LOG CUTTING MACHINE

Abstract: The present specification discloses a log cutting machine. Known machines are relatively slow in operation. The present invention provides a cutting machine which has a cyclic operation and which can therefore be operated at fast speeds relative to the prior art machines. The machine of the present invention comprises a pivotal support (1) which carries a cutting blade (5), the cutting blade (5), in use, acting with a reaction surface (41) to produce the required cutting action, said support (1) being pivotal by a cranked drive (13,29) via a sliding mechanism (7,27)

Description: The present invention relates to a log cutting machine. In particular the present invention relates to a mechanically powered log cutting machine for cutting and processing timber into logs for use, for example, as firewood. Various machines already exist for cutting and processing logs. Predominantly circular saws are used with a number of modifications to enhance operator safety. These circular saws are often used in conjunction with a hydraulically powered splitting device which is used to reduce large diameter logs to a usable size. Hydraulically powered guillotines are also used to cut through large boughs and/or tree trunks. However, whilst each of the above known machines are effective in their own way, they are relatively slow in their cutting action. The aim of the present invention is to provide a log cutting machine which provides a cyclic cutting action which is rapid in comparison with the above prior art machines. According to the present invention there is provided a log cutting machine comprising a pivotal support carrying a cutter blade, connecting means being movably connected to both a cranked drive and said pivotal support for effecting cyclic pivotal movement of the cutting blade towards and away from a reaction surface, characterised in that the reaction surface is defined by two spaced apart oppositely inclined back-to-back ramps defining a gap therebetween, said cutting blade being movable into the gap between the ramps of said reaction surface upon pivoting of the support. In a preferred embodiment of the present invention the pivotal support comprises two parallel bars on which a sliding mechanism is mounted, the bars being joined together at each end region so as to form a support for the cutting blade at one end of the pivotal support and a pivot point at the other end. The pivot point is pivotally carried on a general framework for the machine with the cranked drive connected to said sliding mechanism also supported on said framework. The cranked drive may be designed for circular or elliptical motion. Rotation of the cranked drive by either a suitable motor carried by the framework or, for example, by a power take-off of a tractor carrying the framework, causes the pivotal support to pivot about said pivot point, the sliding mechanism moving back and forth along the parallel bars. The pivotal motion moves the cutting blade towards and away from the reaction surface. By using back-to-back inclined ramps to form the reaction surface, the severed logs fall away as they are cut, obviating the danger of the cutting blade jamming between severed parts of a log, as can happen when an extensive planar reaction surface is provided. Preferably an energy storage device in the form of a leaf spring is also mounted on the framework, the end regions of the leaf spring being connected to the framework with the middle region pivotally connected to an extension of the pivot point region of said pivotal support for the cutting blade. Thus, as the cranked drive operates to move the cutting blade away from the reaction surface the leaf spring is tensioned by the drive, the energy thus stored in the spring being released as the cranked drive moves the cutting blade towards the reaction surface in a cutting stroke; the energy released enhancing the power of the cutting stroke. In use, the cutting blade moves continuously towards and away from the reaction surface. Thus, as the blade clears the diameter of a log being processed, during its movement away from the reaction surface, the log can be manually or mechanically moved axially through a required axial distance under the path of the cutting blade. The cutting stroke powered by the drive and the energy storage device, then severs the required log length and the log can be subsequently moved axially as the blade moves away from the reaction surface. Advantageously an endless conveyor can be positioned adjacent to one side of the reaction surface so as to convey logs away from the machine to a desired location as they are cut. Preferably the conveyor is driven by the same motor as the cranked drive. The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which:- Fig 1 is a schematic illustration of the present invention; and Fig 2 is a diagrammatic side view of part of a one embodiment of the present invention. Fig 3 is a perspective