plate 30, which extends transversely to the axis 25, is slidingly engaged in the portion 26, and divides the cylinder 24 into an upper chamber 31 and a lower chamber 32.

[0028] The two chambers 31, 32 are connected with a pneumatic feeding unit 33 comprising a single supply manifold 34 which is formed through the casing 23 and is selectively connectable with a first pneumatic circuit 35 formed through the casing 23 to feed a pressurized gas to the chamber 31 and with a second pneumatic circuit 36 formed through the casing 23 to feed a pressurized gas to the chamber 32.

[0029] The manifold 34 is selectively connected with the two circuits 35, 36 via a valve 37 comprising a switching member 38 mobile between a first operating position, in which the manifold 34 is connected with the chamber 31, and a second operating position, in which the manifold 34 is connected with the chamber 32.

[0030] Each circuit 35, 36 is further connected in a continuous manner with the outside of the casing 23, in particular with the external environment, through an outlet 39 of the actuator cylinder 22 for the pressurized gas.

[0031] In the present case, each outlet 39 is defined by a calibrated bore 40 formed through a sleeve 41 screwed into the casing 23.

[0032] According to a variant not illustrated, each calibrated bore 40 is formed directly through the casing 23.

[0033] The two bores 40 have respectively different passage cross-sections. In particular, the bore 40 associated with the circuit 35 has a passage cross-section larger than the passage cross-section of the bore 40 associated with the circuit 36.

[0034] The plate 30 is slidingly coupled to the portion 26 through the interposition of an annular lip gasket 42 mounted on the plate 30 so as to radially contract under the thrust of the pressurized gas supplied to the chamber 31 and to radially expand under the thrust of the pressurized gas supplied to the chamber 32.

[0035] In use, the pressurized gas fed along the manifold 34 is selectively sent through the valve 37 to the chamber 31 to move the thrust element 20 in its lowered operating position and to the chamber 32 to move the thrust element 20 in its raised rest position.

[0036] When the pressurized gas is supplied to the chamber 31 and the thrust element 20 is moved into its lowered operating position:

the pressurized gas contained in chamber 32 is partly discharged through the relative calibrated bore 40 and partly discharged along the lower narrowed portion 27 of the cylinder 24 because of the leaks existing between the cylinder 24 and the rod 28; and

the gasket 42 radially contracts.

[0037] Consequently, the friction between the cylinder 24 and the output rod 28 is reduced by improving the smoothness of the output rod 28.

[0038] When the pressurized gas is fed into the chamber 32 and the thrust element 20 is moved into its raised rest position, the pressurized gas contained in chamber 31 is at least partly discharged through the relative calibrated bore 40. From the aforesaid it is clear that the thrust elements 20 are moved in contact with the abrasive belt 11 and the abrasive belt 11 is kept in contact with the upper face 18 of the panel 2 with a relatively reduced pressure, equal to, and therefore not higher than, the pressure of the gas fed into the chamber 32 to move the thrust element 20 in its raised rest position.

Claims

1. A sanding machine for sanding/finishing panels (2) made of wood, metal or the like comprising a feeding device (4), which defines a support surface (P) for at least one panel (2) and is designed to feed the panel (2) in a first direction (5); a sanding device (10), which is mounted above the support surface (P) and comprises, in turn, an abrasive belt (11) which is wound in a ring shape around a plurality of idler rollers (12) so as to sand an upper face (18) of the panel (2); a plurality of thrust elements (20), which are distributed inside the abrasive belt (11) in a second direction (9), which is transverse to the first direction (5) and parallel to the support surface (P); and, for each thrust element (20), a respective actuator cylinder (22) to move the thrust element (20) between a lowered operating position, in which the thrust element (20) moves the abrasive belt (11) so as to cause it to come into contact with the upper face (18) of the panel (2), and a raised rest position; each actuator cylinder (22) comprising a containing casing (23), a cylinder (24), which is obtained in the containing casing (23), an output rod (28), which is slidingly engaged in the cylinder (24) and is configured to divide the cylinder (24) into two chambers (31, 32), and a pneumatic unit (33) to feed a pressurized gas into the chambers (31, 32); and characterized in that the pneumatic unit (33) comprises a single supply manifold (34), a valve device (37) to selectively connect the supply manifold (34) to said chambers (31, 32), and, for each chamber (31, 32), a respective outlet (39) to drain at least part of the pressurized gas contained in the chamber (31, 32) to the outside of the containing casing (23), in particular into the external environment.

2. A sanding machine according to claim 1, wherein each outlet (39) is configured so as to connect the relative chamber (31, 32) to the outside of the containing casing (23) in a continuous manner.

3. A sanding machine according to claim 1 or 2, wherein each outlet (39) is defined by a calibrated bore (40).

4. A sanding machine according to any of the previous claims, wherein the pneumatic unit (33) further comprises for each chamber (31, 32) a respective pneumatic circuit (35, 36) to connect the supply manifold (34) to the chamber (31, 32).

5. A sanding machine according to claim 4, wherein each outlet (39) is obtained along a relative pneumatic circuit (35, 36).

6. A sanding machine according to claim 4 or 5, wherein each outlet (39) is defined by a calibrated bore (40), which is pneumatically connected to a relative pneumatic circuit (35, 36) and, in particular, to the external environment.

7. A sanding machine according to any of the previous claims, wherein the valve device (37) comprises a switching member (38), which is mobile between a first operating position, in which the supply manifold (34) is connected to one of the two chambers (31, 32), and a second operating position, in which the supply manifold (34) is connected to the other chamber (31, 32).

8. A sanding machine according to any of the previous claims, wherein the output rod (28) is slidingly coupled to the cylinder (24) through the interposition of an annular gasket (42) which is fitted on the output rod (28).

9. A sanding machine according to claim 8, wherein the annular gasket (42) is a lip gasket which is mounted on the output rod (28) so as to radially contract under the thrust of the pressurized gas supplied to the chamber (31) that is responsible for the movement of the thrust element (20) from its raised rest position to its lowered operating position and so as to radially expand under the thrust of the pressurized supplied to the chamber (32) that is responsible for the movement of the thrust element (20) from its lowered operating position to its raised rest position.

10. A sanding machine according to any of the previous claims, wherein each thrust element (20) is fixed to a free end of the output rod (28) of the relative actuator cylinder (22).

11. A sanding machine according to any of the previous claims, wherein each thrust element (20) is coupled to the containing casing (23) of the relative actuator cylinder (22) in a sliding and angularly fixed manner.

Drawing