EP0365508A2

EP0365508A2 - Shuttering joist cleaning machine and system

Info

Publication number: EP0365508A2
Application number: EP89850356A
Authority: EP
Inventors: Tord Eriksson; Jan Thörnlund
Original assignee: Adema Maskin AB
Current assignee: Adema Maskin AB
Priority date: 1988-10-18
Filing date: 1989-10-18
Publication date: 1990-04-25
Also published as: SE468774B; NO894142L; SE8803717D0; EP0365508A3; SE8803717L; NO894142D0

Abstract

The invention relates to a machine and a system for cleaning wood shuttering joists in particular for removing residual concrete (2). The machine comprises an elongate frame (3) having a series of rollers (7) forming a roller conveyor. A number of driving stations (8, 10) advance the shuttering joist (1) along the roller conveyor. A cleaning station (9) is provided in the frame and is adapted to contact the opposite side surfaces of the shuttering joist so as to clean said surfaces. The characteristic features of the invention are that the cleaning station comprises two opposed, separately driven cylinders (14, 15) each having a hard structured surface for removing the concrete residuals by grinding, preferably milling. The system in accordance with the invention comprises the machine so modified that it comprises a load testing station for load testing the shuttering joists, a first transfer station for transferring the joists, one at a time, from the roller conveyor to a collecting table (56) on which the shuttering joists are collected beside each other to form av group, a second transfer station for transferring successive groups of shuttering joists to a lifting table (58) in such a manner that one layer of shuttering joists is placed upon the previous layer, and a bundling station for tying up a predetermined number of groups of shuttering joists on the lifting table with straps so as to form a package of treated shuttering joists.

Description

This invention relates to a machine and a system for cleaning shuttering joists of wood. In particular residual concrete, adhering to the side surfaces of a shuttering joist should be removed.
A common method to clean shuttering joist is to use a scraping iron or a wire brush and manually remove the concrete residuals sticking to the shuttering joists when the form has been stripped.
US-A-2 835 909 relates to a concrete form cleaning machine for cleaning the main surface and the edges of a concrete form of the panel type. The panel is inserted vertically between two guides. The panel is supported on a non-driven roller conveyor and is advanced through a cleaning station comprising stationary brushes. A conveyor chain is provided on one of the guides and serves as a driving dog for the panel. Said brushes will thus clean the surface of the panel. An additional rotating brush is cleaning the lower edge of the panel.
A drawback with this known device is that its cleaning efficiency is poor.
FR-A-1 134 990 relates to a machine for cleaing boards and cheese cloth used in the cheese industriy. The boards are advanced through the nip formed between a rotating brush and a stationary brush while at the same time the board is sprayed with a cleaning liquid housed in a container provided beneath the brushes. The board is advanced by the rotating brush itself, said brush having a rotational speed much higher than the speed by which the board is advanced.
This known machine is not adapted for cleaning boards to which concrete is sticking since its cleaning efficiency is poor. The presence of a liquid filled container will also complicate a field use of the machine at different working sites.
FR-A-2 281 475 relates to a panel cleaning machine, in particular to a machine for cleaning the main surfaces of a form panel to which concrete is adhering. The machine comprises a roller having longitudinal grooves extending transverse to the form panel, said grooves being pressed into the main surface of the form panel in order to crack the concrete. A rotating brush, also extending transverse to the form panel, will then brush away the loose residual concrete from the main surface. The side edges of the form panel are scraped by scraping irons. The cleaning of the main surfaces of the form panel is sufficient while the cleaning of the edges is unsufficient. This known machine has been tested with shuttering joist of wood but the cleaning is unsufficient because the concrete residuals adhere strongly to the wood. Although the concrete is cracked the brushes do not suffice to clean the main surfaces of the form panels.
The object of the present invention is to provide a machine of the kind referred to above which is simple to operate, easy to move from working site to working site, which will clean form boards and shuttering joist of wood efficiently using a dry method of cleaning. In accordance with the invention this is achieved by grinding preferably milling the form board/shuttering joist using a dry method of cleaning. The wooden material should be damaged only to the extent which is necessary to sufficiently remove concrete residuals.
The machine is adjustable for treating form boards/shuttering joist of different widths. The characterizing features of the invention are set forth in the accompanying claims.
In accordance with a preferred embodiment the cleaning station is pivotally arranged in relation to the roller conveyor, on which the shuttering joists are advanced, in order to closely follow the opposite side surfaces of a shuttering joist should the longitudinal axis thereof rather than being a straight line be a curved lined.
The invention also relates to a system for cleaning form boards or shuttering joist of wood. Shuttering joist with concrete residuals adhering thereto arrive in a disordered state, for example lying on the flat bed of a lorry, to the site of the system. Further to cleaning the shuttering joists the system shall also load test each shuttering joist, print a mark, for example a company's name, on each shuttering joist, stain each shuttering joist and order the shuttering joist so treated into strapped bundles or packages which are easy to handle. The system shall rationalize the handling of the shuttering joists and it shall clean a large number of joists in short time using only two operators maximally, one operator inserting the sputtering joists into the input end of the system and the other taking care of the strapped bundles of joists at the output end of the system, using for example a fork-lift truck.
Load testing of shuttering joists has previously been carried out by manually inspecting each individual joist, a time consuming job which moreover is unreliable since no load testing is carried out during the inspection. In accordance with the present invention each shuttering joist is subjected to load testing.
The invention will be described below with reference to the accompanying drawings wherein