view of a part of a preferred embodiment of the present invention; and Fig.4 is a side view of the preferred embodiment of Fig.3. As seen in Fig.1 of the accompanying drawings, the log cutting machine of the present invention comprises a pivotal support 1 which is pivotally carried at one end on fixed point 3, a cutting blade 5 being mounted on the other end region of said pivotal support 1. A sliding mechanism 7 is slidable back and forth along part of said pivotal support and is connected to a crank drive 9 comprising an elongate arm 11 pivotally connected to the sliding mechanism 7 and fixedly connected to a drive axle 13. Rotation of the drive axle 13 by suitable motor means thus causes the pivotal support 1 to pivot back and forth in directions 'A' and 'B' respectively; the sliding mechanism 7 moving in directions 'X' and 'Y' respectively. As the pivot support 1 moves in direction 'A' away from reaction surface 15, an energy storage device in the form of a spring 17 is tensioned, energy being thus stored in the spring 17. Thus, when the pivotal support 1 is moved in direction 'B' towards the reaction surface 15 to perform a cutting stroke, the energy stored in the spring 17 is released to add to the power of the crank drive 9, thus improving the power of the cutting stroke. In the embodiment of the present invention illustrated in Fig.2 of the accompanying drawings, the same reference numerals as used in Fig.1 will be used to indicated equivalent components. The pivotal support 1 in the embodiment of Fig.2 basically comprises two parallel bars 19 inter-connected at one end to form a pivot point region 21 and interconnected at the other end to form a cutting blade support 23. The cutting blade support 23 is formed with an inverted U-shaped recess 25 which effectively limits the maximum diameter of log to be cut, and across the mouth of which the cutting blade 5 extends. The cutting blade 5 is preferably tensioned along its length to reduce the likelihood of deflection during a cutting stroke. The sliding mechanism 7 is slidable back and forth on both parallel bars 19 and incorporates the crank drive 9. The sliding mechanism 7 essentially comprises an open-ended generally cylindrical housing 27 having two lateral extensions 28, each extension 28 having a bore through which a bar 19 axially slidably extends. A circular disc-like drive member 29 is rotatably located and retained within a complementary cavity or recess in the housing 27 and together with a drive axle 13, forms said crank drive 9. The drive axle 13 is fixedly secured to the drive member 29 so as to extend axially of the disc-like drive member 29 from a position offset from the centre of the disc-like drive member 29, and is rotatably mounted at a fixed point in a framework 31 to which the pivot point region 21 is likewise connected. Thus, by connecting a suitable drive, e.g. a motor mounted on the framework or a power take off of a tractor, to the drive axle 13 via a suitable reduction gear 47 (see Fig.4), the drive member 29 and housing 27 move eccentrically causing the sliding mechanism 7 to move likewise, resulting in the pivotal support 1 pivoting in directions 'A' and 'B' sequentially. The energy storage device is in the form of a semi-elliptical leaf spring 17 which is pivotally connected at one end, as at 33, to the framework 31, and engaged against a roller stop 35 on the framework 31, at its other end region. The middle region of the spring 17 is pivotally connected by a mechanical linkage 37 to an extension 39 of the pivot point region 21 of the pivotal support 1. Thus, as the pivotal support 1 is pivoted in direction 'A', the spring 17 is tensioned, i.e. flexed, said other end region moving over the roller stop 35, and potential energy is stored in the spring 17. When the pivotal support 1 is moved by the drive in direction 'B' towards the reaction surface 15, the power of this cutting stroke is enhanced by the release of the potential energy stored in the spring 17. The reaction surface 15 is provided by two back-to-back inclined ramps of which one is shown at 41. In use, a selected log can be manually or mechanically slid onto the reaction surface in a direction normal to the available pivotal motion, the log being moved under the cutting blade 5 as the blade 5 clears the log during its movement in direction 'A'. The subsequent cutting stroke in direction 'B' , powered by the drive together with the energy stored in spring 17, then slices through the log, the inverted U-shaped recess 25 engaging around the log and dictating the maximum diameter of log which can be processed. Whilst a suitable motor can be mounted on the framework 31 and connected to the drive axle 13, it is envisaged that the machine may more usefully be mounted on the rear of a tractor with the drive axle 13 coupled to the tractor power take off via a suitable reduction gear as shown in the preferred embodiment of Figs. 3 and 4. In this way the machine can