HIGHLY VERSATILE NAILING UNIT FOR NAILING MACHINES, PARTICULARLY FOR NAILING WOOD ELEMENTS ON MULTIPLE LAYERS

Abstract

 A nailing unit (1, 1') for nailing machines, particularly for nailing wood elements on multiple layers, comprising a clamp (40) adapted to keep in the nailing position a nail (C) above an element to be nailed, and a plunger (30) adapted to push the nail (C) in order to make it penetrate into the element to be nailed; an actuator (20, 120) which comprises a pusher element (21, 121) which moves along a vertical direction, the pusher element (21, 121) being integral with the plunger (30) and with a vertical traction rod (51) which is provided with a lower locking element (55), along which traction rod (51) the clamp (40) can slide freely to a lower stroke limit position in which it is prevented from moving further downward by the locking element (55), so that when the clamp (40) is in the lower stroke limit position an upward movement of the traction rod (51) draws upward the clamp (40); the clamp (40) comprises a through vertical tunnel (48) in which the plunger (30) can slide until it reaches the nail (C) when it is held in the nailing position by the clamp (40) and then push it.

Description

[0001] The present invention relates to a nailing unit for nailing machines, particularly for nailing wood elements on multiple layers, useful in practice particularly for performing the nailing of wood beams formed by two or more layers.

[0002] In the background art, machines for nailing wood beams on multiple layers comprise, in addition to a lower fixture for managing the movement and retention in position of the wood beams, an upper nailing unit, which is the subject matter of the present invention.

[0003] These nailing units of the known type in turn are composed of two parts, which must be able to move with respect to each other:

• the first one, known as clamp, has the task of containing the nail, which falls by gravity from the upper region of the machine, and of moving into contact with the upper wood piece that must be nailed to the lower one; said clamp therefore has the function of the fingers that hold the nail in manual nailing;
• the second one, known as plunger or needle, has the function of causing the nail to penetrate in the wood pieces and also of providing the force necessary to bend the tip of the nail so that it does not protrude from the lower wood piece (riveting); said plunger therefore has the function of the hammer in manual nailing.

[0004] In nailing units of the known type, the movements of the clamp and of the plunger, which must be mutually synchronized, are produced by two different rod-and-crank systems which are moved by the same crankshaft. Since nailing is performed in the dead center of the crank system, it is easily possible to apply the force required for the operation.

[0005] In order to have a constant movement of the clamp and of the plunger, the resting surface of the clamp, which corresponds to the upper face of the upper wood piece to be nailed, must be fixed. This means that as the thickness of the elements to be nailed (i.e., of the wood pieces that compose the beam) varies, so must the position of the resting surface of the element to be nailed (where the lower wood piece of the beam rests) that is the loading surface on which the operator, or the automatic feeding mechanism, deposits the elements to be nailed. Nailing machines therefore have systems for adjusting the height of the entire loading and unloading region of the machine in order to adapt to the variability of the thickness of the woods pieces to be nailed.

[0006] Therefore, although they are useful and practical, nailing units of the known type have the disadvantage that they can be used only in nailing machines provided with systems for adjusting the height of the loading region (in particular of the resting surface), which disadvantageously increase the space occupation, complexity and costs of the machine.

[0007] The aim of the present invention is to overcome the limitations of the background art described above by providing a nailing unit for nailing machines that can be used in machines not provided with a system for adjusting the height of the resting surface, i.e., with a fixed resting surface.

[0008] Within this aim, an object of the present invention is to provide a nailing unit for nailing machines that is more versatile than the background art.

[0009] Another object of the invention is to provide a nailing unit for nailing machines that is precise and reliable.

[0010] A further object of the invention is to provide a nailing unit for nailing machines that is easy to provide and economically competitive.

[0011] This aim and these objects and others which will become better apparent hereinafter are achieved by a nailing unit according to claim 1.