Figure 1 is a perspective view of the machine in accordance with the invention,
Figure 2 is a perspective view of the cleaning station of the machine,
Figure 3 is a side view of bias and stop means,
Figure 4 is a perspective view of a driving station,
Figure 5 is a schematic top view of the machine shown in Figure 1,
Figure 6 is a side view of the machine shown in Figure 5,
Figure 7 is a perspective view of the system in accordance with the invention,
Figure 8 is a perspective view of the machine in accordance with the invention said machine being modified to comprise a load testing station,
Figure 9 is schematic side view of the load testing station,
Figure 10 is a perspective view of a first and a second transfer station and of a lifting table,
Figure 11 is a side view of a movable joist stopping device comprised in the first transfer station shown in Figure 10, and
Figure 12 is a front view of a package of shuttering joists tied up in a bundle.

In Figure 1 there is shown a shuttering joist 1 also referred to as a form beam, with I-shaped cross-section. On the two opposite side surfaces thereof concrete residuals 2 are adhearing to the joist. Said residuals 2 must be removed to permit reuse of the shuttering joist in a new form.
The machine by which the residuals are removed comprises an elongate support structure 3 with legs 4. In the side members 5, 6 of the support structure 3 a series of rollers 7 are rotably mounted so as to form a roller conveyor on which shuttering joists are advanced through a first driving station 8, a cleaning station 9 and a second driving station 10 in the indicated order. In order to operate the machine electric current and pressurized air are required. Electric and pneumatic control equipment for the operation of the machine are mounted within a control cabinet 11. Control signals to the eletric and pneumatic control equipment in the control cabinet are provided from sensors to described further below.
In Figure 2 the cleaning station is shown. This cleaning station comprises two electrical motors 12, 13 on the output shafts of which cylinders 14 and 15 respectively are mounted. The surface of each cylinder is hard and structured and is so designed that upon contact with the side surface of a shuttering joist concrete residuals 2 adhering thereto will be removed by grinding. In the embodiment shown the surface of the cylinder is of hard metal and has been machined so as to form rows of pyramid shaped projections extending around the periphery of the cylinder. The motors will rotate the cylinders at a high rotational speed. The peripheral speed of the cylinders is considerably higher than the speed at which a shuttering joist is advanced on the roller conveyor. Since concrete comprises gravel and sand the cylinder surface will be exposed to great wear. Each electric motor is mounted at one end of a respective arm 16 and 17, the opposite end of each of said arms being pivotally supported on a common vertical pivot pin 18. The pivot pin 18 is stationary mounted on a transverse bar 19 extending between the side members 5 and 6 of the support structure. The unit formed by the arms and motors is suspended in the pivot pin 18 around which the unit may swing in order to follow the side surfaces of the shuttering joist should the latter be askew. A releasable bias means 20 in the form of a pneumatic cylinder extends between the free end of the two arms. When the bias means 20 is in its unreleased state the distance between the two arms and therefore also between the two cylinder surfaces is somewhat larger than the width of a shuttering joist. When the bias means is relased by a limit sensor to be described further below the bias means 20 will force the cylinders 14, 15 towards each other and into contact with the opposite side surfaces of the shuttering joist. In order to prevent that no more wood is removed than what is required to remove the concrete residuals 2, stopping means 21 are provided that restrict the minimum distance between the cylinders and therefore also the maximum wood removal of the cylinders.
As appears from Figure 3 said stopping means comprises a sleeve 22 pivotally mounted at the end of the arm 16 opposite to the pivot pin 18 as well as the threaded rod 23 which also is pivotally mounted at arm 17. The threaded rod 23 has at one end thereof a transverse pin 24 extending between oblong openings 25 provided in the wall of the sleeve 22 at diametrically opposite sites. At the opposite end of the threaded rod there is a mounting member 23A which is threaded on the rod 23 and which is rotably journalled at arm 17. The mounting member 23A is used for setting the minimum distance between the cylinders.
Since both driving stations 8 and 10 are identical only driving station 8 will be described in detail. Driving station 8 is advancing the shuttering joist on the roller conveyor at the input end of the conveyor and driving station 10 is advancing the shuttering joist at the output end of the roller conveyor.