be taken to a desired site to process logs, as required. The preferred embodiment of Figs. 3 and 4 has basically the same internal structure as shown diagrammatically in Fig. 2, and like reference numerals will be used in Figs. 3 and 4 to identify equivelant parts. As shown this preferred embodiment is mounted on the rear of a tractor 43 and a drive shaft 45 connected to the power take-off of the tractor 43 connects with a reduction gear 47 which drives the drive axle 13. The reduction gear 47 connects with one end region of the drive axle 13 and the other end region of the drive axle 13 drives an endless chain (not shown) within casing 49, the endless chain driving an endless conveyor 51, one end region of which is located adjacent to one side of the reaction surface 15. In this way the endless conveyor 51 is powered by the tractor power take-off, and logs can be conveyed sequentially away to a desired location immediately they have been cut. Further to strengthen the support of the cutting blade 5, the generally rectangular blade is located in a slot 52 on the pivotal support 1 so that it is engaged along the length of its rear edge, and the blade is tensioned along its length by suitable sever means. The reaction surface 15 with which the cutting blade acts is formed by two oppositely inclined surfaces 53 with a gap 55 formed therebetween. These inclined surfaces 53 and gap 55 are formed by two back-to-back ramps 57, the cutting balde 5 moving into the gap towards the end of its cutting stroke. Thus the severed part of a log can pull away as it is cut, thereby avoiding jamming the entry of the cutting blade 5 into the gap 55 ensures a complete cut at all times. Whilst the above desired embodiments utilise a crank drive having a circular motion, a crank drive having an elliptical motion can equally well be substitued, if desired. The present invention thus provides a simple log cutting machine which can be efficiently used to cut logs from any selected raw materials.

Claims: A log cutting machine comprising a pivotal support (1) carrying a cutter blade (5), connecting means (7) being movably connected to both a cranked drive (9) and said pivotal support (1) for effecting cyclic pivotal movement of the cutting blade (5) towards and away from a reaction surface (15) , characterised in that the reaction surface (15) is defined by two spaced apart oppositely inclined back-to-back ramps (53) defining a gap (55) therebetween, said cutting blade (5) being movable into the gap (55) between the ramps (53) of said reaction surface (15) upon pivoting of the support (1). A machine as claimed in claim 1, wherein the pivotal support (1) includes two parallel bars (19) on which a housing (27) is slidably mounted, said housing (27) and said bars (19) forming said connecting means (7), adjacent end regions of the parallel bars (19) being joined together with one end region (23) of the thus formed support (1) carrying the cutting blade (5) whilst the other end region (21) is attached to a pivot point (3). A machine as claimed in claim 2, wherein the pivot point (3) is carried in a general framework (31) of the machine with the cranked drive (9) also supported on said framework (31). A machine as claimed in claim 3, wherein the cranked drive (9) comprises a cylindrical cavity in said housing (27), the axis of said cavity extending perpendicular to the said parallel bars (19) with a complementary disc-like drive member (29) being rotatably located and retained in the cavity, said drive member (29) having a drive axle (l3) which extends axially of the drive member (29) from a position offset from the centre of the disc-like drive member (29), through an open-end of the cavity. A machine as claimed in claim 4, wherein the drive axle (l3) is rotatably supported in bearings in said general framework (3l). A machine as claimed in claim 5, wherein the drive axle (l3) is connected to a reduction gear (47) which is adapted to be driven by a power source (45). A machine as claimed in claim 6, wherein the drive axle (l3) can drive an endless conveyor (5l) which can convey cut material away from the region of the reaction surface (15). A machine as claimed in any one of the preceding claims, wherein an energy storage device (17) is attached between a fixed point (33, 35) and the pivotal support (1) so that energy is stored in said storage device (17) as the pivotal support (1) moves the cutting blade (5) away from the reaction surface (15). A machine as claimed in claim 8, wherein the energy storage device is in the form of a spring (17). A machine as claimed in claim 9, wherein the spring is a leaf spring (17) which is pivotally mounted at one end region (33) and engaged against a stop (35) at the other end region, the middle region of the leaf spring (17) being connected to said pivotal support (1).

Inventors: KNIGHT, MAY
Applicants: KNIGHT, DAVID JOHN
Application year: 1987
Main classification: B27L7
IPC codes: B27M1, B27L7