Patent ID: 12194553

DETAILED DESCRIPTION

The invention relates to a weld cutting machine1comprising cutting jaw parts4,5, which machine may be lighter than known machines. InFIG.1there is shown a perspective view of an exemplary welding machine1that may be used in together with the invention and inFIG.2there is shown a perspective view of an outgoing part32of an exemplary transmission mechanism3.

In a preferred weld cutting machine1according to the invention, a relatively small high-speed electric motor2operates a transmission mechanism3adapted for the purpose of providing a desired transmission. This transmission mechanism3comprises, two parts. On the one hand, a planetary gear31(inFIG.1, the position of the planetary gear is indicated by the arrow, preferably the planetary gear includes an arrangement, shown inFIGS.3and4) driven by the output shaft312of the motor2and a chain/wheel mechanism32(seeFIG.2) driven by the output342(seeFIG.3) from the planetary gear31. Two cutting jaw parts4,5, a first4and a second5, are aligned on each side of a gap having a central plane M extending transversally in relation to the direction of relative movement of the jaws4,5, which movement is the same as the extension C of a rail part at which the machine is used.

At least one cutting jaw part4,5is movably disposed by means of drive rods6, e.g. having the first cutting jaw part4movable in relation to the second fixed jaw part5. The first cutting jaw part4includes a movable support body40,41,42,43having a transversal movable support plate40with a first set of fixed threaded bushings48attached on a backside in line with a through hole49in the transversal support plate40. Each threaded bushing48interacts with first threads63at a first end62of the drive rod6. A plurality, preferably four, drive rods6are arranged in parallel.

The chain/wheel mechanism is a preferred dividing transmission device32, for dividing the output torque from the, preferably centrally positioned, reduction gear in the form of a planetary gear31to synchronously drive at least two rod6, wherein the at least two rods6extend parallelly along the centre line C and are positioned equidistant from the centre line C. It is evident for the skilled person that various transmissions, e.g. cog wheel train, belt transmission, etc, may be used to achieved basically the same functionality, but a chain/wheel mechanism may provide extra advantages.

The second jaw part5is fixed in relation to a base frame500, including a fixed support body that preferably has the same design as the support body to the first jaw part4, e.g. including a transversal fixed support plate51. The drive rods6extend along the machine through holes58in the fixed transversal support plate51of the fixed jaw part5, further through distances50and then with second end parts60into the transmission mechanism3. A second set of fixed threaded bushings52are attached to the transversal support plate51of the second jaw part5. The fixed threaded bushings52interact with second threads64, positioned at a distance from the first threads63, wherein the direction of the threads63,64are opposite to each other. As a consequence, upon rotation of a drive rod6, the drive rod6will move in the desired direction relative the fixed transversal support plate51of the second jaw part5and at the same time also force the first cutting jaw part4to move in the same direction, thereby either increasing or decreasing the gap, depending on the rotational direction.

The base frame500also includes a fixed housing30,35,36,37of the transmission mechanism3, i.e. the second support body and the fixed housing30,35,36,37are fixedly attached to each other. Inside the housing of the chain/wheel mechanism32there are four drive members61that are in engagement with the second end parts60of each drive rod6arranged to transfer torque from the chain/wheel mechanism32to the drive rods6, preferably by a form-locking shaped part65, e.g. hexagonal interfit.

The output shaft319(labelled inFIG.8, see also the central passage313of the output shaft319, labelled inFIG.2) from the planetary gear31is positioned along a central plane (including the intended line of extension C of a rail) within the fixed housing30,35,37of the chain/wheel mechanism32. The fixed housing30,35,37is arranged with a first transversal wall30providing support for bearings/parts of the transmission mechanism3, e.g. a first supporting structure301for the motor2that is attached to an inner side of the first transversal wall30. Further there is a plurality of second supporting structures302each providing support for a drive member61of a drive rod6.

The drive members61preferably enable the rods6to slide forth and back within them, which preferably is achieved by the use of drive members61that include an outer part of a harder material (e.g. steel, which preferably also is weldable) and an inner part of a softer material (e.g. brass), to thereby enable the form-locking shaped part65of the drive rods6to slide relative the drive members61with low friction and also enable high strength (e.g. steel) chain wheels610to be welded onto the outer periphery of drive member61.