In Figure 4 the driving station 8 is shown in detail. It comprises a stationary lower plate 26 suspended between the side members 5, 6 of the support structure 3. A plate 27 is pivotally mounted on the stationary plate 26 in pivot means 28, 29. At a certain distance above the surface of the pivoted plate a driven roller 30 is mounted. One end of the driven roller is journalled in a mounting bracket 31 and the other end of the roller is journalled in the housing of a gear box 32 the input and output shafts of which are perpendicular. An electric motor 33 is mounted in the gear box 32 in a cantilever manner. The gear box 32 is supported on the pivoted plate 27 by means of a cubical support member 34. When the electric motor 33 is energized by a limit sensor to be desribed further below the output shaft of the motor will, via the reduction gear 32, drive the driven roller 30 at a rotational speed corresponding to the speed at which the shuttering joist is advanced along the roller conveyor when the driven roller is in driving engagement with the upper surface of the shuttering joist. A piston and cylinder unit 35, not shown in Figure 4 for the sake of clearness, but shown in Figure 6, holds the pivoted plate 27 and the unit, formed by members 30-34, sitting thereon in a normal rised position in which the lower surface of the driven roller 30 is sitting 2-3 centimetres above the upper surface of the shuttering joist as is shown in Figure 6. The piston and cylinder unit 35 is of pneumatic type and is attached to the stationary plate 26. A piston 36 extends through an opening in the stationary plate 26 and is at its upper end attached to the pivoted plate 27 as is schematically shown at nut 37 in Figure 4. When the piston and cylinder unit 35 is activated by a limit sensor to be described further below the piston and cylinder unit will swing the pivoted plate 27 in the anti-clockwise direction in Figure 4 from its rised position to a position in which the lower portion of the driven roller 30 engeages the upper surface of the shuttering joist. Simultaneously therewith the electric motor 33 is energized and the shuttering joist will now be advanced on the roller conveyor formed by rollers 7.
In Figure 6 it is shown that the height of the stationary plate 26 may be set in relation to the support structure 3 with the aid of threaded rods 38 provided in the four corners of the lower plate 26 said rods cooperating with locking nuts 39 provided at the side members 5 and 6 respectively of the support structure.
During its advancement on the roller conveyor the shuttering joist is guided by a number of guide members 40 sliding on the lower side of the web of the shuttering joist. Each guide member 40 is mounted on a vertical column 41 which is attached to a transverse bar 42 extending between the side members 5, 6 of the support structure.
A limit sensor 43 provided upstream the cylinders of the cleaning station but downstream the driving station 8 activates the electric motors 12, 13. Another limit sensor 44 located somewhat downstream the driving station 8 activates the piston and cylinder unit 35 as well as the electric motor 33. A similar limit sensor is also provided downstream the driving station 10 in order to active the motor and piston and cylinder unit associated with the driving station 10 although said latter limit sensor is not shown in the drawings. Each limit sensor 43, 44 comprises a switch which is operated by a piece of stiff metal wire 45 and 46 respectively, each said piece of stiff metal wire projecting into the path of a shuttering joist. When the transverse edge of the front surface of a shuttering joist hits the wire the latter is bent and will now operate its associated switch. When the transverse edge of the trailing end surface of the shuttering joist has passed a limit sensor the piece of metal wire 45 and 46 respectively returns to its upright position by spring action. When the piece of stiff metal wire 45 is bent it will operate its associated switch and now the biasing means 20 will open the arms 16, 17 and stop the motors 12, 13. The metal wire 46 operates its associated switch and this will swing the pivoted plate 27 in an upward direction and stop the motor 33. Each switch is connected to the control equipment, the electrical as well as the pneumatical, with electrical conductors. The limit sensor 43 is attached to one of the arms 16 or 17 while the limit sensor 46 is attached to a transverse bar, not shown, extending between the side members 5, 6 of the support structure.
The above described embodiment can be modified and varied in many ways. The surfaces of the cylinders 14, 15 may for example have different configurations than the one described. As an alternative each surface may be smooth and have a grinding band fitted thereon. The grinding band comprises particles of carborundum adhering to a base of paper, paper coated web of plastic, fibres or any other base material. Instead of cleaning the side surfaces of a shuttering joist having an I-shaped cross-setion common boards can be cleaned. In the latter case the guide members 40 are replaced with guiding means between which the longitudinal side surfaces of the boards are guided. The stopping means 21 can have other designs than that shown. Beams and boards of different widths can be cleaned by resetting/changing the guiding members and by resetting the stopping means. The various piston and cylinder units may be of hydraulic type or may be electrically driven.