[0012] Further characteristics and advantages of the invention will become better apparent from the description of two preferred but not exclusive embodiments of the nailing unit according to the present invention, illustrated by way of non-limiting example with the aid of the accompanying drawings, wherein:

Figure 1 is a perspective view of a first possible embodiment of the nailing unit according to the invention in the inactive position;

Figure 2 corresponds to Figure 1, in which some elements have been removed and a detail is shown in cross-section in order to show more clearly the internal structure;

Figure 3 is a perspective view of the nailing unit of Figure 1, with some elements removed, in the nailing position at the beginning of the nailing step;

Figure 4 is a perspective view of the nailing unit of Figure 1, with some elements removed, in the nailing position at the end of the nailing step;

Figure 5 is a perspective view of a second possible embodiment of the nailing unit according to the invention in the inactive position;

Figure 6 corresponds to Figure 5, in which some elements have been removed and a detail is shown in cross-section in order to show more clearly the internal structure;

Figure 7 is a perspective view of the nailing unit of Figure 5, with some elements removed, in the nailing position at the beginning of the nailing step;

Figure 8 is a perspective view of the nailing unit of Figure 1, with some elements removed, in the nailing position at the end of the nailing step.

[0013] With reference to the figures, the nailing unit, designated generally by the reference numeral 1 or 1' depending on the embodiment, is adapted to be installed and used in nailing machines, particularly for nailing wood elements on multiple layers (such as for example beams composed of two or more layers of wood which must be nailed to each other), above a resting surface for the elements to be nailed.

[0014] Normally, in the configuration for use, the resting surface of the nailing machine is substantially horizontal and the nailing unit is positioned so that its working axis is perpendicular to the resting surface.

[0015] In the present description and in the accompanying claims, the term "vertical" is understood to indicate vertical when the nailing unit 1, 1' is in the active position for use, i.e., substantially perpendicular to the resting surface when the nailing unit is installed in the active configuration in a machine, or in any case substantially perpendicular to the resting surface of the machine when installed therein.

[0016] In its essential features, which are common to all the embodiments, the nailing unit 1, 1' comprises a clamp 40, or clamp assembly, which is adapted to keep a nail C in the nailing position above an element to be nailed and a plunger 30 adapted to push the nail C in order to make it penetrate into the element to be nailed.

[0017] The clamp 40 comprises at least one system 49 for receiving the nail C, which, in a known manner, is configured to accommodate the nail C so as to release it, when pushed by the plunger 30, allowing its sliding and its exit from the clamp downward.

[0018] According to the invention, the nailing unit 1, 1' comprises an actuator 20, 120, and more precisely a linear actuator (in the sense that it is of the type that induces a movement along a straight line), which comprises a pusher element 21, 121 (such as a stem or shaft or piston or the like) which moves along a vertical rectilinear direction.

[0019] In some embodiments, such as the one of Figures 5-8, the actuator is an electric linear actuator 120, in which the pusher element 121 is a shaft or stem which is actuated electrically to move along the axis of the actuator 120; in other embodiments, such as the one of Figures 1-4, the actuator is a hydraulic actuator 20 (such as a hydraulic cylinder), in which the pusher element 21 is a stem or piston which is actuated hydraulically to move along the axis of the actuator.

[0020] The pusher element 21, 121 is integral with the plunger 30 and also with a traction rod 51, which also is vertical and is provided with a lower locking element 55.

[0021] In greater detail, the plunger 30 is fixed mechanically to one end of the pusher element 21, 121 so that said element, by moving, pushes or pulls the plunger 30 along said vertical rectilinear direction.

[0022] Preferably, the pusher element 21, 121 is provided, at a distal end (the end that is closest to the clamp 40), with at least one mechanical fixing element 22, 122, which comprises for example one or more jaws or other devices adapted to engage, or in any case fix, mechanically the plunger 30 and the traction rod to the pusher element 21, 121. The plunger 30 and the traction rod 51 can in any case be fixed to the pusher element 21, 121 by means of any known fixing method.

[0023] The clamp 40 can slide freely along the traction rod 51 to a lower stroke limit position in which it is prevented from moving further downward by the locking element 55 (as can be seen in Figures 1 and 5), the clamp 40 being in practice suspended from the traction rod 51 when the rod is raised.

[0024] In the examples shown, the locking element 55 is a (preferably annular) shoulder that is present on the traction rod 51 and is formed for example by a ring which is keyed on the rod 51, said annular shoulder 55 being configured to block the downward movement of an abutment surface which is integral with the clamp 40.

