Improved log splitting machine

Abstract

 A log splitting machine comprising a seat (1) for positioning a log between two members of variable distance apart, one of which is fixed and the other is movable along the axis of said seat under the control of a motorized male screw-female screw linkage (110-21) presents means arranged to automatically annul coupling between the male screw and female screw along the final parts of the outward and return strokes of the movable member, and means (22, 23) to ensure engagement between the male screw and female screw at the moment of reversal of rotation of this latter.

Description

[0001] This invention relates to improvements in log splitting machines in which the splitting action on the logs is provided by a motorized male-female screw linkage.

[0002] In short, such log splitting machines usually comprise a virtually horizontal seat in which the log is placed between two members of adjustable distance apart which are under the control of said linkage.

[0003] The purpose of one of said members, hereinafter known as the blade, is to split the log, the purpose of the other, hereinafter known as the log pusher, being to retain the log.

[0004] The blade is normally stationary, as in the example described hereinafter, the log pusher being made to slide forwards and rearwards along the axis of said seat by said linkage.

[0005] In such log splitting machines, the male and female screw are constantly mutually engaged, with the consequent danger of damaging impact between the log pusher and fixed parts of the machine if the linkage is not halted in time at the ends of the outward and return stroke of the log pusher.

[0006] Again, in such known log splitting machines the male and female screw can irreversibly lock together if a particularly resistant log is present. The reason for this is that along the linkage between the male screw and the drive motor, means are not provided to limit the force with which the male screw drags the female screw. The main object of the present invention is to provide means for obviating the aforestated problem within the context of a simple, rational, reliable, durable and low-cost construction.

[0007] Said object is attained by virtue of the characteristics indicated in the claims.

[0008] According to the invention, within the context of a log splitting machine of the type indicated in the introduction, the male screw and female screw are coupled together in such a manner that the engagement between the two is automatically annulled along the final sections of the outward and return strokes of the movable member of the machine.

[0009] Preferably said automatic disengagement is achieved by two smooth cylindrical portions positioned at opposite ends of the male screw, to hence establish the outward and return travel limit of the movable member.

[0010] By this means, said movable member is prevented from interfering with fixed parts of the machine structure.

[0011] In addition, with said smooth cylindrical portions there are associated means, described in detail hereinafter, arranged to ensure that engagement between the male screw and female screw takes place at the moment of reversal of rotation of this latter.

[0012] Again, according to an advantageous characteristic of the invention, a spacer arranged to establish the maximum length of the log to be inserted into the operating seat of the machine is provided to enable the female screw to engage for a sufficient distance with the male screw before the member retaining the log contacts this latter.

[0013] This prevents the threads of the male screw and of the female screw from undergoing damage because of insufficient screwing between the two.

[0014] Finally, according to the invention, along the linkage which connects the drive motor to the male screw there are interposed means for automatically disconnecting said linkage if excessive resistances are present, in order to prevent irreversible locking between the male screw and female screw.

[0015] The constructional characteristics and merits of the invention will be apparent from the ensuing detailed description, given with reference to the figures of the accompanying drawings, which illustrate a particular preferred embodiment thereof by way of non-limiting example.

[0016] Figure 1 is a section on the line I-I of Figure 2, in which the log pusher is at the end of its rearward travel.

[0017] Figure 2 is a plan view of the preceding figure from above.

[0018] Figure 3 is a view in the direction III of Figure 2.

[0019] Figure 4 is a part of Figure 1 on an enlarged scale.

[0020] Figure 5 is a partial view similar to the preceding showing the log pusher at the end of its forward travel.

[0021] Said figures, and in particular Figures 1 to 3, show a horizontal tubular beam 1 of square cross-section positioned on a frame 2 mounted on two wheels 3.

[0022] Above one end of said beam 1 there is positioned a stationary blade 6, in front of which there is a slidable log pusher 66 which will be described hereinafter.

[0023] Beyond said log pusher 66, there is fixed on the opposite end of the beam 1 a protection bousing 4 which is closed by a cover 5 and extends downwards where it is supported by the axle of the wheel 3, and carries fixed thereto the casing of an electric motor 7.

[0024] The output shaft from said motor 7 penetrates into the protection bousing 4 (see Figure 1) where it presents a pinion 8 which engages the larger-diameter toothing of an overlying double gearwheel 9, the lesser-diameter toothing of which engages an overlying cup-shaped idle gearwheel 10.