In Figure 7 the system in accordance with the invention is shown in a perspective view as seen from above. At the input end of the system there is a shuttering joist support plate 50 on which a shuttering joist is manually placed and is aligned with the roller conveyor of the machine in accordance with the invention. First the shuttering joist will pass a printing station 51 before it enters a modified machine in accordance with the invention. The machine is housed in a protective casing 52 within which a load testing station and the previously described cleaning station are housed. After leaving the cleaning station the shuttering joist enters a staining station which also is covered by a protective casing 53. From the staining station the shuttering joist enters a shuttering joist collecting unit, comprising a frame 54 supporting a first transfer station 55 at which the shuttering joists are transferred from the roller conveyor to a collecting table 56 on which a predetermined number of joists are collected side by side to form an ordered group of joists. A second transfer station 57 transfers the group of ordered shuttering joists from the collecting table 56 to a lifting table 58. Each transfer of a group of joists is followed by a lowering of the lifting table for a predetermined distance thus preparing the lifting table to receive the next group of joists on the top of the previous group. When the lifting table 58 has been filled with a predetermined number of group of joists the stack of shuttering joist groups is tied with straps and is then ready for removal, for example with the aid of a fork-lift truck.
The shuttering joist support plate 50 comprises a horizontal turning plate 60 supported at the end surface of a vertically extending piston and cylinder unit 61 by which the height of the turning plate is set. The shuttering joist support plate is aligned with the longitudinal axis of the roller conveyor. The operator of the machine puts the forward end portion of a joist on the support plate 50 and then he lifts the rear end of the joist, turns the joist on the support plate until the joist is aligned with the roller conveyor. Finally he pushes the joist onto the roller coveyor.
In this modified embodiment of the machine the roller conveyer is driven. Said printing station 51 is also provided at the input end of the system. The printing station comprises a printing roller 62 around the periphery of which there is embossed a company's name for example. A paint transfer roll, not shown in the drawing, is inking the printer roller. Under control from the control equipment in the control cabinet the printing roller is pressed into engagement with the web portion of a shuttering joist passing the station. In a preferred embodiment of the invention the printing roller is brought into contact with the shuttering joist for a time that corresponds to the time it takes the printing roller to do one revolution.
In the modified embodiment of the invention the roller conveyor has a slot 63, defined by rollers 7-1 and 7-2, as seen in Figure 8. The driving station 8 is situated approximately midway between the rollers 7-1, 7-2. When the forward end of the shuttering joist hits the limit sensor 44 the pneumatical piston and cylinder unit 35 will press the driving station 8 in a downward direction with a predetermined force. The driven roller 30 will thus subject the joist section between rollers 7-1 and 7-2 for a predetermined load and at the same time the driven roller 30 starts to rotate thus advancing the shuttering joist along the roller conveyor. In this way the shuttering joist will be subjected to a progressive load testing when passing the load testing station.
A number of spray nozzles are arranged within the protective casing 53 in order to spray stain on all surfaces of the shuttering joist. The stain is applicated in a thin layer which is soaked by the wood. Almost no stain will take on the downstream machinery.
As appears from Figure 10 the roller conveyor extends all the way under the frame 54. At the end of the roller conveyor there is an optic limit sensor 65.
The frame 54 has two upper beams 66, 67 extending transversly to the roller conveyor. At the underside of each beam a rodless piston and cylinder unit 68 and 69 respectively is mounted. Rodless piston cylinder units are known and are used to generate linear motion. They are either pneumatic or electric. A joist pusher 70 secured in each piston 68, 69 extends parallel to the roller conveyor. The joist pusher 70 comprises a beam having a number of joist pusher plates 71 hinged thereto, said plates depending from the beam and being adapted to engage the right side surface of a shuttering joist using the directions of Figure 10. The joist pusher 70 is movable between a start position in which it is situated to the right of the right side surface of a shuttering joist advanced on the roller conveyor and an end or delivery position in which the joist pusher is situated some distance above the collecting table 56, inward thereof, approximately at the site of arrow 72 where the joist pusher delivers the joist. The pusher plates 71 are hinged to the beam to cope the situation which arises when a new joist is advancing on the roller conveyor while simultaneously the joist pusher is returning from the delivery position to the start position. When this situation occurs the pusher plates will swing in the clockwise direction when hitting the left side surface of the advancing joist.