The output342(seeFIG.3, wherein parts of the planetary gear is shown) of the planetary gear31(seeFIG.4) drives a shaft319(labelled inFIG.8, see also the central passage313of the output shaft319, labelled inFIG.2) having two central chain wheels320fixed thereto, e.g. by splines. The central chain wheels320A,320B drive one first chain321each. One first chain321A is driven by a first central chain wheel320A that drives a first output chain wheel610at a first side of the housing30,35,37. A second central chain wheel320B drives the second first chain321B which at the opposite side of the housing325drives a second output chain wheel610. The design is symmetric in relation to a vertical central plane, which provides for balanced reaction forces. Merely one side will be described in the following. The output chain wheel610drives one of the drive rods6and also a coaxial transfer chain wheel630, which is also fixed to the drive member61. The transfer chain wheel630in turn via a second chain323drives a second output chain wheel631. The second output chain wheel631is attached to a drive member61of a second drive rod6on that side. The chain/wheel mechanism32thereby may transfers an output rotating torque to the (torque transmitting) drive members61connected to the second ends60, which thereby rotate the drive rods6synchronously and create a linear motion of the movable jaw part4, partly by movement of the drive rods6themselves, via the fixed threaded bushings52and partly of the movable jaw part4via the bushings48.

InFIGS.3and4the design of the planetary gear31is shown in more detail. The motor2and the planetary gear31are attached to opposite sides of the fixed housing30,35,37. Preferably, the planetary gear31is attached to an outer side of the outer side plate37of the housing, whereas the motor2is attached to the outer side of the inner transversal wall30. Hence the output shaft312of the motor2will pass through the housing, preferably through a central passage313of the output shaft319(labelled inFIG.8, see also the central passage313of the output shaft319, labelled inFIG.2) carrying the two central chain wheels320.

At the outer end of the motor output shaft312there are dents forming a sun wheel314that mesh with dents353at the inner side of planet wheels351of the planet assembly350. The planet assembly350includes three circular planet wheels351symmetrically attached to a planet carrier352, having a central collar354providing support/bearing (not shown). Hence, the planet carrier352may rotate together with the planet wheels351. The planet wheels351at their outer sides mesh with dents of a fixed ring wheel (not shown) and also with dents341of a rotatable ring wheel340. The rotatable ring wheel340is non rotatably attached via dents341at its inner periphery to a shaft319(labelled inFIG.8, see also the central passage313of the output shaft319, labelled inFIG.2) carrying the two central chain wheels320and thereby drives the chain/wheel mechanism32.

In the preferred embodiment the planetary gear is a harmonic gear, i.e. the rotatable ring wheel340and the fixed ring wheel have different amounts of dents, e.g. 51 and 48 respectively, which provides for a drastic reduction of the rotational speed from the motor shaft312to the rotatable ring wheel340. In an exemplary embodiment the number of dents of the motor shaft312is 6 and each planet (3 pcs) has 22 dents. In combination with a ring wheel (first outer ring) that is fixed having 48 dents and a rotatable ring wheel340(second outer ring) having 51 dents there will be achieved a gear ratio of 1:153, i.e. when the sun wheel314has made 9 turns, each planet has made one turn (360 degrees) and thereby have driven the rotatable outer ring 1/17 of a turn.

Thanks to the transmission mechanism3and its combination of the (preferably harmonic kind) planetary gear31and the chain/wheel mechanism32, a reliable and compact torque transfer/rotational motion is provided to the drive rods6.

The use of an electric motor2may further provide the advantage that an adaptive torque/speed is automatically created to the drive rods6, in that the higher the resistance the lower the transmitted speed to the drive rods6, i.e. when the resistance increases the rotational speed is reduced and the torque of the motor2increases and thus the force that effect the moving jaw4. Preferably an outboard electric motor2is used that may provide a larger torque than traditional motors.

Furthermore, there is shown that there is a kind of base frame500that fixates basics parts of the weld cutting machine1; the fixed supporting structure including the transversal support plate51, the electric motor2, the fixed housing30,35,37of the chain/wheel gear32, the planetary gear31and other parts that need to be fixated at least in one direction in relation to the second jaw part5. Moreover, the base frame500also has handles7attached thereto for ease of carrying and lifting the weld cutting machine1. At the outer side of the outer plate37of the chain/wheel gear housing there is an expandable protection devise9, having a protecting plate at the outer end and resilient, expendable rubber membrane enclosing a space. This protective device9enables the drive rods6to move out from the fixed housing30/35/37and to be protected from dirt and dust, entering into the space.