[0025] Said idle gearwheel 10 is slidingly mounted, by means of a suitable bush, on the smooth projecting part of a threaded shaft 11 which is housed in the beam 1, as described hereinafter. On said projecting part there are mounted, proceeding from said gearwheel 10 towards the cover 5, a thrust bearing 12, a pack of spring washers 13, a washer 14 and a self-locking nut 15.

[0026] The shaft 11 is rotatably mounted on the rear side of the protection housing 4 by means of the ball bearing 16, between said bearing 16 and the gearwheel 10 there being interposed a friction ring 17 which is keyed onto the shaft 11 and is received in the cavity of said cup shape.

[0027] That end of the beam 1 which faces the protection housing 4 is provided with a centrally holed plate 18 to which said protection housing 4 is fixed, and against which a flanged thrust bush 20 rests by way of an interposed thrust bearing 19.

[0028] The bush 20 lies between the inner ring of the bearing 16 and a shoulder of the shaft 11, of which the projecting part lying within the beam 1 comprises: a central threaded portion 110 (or male screw), two smooth intermediate portions 111 having a diameter practically equal to the base diameter of said threaded portion 110, and two cylindrical terminal stems of diameter slightly less than said intermediate portions 111.

[0029] An internally threaded nut 21 (or female screw) having a length slightly greater than that of said intermediate portions 111 engages said threaded portion or male screw 110, respective compressed springs 22 and 23 being mounted on said terminal stems 112.

[0030] Specifically, the first 22 of said springs, to the right in Figures 1 and 4, lies between a thrust ring 24 and the bush 20, while the second spring 23, to the left in Figures 1 and 5, lies between two thrust rings 25, the outer of which is retained by a split ring 26.

[0031] As can be seen in Figures 1, 4 and 5, the beam 1 receives internally, as a free sliding fit, a tube 27 of square cross-section containing a tube 28 of circular cross-section the inner diameter of which is greater than the outer diameter of the shaft 11.

[0032] The round tube 28 is shorter than the square tube 27, and can move together with it as will be apparent hereinafter.

[0033] The female screw 21 is inserted practically as an exact fit into that end of the square tube 27 which faces the protection housing 4, and lies between the corresponding end of the round tube 28 and an annular stop 29 fixed to the end of the square tube 27.

[0034] The other ends of said tubes 27 and 28 are disposed flush with each other, there being inserted into the inner tube a ring 30 for supporting the structure which drags the log pusher 66.

[0035] Said three elements 27, 28 and 30 are provided with aligned transverse holes with which a through bolt 31 is engaged with a certain radial clearance.

[0036] Said dragging structure is a U-shaped structure and as can be seen in Figure 2 comprises a robust transverse plate 32 which abuts against the ends of the tubes 27 and 28, and carries fixed to it said ring 30 and two longitudinal flat bands 33 positioned along the sides of the beam 1 and terminating with two salient shoulders 34 to which the log pusher 66 is fixed.

[0037] In particular, from the upper edges of said flat bands 33 there branch two diverging flanges 330 which, in combination with the upper wall of the beam 1, provide a cradle for supporting the logs to be split.

[0038] The log pusher 66 is shaped as a horizontally extending channel which is disposed transversely to the beam 1, has its mouth facing the protection housing 4, and has its lower wall spaced from the upper face of the beam 1.

[0039] On the log pusher 66 there is slidingly mounted, on that side facing the blade 6, a channel-shaped member 35 acting as a spacer, its lower wall resting on the beam via the shoe 36, and extending towards the protection housing 4 where it presents an anti-withdrawal screw 37.

[0040] Finally, when the log pusher 66 is in its maximum withdrawal position shown in Figures 1 and 2, with the nut disengaged from the threaded portion 110 of the shaft 11, said lower wall of said spacer 35 rests against the protection housing 4, such that the front wall of said member 35 extends beyond the front wall of the log pusher 66 by an amount of the same order of magnitude as the length of the nut 21.

[0041] As can be seen in Figure 1, it should also be noted that that upper part of the protection housing 4 facing the upper face of the beam 1 presents an inclined wall which blends into the rear side of said protection housing 4 in a position corresponding with said upper face of the beam 1.

[0042] The invention operates as follows.

[0043] Having loaded a log onto the beam 1, the maximum length of which is determined by the distance between the blade 6 and the spacer 35, the operator (using both hands for questions of safety) starts the motor 7 which rotates the shaft 11 via the gear train 8-10 and the friction clutch device 10, 17.