[0025] The abutment surface is for example a lower surface of a ring 45, or other sliding element, which can slide along the sliding rod 51, such ring 45 or other sliding element being rigidly coupled to the clamp 40 (for example being fixed to the plate 44, which will be described hereinafter, which in turn is fixed to the clamp 40); in this case, therefore, the shoulder or other locking element 55 blocks the downward sliding of the ring 45 or other sliding element which is integral with the clamp 40.

[0026] In this manner, when the clamp 40 is in the lower stroke limit position, an upward movement of the traction rod 51 pulls the clamp 40 upward with it.

[0027] Therefore, during operation, when an element to be nailed is positioned below the nailing unit 1, 1', when the traction rod 51 moves downward the clamp 40 moves downward by gravity until it rests on the element to be nailed.

[0028] According to the invention, the clamp 40 comprises a through vertical tunnel 48 (i.e., any opening or passage) in which the plunger 30 can slide until it reaches the nail C when it is held in the nailing position by the clamp 40 and therefore push it by virtue of the action of the force imparted by the linear actuator 20, 120 (by means of the pusher element 21, 121) to the plunger 30, making the nail C exit downward from the seat of the clamp 40.

[0029] As is evident from the figures, the nailing unit 1, 1' can be configured in an inactive condition (which is the one in which it is before performing nailing), visible in Figures 1 and 5, in which the clamp 40 is raised with respect to the nailing position and in which the plunger 30 is higher than the clamp 40.

[0030] In the preferred embodiments, the clamp 40 and the plunger 30 are both slidingly coupled (directly or preferably indirectly) to a same vertical sliding guide 60 which constrains their movements parallel to it; this solution ensures optimum alignment of the two elements (the clamp 40 and the plunger 30) and is advantageous from the point of view of space occupation.

[0031] In greater detail, the clamp 40 is coupled to the sliding guide 60 at least by means of a slider 43, which can slide along said sliding guide 60, and preferably the clamp 40 is connected to the slider 60 by means of a plate 44 which is integral both with the clamp 40 and with the slider 43.

[0032] The plunger 30 also is coupled indirectly to the sliding guide 60 at least by means of a slider of the pusher element 33, which can slide along the sliding guide 60 and is rigidly coupled to the pusher element 21, 121, preferably by means of at least one interposed plate 34. In practice, the plunger 30 is rigidly coupled to the pusher element 21, 121, which, by means of the plate 34, is coupled to the slider of the pusher element 33.

[0033] Conveniently, the nailing unit 1, 1' comprises a supporting structure 80, 180, which supports directly or indirectly all the elements described so far.

[0034] Preferably, the supporting structure 180 comprises protective side walls which are positioned so as to protect at least partially at least the actuator 20, 120.

[0035] Preferably, the supporting structure 180 comprises a rear wall 81, 181 which is optionally configured to fix the nailing unit 1, 1' to the structure of a nailing machine.

[0036] In the preferred embodiments, the sliding guide 60 is fixed to an internal face of said rear wall 81, 181.

[0037] Optionally, the nailing unit 1, 1' is provided with, or can be functionally connected to, a programmable electronic control unit, for example of the type of a programmable logic controller (PLC), which controls the operation of the actuator 20, 120 by sending a nailing signal as a consequence of which the actuator 20, 120 moves downward the pusher element 21, 121, inducing the downward movement of the clamp 40 and of the plunger 30; the clamp 40 stops when it encounters the surface of the element to be nailed and the plunger 30 continues the movement, as described above, pushing the nail C and performing the nailing.

[0038] The same electronic control unit induces the actuator 20, 120 to reverse the motion of the pusher element 21, 121 when the nail C has completely penetrated into the element to be nailed, thus lifting initially the plunger 30 and then also the clamp 40.