Moreover, as schematically shown inFIG.5there may be adjustable guide members8arranged at each jaw part4,5. There are two such adjustable guide members8arranged at each of the jaw part4,5. Each adjustable guide member8includes an adjustable rod81, preferably threaded810, that passes through a passage in a pivotable body83. The adjustable rod81has an adjustable abutment member82, preferably in the form of a nut that interacts with the pivotable body83. At the lower end of the adjustable member81, there is attached a guide member86(making it and the rod L-shaped), which guide member86is intended to enable gripping underneath the head of a rail600to safeguard that the weld cutting machine1is appropriately guided along the rail during the cutting process. Each adjustable rod81may be rotated 90 degrees, preferably by means of a wheel member87at the top of each rod81, such that the guide member86may be moved in and out from a position underneath the rail head (see left hand view inFIG.5) and parallel with the rail (see left hand view inFIG.5) to not grip under the rail600. Abutting jaw surfaces400that interact with abutting sides860of the guide member86assist in correct positioning. Furthermore, each pivotable body83is arranged with handle84,85(seeFIG.1). By means of pivoting the handle84,85from an active position (See position of handle85inFIG.1) to an inactive position (see position of handle84) the adjustable member81with the guide member86will be moved from a gripping position to an un-gripping position, which is achieved by having a camming action by the pivotable body83between an upper contact surface420of each jaw4,5and a lower contact surface820of each adjustable abutment member82, i.e. a larger cross sectional measure Y1in the active position than the cross sectional measure Y2in the inactive position. Thanks to this arrangement the weld cutting machine1can be easily mounted and dismounted onto/off a rail600to perform a cutting operation.

In operation, the weld cutting machine1is transported to the weld between two rail parts, which is to be cut. The transportation may easily be performed by carrying the weld cutting machine1by hand, holding in to the handles7. A protective plate36may be arranged at the bottom of the gear will housing30,35,37in order to enable weld cut machine to be put down but also uneven ground without risk of causing damages. The weld cutting machine1is then lifted on to the rail (not shown) having the weld that is to be cut. The handles84,85are then in inactive mode and the guide members86are parallel with the rail600. The weld cutting machine1is positioned such that the weld is positioned in the gap between the two jaw parts4,5, and preferably such that the weld is close to the fixed jaw part5. The rail will fit into the gaps4A,5B of the jaw parts4,5and also in the gap38in the housing30,35,37, which has the form of an inverted U.

A battery, (not shown), which may be carried separately, is positioned in a battery holder34, preferably positioned on top of the housing30,35,37. The battery provides power to the electric motor2and also a control unit33, e.g. attached to upper side of the housing30,35,37. Further, the adjustment members8are activated by first turning the wheel members87to turn the guide members86and thereafter pivoting the handles84,85into the active position, i.e. by pivoting downwards. Now the adjustable abutment member82is turned until the guide members86contact and grip under the rail head.

In a next stage the adjustable abutment member82is turned to obtain a desired play during cutting, e.g. about 1 mm, and then the adjustable rod81is pushed down to again obtain contact with the lower contact surface820on the pivotable body83. Hence, now the guide members86have been positioned into a desired guiding position underneath the head of the rail600. Hence, an appropriate clearance between the surfaces of the rail and the guide members86, e.g. about one millimeter, is provided for by adjusting the adjustment member86. Now the weld cutting machine1is ready to be operated. Once the machine is started the electric motor2starts spinning whereby the rotation will be transmitted first to the planetary gear31and then to the chain/wheel gear32to rotate the drive rods6, whereby the movable jaw part4will start moving towards the weld that is to be cut. Preferably a harmonic planetary gear is used that provides a gear ratio of at least 1:100 and an electric motor2rotating with at least 3000 rpm, preferably about 4000-6000 rpm. The electric motor2will quickly move the movable jaw part4in a first stage when there is no resistance and move it more slowly once resistance is encountered when the jaw front46meets the weld, thereafter the two jaw fronts46,56will move towards each other to cut the weld, which is achieved when the two jaw fronts46,56meet each other.

Thereafter the weld cutting machine is easily dismounted by pivoting the handles84,85, such that the guide members86get out of contact with the rail head. Then the wheel members87may be easily turned to position the guide members86parallel with the rail600, whereby the machine1is free to be lifted up from the rail.

The above exemplified solution of machine1means that the jaw parts4,5may be moved relatively quickly along the rail surface towards the weld joint with relatively little force and that as soon as the movable jaw4, with the firm jaw engaging from the other side engages the weld joint, the speed will be lowered, and the torque/force will be increased and adapted to the need. Maximum power produced by a well-functioning prototype is above 10 tonnes, preferably above 12 tonnes. Thanks to the construction, a machine1may be obtained having about half the weight, about 25 kg, compared with known hydraulic machines that weigh about 50 kg.