A stationary joist stopping device 73 is arranged at the left part of the collecting table 56, said joist stopping device being mounted in the frame and comprising a long rod or beam. A movable joist stopping device 74 comprises a pivoted rod or beam extending along the table and being attached to a number of vertically projecting columns 75 provided along the pivoted rod. In Figure 11 the construction is shown in detail. Each column 75 is provided with a pivot pin 76 around which a pivot plate 77 is mounted. The movable joist stopping device is welded to the pivot plates 77 in the manner shown in Figure 11. At the opposite end of the pivot plate one end of a piston and cylinder unit 78 is mounted. The opposite end of said piston and cylinder unit is supported at the end of a rod 79, said rod being welded either to the frame or to the stationary joist stopping device. In this way the movable joist stopping device may swing between an inactive raised position above the table as shown with solid lines in Figure 11 and an active low position shown with broken lines in figure 11.
The first transfer station 55 is controlled by control equipment in the control cabinet 11 and is operated in the following manner: When the forward end of a joist advancing on the roller conveyor is detected by the optic limit sensor 65 the cylinders 68, 69 are simultaneously operated and will move the joist pusher 70 from its start position to its delivery position. During this movement the joist pusher is pushing the joist. The joist is delivered at a position inward the table and finally the joist pusher returns to its start position, waits for a new signal from the optic beam sensor 65, is again activated and starts to transfer the next joist, said next joist then pushing the previous joist to the left. This cycle is repeated until a predetermined number of joists has been counted by the control equipment. In the preferred embodiment the first transfer station operates in the following manner: When the movable joist stopping device is in its inactive raised position the left side of the leftmost joist on the collecting table will contact the stationary joist stopping device 63 as the joist pusher 70 delivers the fifth joist. If the movable joist stopping device is in its active low position shown with broken lines in Figure 11 the left side of the leftmost joist on the collecting table will contact the movable joist stopping device 74 when the joist pusher 70 delivers the fourth joist. It is also appreciated that the position of this leftmost joist is displaced in relation to the position of the leftmost joist of the previous group of five joists.
The second transfer station 57 comprises two beams 81, 82 welded to the frame 44 parallel to each other and to the roller conveyor. At the underside of each beam 81, 82 a rodless, linear motion generating piston and cylinder unit 83 and 84 respectively is mounted. A movable joist group pusher 85 comprising a frame structure, a pusher beam and a pair of wheels 86, is attached to the piston of each piston and cylinder unit 83, 84 and is movable between a start position, in which the joist group pusher is at a distance behind, using the directions of Figure 10, the table and a delivery position somewhat ahead of the front surfaces of the joists of a group of joists laying on the table. The movable joist group pusher 85 is activated by control equipment within the control cabinet 11. In the preferred embodiment the joist group pusher 85 is activated when five joists are laying on the collecting table, the movable joist stopping device 74 is in its inactive raised position and the leftmost joist a group of joists is in contact with the stationary joist stopping device 73 and also in the case when four joists are laying on the collecting table and the movable joist stopping device 74 is in its active low position. When the joist group pusher 85 has pushed a group of joists over to the lifting table 54 the lifting table is lowered by an amount allowing the following group of joists to be placed over the previous.
The control equipment will allow fifty joists, arranged in the manner shown in Figure 12, to lay on the lifting table 58 in a position ready to be tied up in a bundle. By arranging one group of joists displaced in relation to the next, the volume of the joist bundle is reduced. It is apparent that the piston and cylinder units 78 of the movable joist stopping device 74 are controlled by the control equipment in the control cabinet 11 in such a manner that each second group of joists on the table is displaced in relation to the previous one.
If the invention is used in conjunction with boards of wood having a different cross-section, for example a square or rectangular cross-section, then the movable joist stopping device 74 may be omitted. The movable joist group pusher can be activated when other numbers of joists than those referred to above are laying on the collecting table.

