Bandsaw
United States Patent [1 1 Aizawa BANDSAW {75] Inventor: Tsuneo Aizawa, Hiratsuka, Japan [73] Assignee: Amada Company Limited,  
 Isehara-shi, Kanagawa-ken, J apan [22] Filed: June 7, 1973 [21] Appl. No.: 367,895  
 [30] Foreign Application Priority Data June 7, i972 Japan 47-66306 [52] U.S. Cl. 83/360; 83/527; 83/800; 83/801; 83/813 [51] Int. Cl 823d 53/04 [58] Field of Search 83/360, 527, 799, 800, 83/801, 8l3, 554  
 [56] References Cited UNITED STATES PATENTS 3.72l.l39 3/l973 Robinson 83/360 X Primary Examiner-J. M. Meister Attorney, Agent, or Firm-Thompson, Birch, Gauthier &amp; Samuels 1 Apr. 8, 1975 [57] ABSTRACT A bandsaw machine is provided with a device in which a check valve having a tappet or projection and a flow control valve are provided in parallel with each other in a hydraulic passage connecting a hydraulic pump with a hydraulic cylinder for raising a cutting head holding a bandsaw blade, a micro switch is electrically connected with an electric motor for driving said pump and a solenoid operated valve for controlling hydraulic fluid through a time limit switch, a vertical elongate rod is vertically movably mounted on a part of said cutting head and is provided at its bottom end with an horizontally elongate plate which is touchable with a material to be cut, a horizontal elongate plate is fixed to the top end of said vertical elongate plate so as to depress said tappet or projection of said check valve and actuate said micro switch. The vertical elongate rod is so designed as to be brought into and out of contact with the material to be cut in order to automatically determine the upper limit of the vertical movement of the bandsaw blade and automatically control the lowering speed of the bandsaw blade during its idle time.  
 3 Claims, 4 Drawing Figures IEUAPR 81975 SEZEU 1 (IF 2 FIG 4 BANDSAW BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to so-called horizontal bandsaw machines in which a cutting head or frame is lowered to cut a material, and pertains more particularly to horizontal bandsaw machines which have been provided with a novel device for automatically minimixing the idling of the bandsaw blade.  
 2. Description of the Prior Art In a so-called horizontal bandsaw machine wherein a cutting head or frame holding a bandsaw blade is lowered to cut a material, it is desirable to minimize the upand-down movement of the cutting head in order to minimize the idling of the bandsaw blade. Namely, it is important to make the upper limit of the vertical movement of the bandsaw blade as low as possible, depending upon the height or diameter of the material to be cut. On the other hand, the upper limit of the vertical movement ofthe bandsaw blade has to be made a little higher than the top surface of the material to be cut so as to prevent the bandsaw blade from being damaged by the material when the latter is being fed, since most of the materials are not exactly straight but uneven.  
  For the above-mentioned reasons, conventional bandsaw machines have been provided with mercury switches or limit switches and have been so designed that the upper limit of the vertical movement of the bandsaw blade is located a little higher than the top surface of the material to be cut.  
  All of such conventional bandsaw machines, however. have a number of drawbacks or disadvantages associated therewith. It has been very difficult to accurately determine the upper limit of the vertical movement of the bandsaw blade by means of the mercury switches and it has been required to raise and lower the cutting head in a tentative way before actually beginning the cutting operation. Also. it has been very troublesome to adjust the position of the limit switches so as to set the upper limit of the bandsaw blade according to the height or diameter of the material to be cut.  
  Furthermore, a great disadvantage with the conventional bandsaw machines has been that the bandsaw blade is not lowered faster during its idle time when the bandsaw blade is only lowering from its upper limit of vertical movement towards the material to be cut without making any cutting operation.  
 SUMMARY OF THE INVENTION It is an object of the present invention to provide a horizontal bandsaw machine which is so designed that the upper limit of the vertical movement of the bandsaw blade is automatically determined according to the height or diameter of the material to be cut so as to minimize the idling of the bandsaw blade.  
  It is another object of the present invention to provide a horizontal bandsaw machine provided with a novel device for automatically lowering the bandsaw blade at a faster rate during its idle time when it is only lowering from its upper limit of the vertical movement towards the material to be cut without making any cutting operation so as to further minimize the idling of the bandsaw blade.  
  Other and further objects of this invention will be apparent from the following description and accompanying drawings which. by way of illustration. show the preferred embodiment of the present invention and the principle thereof.  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a front view of a horizontal bandsaw machine embodying the principles of the present invention.  
  FIG. 2 is an enlarged view showing a major portion of the device in accordance with&#39;the present invention.  
  FIG. 3 is a sectional view taken substantially along the line IIIIII of FIG. 2.  
  FIG. 4 is a diagrammatic illustration of the hydraulic components of the bandsaw machine embodying the principles of the present invention, showing the cutting head of the machine as having been raised to its uppermost position.  
 DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be particularly described with reference to the accompanying drawings.  
  In a horizontal bandsaw machine shown in FIG. 1, a cutting head or frame 1 enclosing therein a bandsaw blade 3 trained over a driving wheel 5 and a driven wheel 7 is pivotally mounted on a base 9 by means of a hinge pin 11 so as to be swung up and down by a hydraulic cylinder 13 mounted on the base 9. Two saw guide arms 15 and 17 holding saw guides 19 and 21 respectively are slidably mounted on a guide plate 23 horizontally fixed to an upper portion of the cutting head or frame 1 and are tightened by knobs 25 and 27. A vise 29 having vise jaws 29jr and 29jl is mounted on the base 9 to hold a material M to be cut. A control box 31 is mounted on the top of the bandsaw machine to house electric and hydraulic components. As is readily apparent. the bandsaw blade 3 is driven by the driving wheel 5 and lowered together with the cutting head 1 to cut the material M with the guide of the saw guides 19 and 21.  