[0039] The operation of the nailing unit according to the invention can therefore be summarized with the following steps:

a) from the inactive condition (which is visible in Figures 1 and 5), with the clamp 40 and the plunger 30 higher than the maximum height of the thickness of the element to be nailed (of the wood pieces), upon reception of the nailing signal the actuator 20, 120 moves toward the element to be nailed simultaneously the clamp 40 and the plunger 30;

b) when the clamp 40 encounters the element to be nailed (the surface of the wood piece), it stops, but the pusher element 21, 121 of the actuator 20, 120 continues to move, pushing the plunger 30 inside the clamp 40 and therefore pushing the nail C into the element to be nailed (into the wood piece), as can be seen in the transition from Figure 3 to Figure 4 and from Figure 7 to Figure 8;

c) when the nail C has completely penetrated into the element to be nailed (in the wood piece) and the head of the nail C has moved, by a preset number of desired millimeters, past the upper surface of the element to be nailed, the actuator 20, 120 reverses its motion;

d) for a first rising portion, there is only the movement of the plunger 30;

e) when the locking element 55 of the traction rod 51 reaches the abutment surface that is integral with the clamp 40, the clamp 40 also is entrained in motion and rises together with the plunger 30 up to the inactive position.

[0040] Essentially, therefore, the resting surface of the nailing machine in which the nailing unit 1, 1' according to the invention is used can be kept fixed, since the movements of the clamp 40 and of the nail C and of the plunger 30 adapt to the thickness of the elements to be nailed.

[0041] With reference now in greater detail to the embodiment of Figures 1-4, therein the linear actuator is a hydraulic actuator 20 which comprises a hydraulic cylinder and a stem which constitutes the pusher element 21 and is pushed by the action of a fluid (preferably oil) that is present in the hydraulic cylinder.

[0042] Preferably, in this embodiment the nailing unit 1 comprises a system for control and adjustment of the temperature of the fluid of the hydraulic actuator 20 which is configured to maintain the temperature of said fluid within a preset interval; this temperature control and adjustment system comprises at least one temperature sensor. The provision of a system or apparatus for the control and adjustment of the temperature of a fluid is within the grasp of the person skilled in the art and therefore is not dwelt upon further.

[0043] Also in this embodiment, the nailing unit 1 preferably also comprises a position sensor (which comprises for example a proximity sensor), which is configured to detect the position of the nail C with respect to the element to be nailed or, even more preferably, to detect the position of the plunger 30 with respect to the clamp 40; in this case, the programmable electronic control unit controls the linear actuator 20 as a function of the position detected by the position sensor, i.e., it induces the reversal of the motion of the pusher element 21 when a preset position of the plunger 30 with respect to the clamp 40 (or of the nail C with respect to the element to be nailed) that is indicative of the complete penetration of the nail C is detected.

[0044] In this embodiment it is preferable to perform a preliminary calibration step in order to identify the optimum position to be detected in order to send the motion reversal signal, for the specific type of element to be nailed, optionally setting in the electronic control unit a delay time and/or varying the position of the sensor.

[0045] With reference now in greater detail to the embodiment of Figures 5-8, therein the linear actuator is an electric linear actuator 120.

[0046] Preferably, the electric linear actuator comprises a linear axis actuator 120 (i.e., an actuator of the type known as linear electric shaft) which is driven by a brushless electric motor 129, which is functionally connected to the electronic control unit that controls its movement; in this embodiment, the pusher element 121 is the linearly sliding shaft of the linear electric shaft 120.

[0047] In this solution, therefore, the electronic control unit that control the movement of the nailing unit 1, 1' known in every instant the position of the plunger 30 by means of the electric motor.

[0048] The electric linear actuator 120 is appropriately sized so as to ensure the force necessary for nailing, but it can also be provided with a torque control system which allows to limit the force if a force that exceeds the expected one is required (for example due to improper use of the machine).

[0049] The electric linear actuator 120 thus provided allows to control speed and acceleration both during descent and during ascent.

[0050] The electric linear actuator 120 thus provided allows to stop the plunger 30 exactly at the desired height, regardless of the diameter of the nail C, of the penetration length, and of the hardness of the wood.

[0051] By virtue of the electric linear actuator 120 thus provided it is possible to synchronize perfectly the penetration movement of the nail C with the movement of a so-called riveter (a plate which is arranged below the elements to be nailed, is provided with a horizontal movement and is also actuated electrically).

[0052] Embodiments are not excluded in which the actuator 20, 120 is an electrical linear actuator 120 and in which there is in any case also the position sensor.