Claims

1. Machine for cleaning wooden shuttering joists, in particular for removing concrete residuals adhering thereto, comprising
- an elongate frame (3),
- a series of rollers (7) journalled in the frame for supporting a shuttering joist (1) on the roller conveyor formed by said rollers,
- guide means (40) for guiding the shuttering joist along the roller conveyor,
- at least one driving station (8, 10) for advancing a shuttering joist along the roller conveyor and
- a cleaning station (9) provided at the frame and adapted to engage two opposite surfaces of the shuttering joist in order to clean said surfaces,
characterized in that
- said cleaning station comprises two opposite, separately driven cylinders (14, 15) each having a hard, structured surface for removal of concrete residuals (2) from the side surfaces of a shuttering joist by grinding, preferably milling.

2. Machine in accordance with claim 1, characterized in that the surface of the cylinders is of hard metal and that the structured surface is formed by pyramid shaped projections of hard metal.

3. Machine in accordance with claim 1, characterized in that
- each cylinder (14, 15) is provided on the output shaft of a respective electric motor (12, 13),
- that each electric motor (12, 13) is provided on one end of a respective arm (16, 17),
- that the opposite end of each arm (16, 17) is journalled on a vertical pivot pin (18) common to the arms and provided on a transverse bar midway between the longitudinal side members (5, 6) of the frame,
- that biasing means (20) are provided between said arms to bias the arms and therefore also the cylinders (14, 15) towards each other.

4. Machine in accordance with claim 3, characterized by stopping means (22, 23) for restricting the swingning movement of said arms (16, 17) and therefore also of said cylinders (14, 15) towards each other around said pivot pin (18).

5. Machine in accordance with claim 4, characterized in that said baising means comprises a releasable pneumatic cylinder (20) extending between said two arms (16, 17) at the ends thereof which are opposite to the pivot pin (18), said cylinder (20) in its unreleased state holding out said arms from each other thus preventing the cylinders from contacting the longitudinal side surfaces of a shuttering joist (2).