[0044] Because of the thrust of the spring 22, the female screw mounts the male screw 110 without problem and advances to drag with it the log pusher 66 by virtue of the thrust of the female screw 21 on the round tube 28 which in its turn presses against the plate 32. The square tube 27 follows the round tube 28 because of the bolt 31, and the log pusher 66 becomes increasingly inserted into the spacer 35.

[0045] After a certain travel without load, the log pusher 66 rests against the spacer 35, which then pushes the log against the blade 6.

[0046] If the log offers considerable resistance the friction clutch unit 10-17 operates to prevent irreversible locking between the male screw 110 and female screw 21, and enable the operator to return the assembly to its starting configuration and arrange the log differently, to then again advance the log pusher.

[0047] On reaching the position of Figure 5, the log pusher stops by disengagement of the female screw 21, and maintains the position attained even if the shaft 11 continues to rotate.

[0048] On reversing rotation of the shaft 11, the spring 23 causes the female screw 21 to mount the male screw 110, with which the female screw 21 retracts to pull the square tube 27 by virtue of the stop 29, said square tube 27 dragging in its turn the round tube 28 by virtue of the bolt 31.

[0049] At the commencement of this return stroke the log pusher 66 withdraws from the spacer 35 until it rests against the male screw 37, by means of which the log pusher 66 returns the spacer into proximity with the protection housing 4.

[0050] It should be noted that the advantageous presence of the inclined wall provided at the top of the protection housing 4 and facing towards the beam 1 means that an object, such as a log rested inadvertently on the rear end of the beam 1, is made to fall off on termination of the rearward stroke of the log pusher 66 instead of remaining inconveniently locked between the log pusher and the protection housing.

[0051] Maximum withdrawal of the spacer 35 into the position shown in Figure 1 is achieved either directly by hand or by the next log to be split resting against it.

[0052] The merits and advantages of the invention are apparent from the aforegoing and from an examination of the accompanying figures.

[0053] The invention is not limited to that illustrated and described, but comprises all the technical equivalents of the invention, and their combinations, if implemented within the context of the following claims.

[0054] For example, there is nothing to prevent the inner thrust rings 24 and 25 for the springs 22 and 23 when in their completely extended configuration being made to rest directly against the opposing ends of the male screw 110.

[0055] In addition, of the blade 6 and the log pusher 66, one can be movable and the other stationary, and an elastic repositioning member can be interposed between the log pusher 66 and the spacer 35.

[0056] Again, the spacer can assume other forms. For example it can be fixed, and consist of a horizontal push rod positioned parallel to the beam 1, and having its rear end fixed to the corresponding end of the beam 1 and its front end passing through an aperture provided in the log pusher 66 in order to extend beyond its active face when retracted as in Figure 1.

Claims

1. A log splitting machine comprising a seat (1) for positioning a log between two members of variable distance apart, one of which is fixed and the other is movable along the axis of said seat under the control of a motorized male screw-female screw linkage (110-21), characterised by comprising means arranged to automatically annul coupling between the male screw and female screw along the final parts of the outward and return strokes of the movable member, and means (22, 23) to ensure engagement between the male screw and female screw at the moment of reversal of rotation of this latter.

2. A log splitting machine as claimed in claim 1, characterised in that said decoupling means comprise two cylindrical portions (111) positioned at the front end and rear end of the male screw, and having an outer diameter practically equal to the inner diameter of the female screw (21).

3. A log splitting machine as claimed in claim 2, characterised in that said cylindrical portions have a length of the same order of magnitude as the female screw.

4. A log splitting machine as claimed in claim 1, characterised in that said engagement means consist of elastic members.

5. A log splitting machine as claimed in claim 4, characterised in that said elastic members comprise two compressed springs mounted on respective smaller-diameter cylindrical stems representing a direct extension of said cylindrical portions, to maintain respective thrust rings constantly forced towards the shoulders which exist between said stems and said cylindrical portions.

6. A log splitting machine as claimed in claim 1, characterised in that a spacer for establishing the maximum length of said log is associated with that machine member for retaining the log during splitting, in order to enable the female screw, before contact between the log and said retention member, to screw onto the male screw by a distance at least of the same order of magnitude as the length of the female screw.

7. A log splitting machine as claimed in claim 6, characterised in that said spacer comprises a body provided with an abutment which is arranged to pass beyond and to release the active part of said retention member during the log loading stage and during the log splitting stage respectively.

8. A log splitting machine as claimed in claim 1, characterised in that along the linkage which connects the male screw to the drive motor there are interposed means arranged to automatically disconnect said linkage if excessive resistances are present.

9. A log splitting machine as claimed in claim 8, characterised in that said means consist of a friction clutch device.

Drawing