As is shown inFIG.1the cutting jaws4,5may be divided into jaw fronts46,56being wear sections and support sections57,47, respectively. Thanks to the division several advantages may be gained. Firstly, a lighter and less expensive material can be used in the support sections57,47, i.e. making the machine, as a whole, less heavy. Secondly the coupling surface between jaw fronts56,46and support sections57,47can be designed so that heat expansion can occur between them, implying that the jaw fronts56,46may be made in materials optimized for cutting without any need of compromise in relation to difference regarding heat expansion, which is a problem in known wedge cutting machines, i.e. cutting at high speed may lead to heat cracks. Thirdly, a cheaper wear section may be obtained, since the kind and amount of material in the easily exchangeable wear section may be optimized in regard to cutting as such. In addition, the coupling surface (not shown) between the jaw fronts and support sections according to a preferred embodiment can be designed so that a change can be made very quickly and easily, only by means of shape fitting, that is, without the need for a screw joint, which eliminates the need for time-consuming release and fixation of wear parts.

InFIGS.6and7there is shows a preferred embodiment of a jaw front46according to the invention. As noted inFIG.6the width W of the jaw front is relatively small, i.e. in the range of 10-40 mm, more preferred 25-30 mm.

It is evident for the skilled person that the novel cutting jaws4,5, divided into jaw fronts56,46being wear sections and support sections57,47, respectively, may also be used together with weld cutting machines of other kind, i.e. in place of homogeneous jaws. Also, the adjustable fastening device8for fixing the machine1to a rail, including an easily handled pivot mechanism83enabling easy and safe locking and unloading of the machine1, may of course also be used together with other weld cutting machines.

InFIG.8there is shown schematic perspective view of a modified transmission arrangement according to the invention. A major difference compared to the above-described embodiment of the invention is that the rods6in this embodiment do not rotate but are stationary. As an exemplary solution to keep the rods6stationaryFIG.8shows the use of locking members67that are fitted to the end parts60of each pair of rods6. Accordingly, there is one locking member67at the righthand pair of rods6and a second locking member67, of exactly the same kind, that locks the rods6of the left-hand pair. The locking function is achieved by having form shaped fit between each rod end60of the rods6having a corresponding shape (male/female or vice versa) as the solid locking member67, e.g. heaxagonal. Accordingly, each locking member67has first and the second locking member67A,67B that interfit with the end part60of each one of a pair of rods6. In between the locking members67A,67B there is a solid body67C that keeps the members67A,67B in fixed positions. Accordingly, the locking members67safeguard that no rotation is possible for any of the rods6.

Further, as presented above the rods are arranged with driving threads64, for transfer of movement of one of the cutting jaw parts4,5. In this embodiment it will be the second cutting jaw part5that will move along the rods6. This movement is achieved by rotating the drive member620which are fixedly positioned within the second cutting jaw part5by means of bearings (not shown). The drive members620are preferably made in a material that is of a different kind than the material in the rods6, e.g. brass, in order to provide for low friction but for the skilled person it is evident that different kind of materials may be used for the drive members620, e.g. also of same material, to fulfil the desired basic function, by use of appropriate lubrication. By use of brass in the drive members620lubrication may be eliminated, which is an advantage in respect of several aspects. The drive members620may be driven by various appropriate transmission mechanisms.

As already described above a preferred transmission mechanism could be chain gears320,321,323, to transmit, torque and rotation from the central output wheel320. As it's indicated inFIG.8, the central driving wheel320is mounted on output shaft319, by means of splines, to transmit torque/rotation from the output of the reduction gear31. Two identic chain wheels320A,320B, drive one chain each321A,321B that in turn drive one identic second chain wheel610each fixedly attached to a first drive member620on a first rod6within each pair of rods6. The torque/rotation is thereafter also transmitted to the second rod6within each pair of rods6by means of second chains323. A third chain wheel630parallel to the input wheel610is attached to the first drive members620. Each second chain323is connected the third chain wheel630and also to a fourth chain wheel631that is fixedly attached to a second drive member621. Accordingly, there are four drive members620,621each being rotated synchronically. As a result, the rods6will be sliding forth and back by means of rotating the drive members620,621to thereby increase and decrease the gap between the jaw parts4,5according to the invention. In this embodiment the first jaw part4is fixedly attached to the rods6at one end, opposite to the end having the locking member67, by means of fixation threads63. Nuts may by threading onto the threads63clamp the second jaw part4tightly in contact with supporting collars66on the rods6. Accordingly, the first jaw part4is securely fixed and connected to one end of the rods6.

The invention is not limited by the embodiments presented above but may be varied within a plurality of aspects without departing from the basic principles of the invention. For instance, it is evident that instead of using a separate shaft319it may be integrated with the planetary gear31and/or the drive wheels320. Further, if using a cog wheel train instead of a chain transmission it may suffice with one single outgoing member320. It is foreseen that some of the aspects described above may be the subject for their own protection by one or more divisional applications, e.g. the use of separate wear parts, which may not be limited to a weld cutting machine according to the invention but may also be used in other kind of weld cutting machines.