6. Machine in accordance with claim 4, characterized in that said stopping means comprise a sleeve (22) pivotally connected to one (16) of said arms at the end opposite said pivot pin, and a threaded rod (23) pivotally connected to the other (17) arm at the end opposite said pivot pin, said threaded rod (23) at its free end comprising a transverse pin (24) extending through elongate openings (25) provided in the wall of said sleeve (22) at diametrically opposed positions.

7. Machine in accordance with claim 1, characterized in that each driving station (8, 10) comprises:
- a stationary lower plate (26) provided at said frame (3),
- a pivoted plate (27) pivotally connected to the stationary lower plate at pivot means (28, 29),
- a driven roller (30),
- journal and mounting means (31, 34) for attaching the driven roller (30) to the pivoted plate at a distance above its upper surface, the longitudinal axis of said driven roller extending generally perpendicular to the longitudinal axis of said shuttering joist while simultaneously the surface of said driven roller is generally parallel to the upper surface of the shuttering joist,
- an electric motor (33) provided at said mounting means (34), to drive said driven roller,
- a pneumatic piston and cylinder unit (35) provided at the underside of the stationary plate and actuating said pivoted plate (27) so as to, when actuated, swing said plate (27) in a downward direction until the driven roller (30) contacts the upper side of the shuttering joist thereby transferring its rotational movement to a translatory movement of the shuttering joist on the roller conveyor.

8. Machine in accordance with claim 7, characterized in that a limit sensor (44) is provided in the roller conveyor downstream the driving station (8, 10), said limit sensor being adapted to activate said pneumatic piston and cylinder unit (35) as well as the electric motor (33) of the driven roller when it is hit by the forward edge of a shuttering joist.

9. Machine in accordance with claim 5, characterized by an additional limit sensor (43) provided in the roller conveyor upstream said cleaning station (9), said additional limit sensor being adapted to activate the releasable means (20) as well as the electrical motors (12, 13) of said cylinders when it is hit by the forward edge of a shuttering joist.

10. Machine in accordance with any of the preceding claims, wherein said shuttering joist has an I-shaped cross-section, characterized in that said guiding means comprises a guide member (40) provided in the roller conveyor, said member fitting in the web portion of the I-shaped cross-section of the shuttering joist.

11. Machine in accordance with any of the preceding claims, characterized by a load testing station for load testing of the shuttering joists.

12. Machine in accordance with claim 11, characterized in that the load testing station comprises two adjacent rollers (7-1, 7-2) in said roller conveyor, said adjacent rollers being spaced apart by a predetermined distance so as to form a slot (63) in the roller conveyor, said distance being shorter than the full length of a shuttering joist, a driven roller (30) of a predetermined driving station (8), said driven roller being arranged above the shuttering joist and generally midway in the slot, and the pneumatic piston and cylinder unit (35) associated with said predetermined driving station (8), said pneumatic piston and cylinder unit being adapted to press, with a predetermined force, the driven roller (30) into contact with the upper side of a shuttering joist so as to deflect said joist between said two adjacent rollers (7-1, 7-2) at the same time as the driven roller rotates and advances the deflected joist along the roller conveyor.

13. Machine in accordance with any of the previous claims, characterized by a printing station (51) for printing a mark, for example a company's name, on the joists, said printing station being arranged at said roller conveyor.

14. Machine in accordance with any of the previous claims, characterized by a spraying station (53) provided in the roller conveyor between the cleaning station and the exit portion of the roller conveyor so as to spray liquid stain on the shuttering joists.

15. Machine in accordance with any of the previous claims, characterized in that a horizontal turnable shuttering joist support plate (50) is provided at the entrance of the roller conveyor.

16. Machine in accordance with any of the previous claims, characterized by a first transfer station (55) for transferring shuttering joists, one at a time, from the roller conveyor (7) to a collecting table (56) on which the shuttering joists are placed beside each other so as to form a group, a second transfer station (57) for transferring successive groups of shuttering joists to a lifting table (58) in such manner that one layer of shuttering joists is placed over the preceding layer.