[0053] In practice it has been found that the nailing unit according to the present invention achieves the intended aim and objects, since it can be used in machines not provided with a system for adjusting the height of the resting surface, i.e., with a fixed resting surface.

[0054] Another advantage of the nailing unit according to the invention resides in that it is more versatile than the background art.

[0055] A further advantage of the nailing unit according to the invention resides in that it is precise and reliable.

[0056] Another advantage of the nailing unit according to the invention resides in that it is easy to provide and economically competitive.

[0057] The nailing unit thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the accompanying claims.

[0058] All the details may furthermore be replaced with other technically equivalent elements.

[0059] In practice, the materials used, as well as the contingent dimensions and shapes, may be any according to the requirements and the state of the art.

[0060] The disclosures in Italian Patent Application No. 102021000026903 from which this application claims priority are incorporated herein by reference.

[0061] Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

1. A nailing unit (1, 1') for nailing machines, particularly for nailing wood elements on multiple layers, comprising a clamp (40) adapted to keep in the nailing position a nail (C) above an element to be nailed, and a plunger (30) adapted to push the nail (C) in order to make it penetrate into the element to be nailed,

characterized in that it comprises an actuator (20, 120) which comprises a pusher element (21, 121) which moves along a vertical direction, said pusher element (21, 121) being integral with the plunger (30) and with a vertical traction rod (51) which is provided with a lower locking element (55), along which traction rod (51) the clamp (40) can slide freely to a lower stroke limit position in which it is prevented from moving further downward by said locking element (55), so that when the clamp (40) is in said lower stroke limit position an upward movement of said traction rod (51) draws upward said clamp (40);

said clamp (40) comprising a through vertical tunnel (48) in which said plunger (30) can slide until it reaches the nail (C) when it is held in the nailing position by the clamp (40) and then push it.

2. The nailing unit (1, 1') according to claim 1, characterized in that it can be configured in an inactive position in which the clamp (40) is raised with respect to the nailing position and in which the plunger (30) is higher than the clamp (40).

3. The nailing unit (1, 1') according to claim 1 or 2, characterized in that the clamp (40) and the plunger (30) are both coupled slidingly to a same vertical sliding guide (60).

4. The nailing unit (1, 1') according to claim 3, characterized in that the clamp (40) is coupled to said sliding guide (60) at least by means of a slider (43) which can slide along said sliding guide (60).

5. The nailing unit (1, 1') according to claim 4, characterized in that the clamp (40) is connected to the slider (43) by means of a plate (44) which is integral both with the clamp (40) and with the slider (43).

6. The nailing unit (1, 1') according to one or more of claims 3 to 5, characterized in that the plunger (30) is coupled to said sliding guide (60) at least by means of a slider of the pusher element (33) which can slide along said sliding guide (60) and is coupled rigidly to the pusher element (21, 121).

7. The nailing unit (1') according to one or more of the preceding claims, characterized in that said actuator (20, 120) is an electric linear actuator (120).

8. The nailing unit (1') according to claim 7, characterized in that said electric linear actuator (120) comprises a linear electric shaft which is controlled by a brushless electric motor (129) functionally connected to a programmable electronic control unit which controls its movement.

9. The nailing unit (1') according to one or more of the preceding claims 1 to 6, characterized in that said linear actuator (20, 120) is a hydraulic actuator (20) which comprises a hydraulic cylinder and a stem which is pushed by the action of a fluid that is present in said hydraulic cylinder, said pusher element (21) comprising said stem.

10. The nailing unit (1') according to claim 9, characterized in that it comprises a system for the control and adjustment of the temperature of the fluid of the hydraulic actuator (20) which comprises at least one temperature sensor, configured to maintain the temperature of said fluid within a predetermined interval.

11. The nailing unit (1, 1') according to one or more of the preceding claims, characterized in that it comprises:

a position sensor configured to detect the position of the nail (C) with respect to the element to be nailed or the position of the plunger (30) with respect to the clamp (40); and

a programmable electronic control unit configured to control the linear actuator (20, 120) as a function of the position detected by the position sensor.

12. A nailing machine for nailing wood elements on multiple layers, comprising a resting surface for the element to be nailed and a nailing unit (1, 1') according to any one of the preceding claims, arranged above said resting surface.

Drawing