17. Machine in accordance with claim 16, characterized in that said first transfer station comprises a frame (54), a collecting table (56) provided in said frame beside the roller conveyor (7), two rodless piston and cylinder units (68, 69) generating linear movement, mounted in said frame, extending parallel to each other and extending perpendicular to the roller conveyor, a joist pusher (70) extending perpendicular to said cylinders and adapted to be moved from a start position, in which the roller conveyor is between said joist pusher and the table, and a delivery position, in which the joist pusher is situated a distance inward the board so as to deliver the shuttering joist just removed from the roller conveyor, and a stationary joist stopping device (73) provided along the side of the table opposite the roller conveyor (7) and defining a first position of a group of joists collected on the table.

18. Machine in accordance with claim 16, characterized in that said second transfer station (57) comprises two rodless piston and cylinder units (83, 84) generating linear movement, attached to the frame in parallel, positioned above the table and extending parallel to the roller conveyor, a movable joist group pusher (85) extending perpendicular to the piston and cylinder units (83, 84) and adapted to be pushed thereby from a start position, in which the joist group pusher is located at a distance behind the rear end surface of a group of joists collected on the table, and a delivery position in which the joist group pusher (85) is situated a distance ahead of the forward end surface of said group of joists so as to transfer the group of joists from the collecting table (56) to a lifting table (58).

19. Machine in accordance with claim 18, characterized in that the joist group pusher comprises a transverse beam adapted to be brought into contact with the end surfaces of the shuttering joists and a pair of wheels (86) attached to said transverse beam and adapted to roll on the table so as to stabilize the linear motion of the joist group pusher when it is pushing the joists.

20. Machine in accordance with any of the previous claims, wherein the shuttering joist has an I-shaped cross-section, characterized in that a movable joist stopping device (74) is provided along the side of the collecting table (56) opposite the roller conveyor (7), said movable joists stopping device being pivoted between a raised inactive position above the table and a lower active position defining a second position of a group of joists collected on the table, said second position being displaced relative to the first position with an amount corresponding to half the width of a shuttering joist.

21. Machine in accordance with claim 20, characterized in that the movable joist stopping device (74) comprises a beam, a number of pivot plates (77) distributed along the beam, vertically extending columns (75) loacted near the pivot plates, attached to the frame and provided with pivot pins (76) on which the pivot plates are pivoting, and a piston and cylinder unit (78) provided at each pivot plate, each such unit having one end thereof connected to the pivot plate and its opposite end to the frame so as to swing the pivot plate and therefore also said beam round the pivot pins between the inactive raised position and the active low position.

22. A system for cleaning wood shuttering joists of concrete residuals, characterized by a path including a supply of shuttering joists to be cleaned, a machine in accordance with claim 1 modified to comprise a load testing station for load testing the shuttering joists advancing on the roller conveyor (7), a first transfer station (55) for transferring joists, one at the time, from the roller conveyor to a collecting table (56) on which the shuttering joists are placed beside each other, a second transfer station (57) for transfering successive groups of a collected shuttering joists from the collecting table to a lifting table (58) in such a manner that a layer of joists will be placed over the previous layer, and a bundling station for tying a predetermined number of groups of shuttering joists on the lifting table with straps so as to form a package of treated shuttering joists.

23. A system in accordance with claim 22, characterized in that the shuttering joists are placed beside each other on the collecting table (56) in either of two alternating types of groups, viz. a first group comprising a first number of joists (five pieces) and taking a first position on the collecting table, and a second type comprising a second number (four pieces) of joists and taking a second position on the collecting table (56), said second position being displaced relative to the first position with an amount corresponding to half the width of a shuttering joist, thereby displacing successive layers of shuttering joists on the lifting table relative to each other (Figure 12).

24. System in accordance with claim 22 or 23, characterized by a printing station (51) provided between said supply and said load testing station to print a mark on the shuttering joists and/or a spraying station provided in the roller conveyor between the cleaning station and the first transfer station (55) and/or a horizontal, turnable shuttering joist support plate (50) provided between said supply and the roller conveyor in alignment with the latter so as to act as a support for a shuttering joist to be placed on the roller conveyor.