  As viewed in FIGS. 1 and 2, the right-hand saw guide arm 15 is provided on its left side with a wide projection 15wp which is formed some distance away from the guide plate 23 as viewed in FIG. 3. On the backside of the wide projection 15wp of the saw guide arm 15 are a plurality of rollers 33, 35, 37 and 39 which are rotatably supported by their respective shafts 33&#39;, 35&#39;, 37&#39; and 39&#39; secured to the wide projection 15wp.  
  Vertically slidably mounted between the rollers 33, 35, 37 and 39 is an elongate square rod 41 having on both its sides vertical elongate grooves 41gr and 41g! in which the rollers are received to guide the square rod 41. The square rod 41 is provided at its lower end with a horizontally extending angled plate 43, the major portion of which depends behind the bandsaw blade 3 and can extend downwards lower than the bandsaw blade 3 as viewed in FIG. 2. The upper end of the vertical square rod 41 extends into the interior of the control box 31 and can be raised higher than the top of the control box 31 through an opening 310 formed thereon. Also, the vertical square rod 41 is provided at its upper end with a horizontal elongate plate 45 which is engageable with a tappet or projection 47! of a check valve 47 and a micro switch 49, both of which are fixed within the control box 31.  
  Referring to FIG. 4, the immediately above described check valve 47 is ofthe type which normally allows the hydraulic fluid to flow only in one direction but also allows it to flow in the opposite direction when the tappet or projection 47: is depressed, and it is located in parallel with a flow control valve 51 in a hydraulic passage 53 connecting the hydraulic cylinder 13 with a hydraulic pump 55 which is driven by an electric motor 57 to deliver the hydraulic fluid from a hydraulic tank 59. The flow control valve 51 is used to control the flow of the hydraulic fluid which is drained from the hydraulic cylinder 13 to the hydraulic tank 59 when the bandsaw blade 3 is cutting the material M so that the cutting head 1 holding the bandsaw blade 3 may be lowered at a proper rate according to the cutting requirements of the material M to be cut. A solenoid operated valve 63 having solenoids 65 and 67 is located in the hydrualic passage 53 nearer to the hydraulic pump 55 than the check valve 47 and the flow control valve 51 and it is so designed as to flow the hydraulic fluid towards the hydraulic cylinder 13 when the solenoid 65 is energized to enable the hydraulic fluid to be drained from the cylinder 13 when the solenoid 67 is energized. Also. the micro-switch 49 is electrically connected to the electric motor 57 and the solenoid 65 of the solenoid operated valve 63 through a time limit relay 61 and is so de signed as to de-energize the solenoid 65 and stop the electric motor 57 from operating when it is brought into contact with the upper elongate plate 45 of the vertical elongate rod 41 during the rising ofthe cutting head 1 so as to stop the cutting head l from rising. The numeral 67 designates a relief valve.  
  The operation of the bandsaw machine of the present invention will be described.  
  Firstly. the cutting head 1 is raised and the material M to be cut is placed on the vise 29 and is clamped by the vise jaws 29jr and 29]]. When the solenoid 65 is energized in a conventional manner. the cutting head 1 holding the bandsaw blade 3 starts to lower towards the material M to be cut to enable the bandsaw blade 3 to make the cutting operation. As long as the tappet or projection 47r ofthe check valve 47 is depressed by the upper elongate plate 45 provided on the upper end of the vertical elongate rod 41, the check valve 47 is kept opened. and therefore. the hydraulic fluid from the hydraulic cylinder 13 can pass through the check valve 47 to enable the cutting head 1 and the bandsaw blade 3 to lower quickly.  
  However. once the lower elongate plate 43 fixed to the lower end ofthe vertical elongate rod 41 is brought into contact with the top surface of the material M to be cut. the upper elongate plate 45 is brought out of contact with the tappet or projection 47! of the check valve 47. and the check valve 47 is closed by the action of its spring so that the hydraulic fluid can not flow therethrough from the hydraulic cylinder 13. Accordingly. the hydraulic fluid is drained from the hydraulic cylinder 13 only through the flow control valve 51 at a rate which has been predetermined thereby according to the cutting requirements ofthe material M to be cut so as to enable the bandsaw blade 3 to make an accurate cutting operation. Also. since the lower elongate plate 43 has been so designed as to extend downwards lower than the cutting edge of the bandsaw blade 3 as previously described. the lower elongate plate 43 is brought into contact with the material M to be cut earlier than the bandsaw blade 3. Accordingly. when the bandsaw blade 3 is coming into contact with the material M to be cut. the lowering speed of the cutting head 1 has been dropped and therefore the bandsaw blade 3 can cut into the material M slowly at a reduced rate which has been determined according to the cutting requirements of the material M to be cut. so that the bandsaw blade 3 could not be damaged by the material M.  
  After the lower elongate plate 43 is brought into contact with the top surface of the material M to be cut. it is left thereon without lowering. but the bandsaw blade 3 still continues to be lowered to complete the cycle of the cutting operation.  
  Next. once the cutting head 1 has reached to its bottom limit of the lowering and one cycle of the cutting operation has been completed, the solenoid 65 is energized in a conventional manner as by means of a limit switch to displace the valve 63 rightwards and the electric motor 57 is started also in a conventional manner to drive the hydraulic pump 55. Thus. the hydraulic fluid is delivered from the hydraulic tank 59 into the hydraulic cylinder 13 through the check valve 47 and partially the flow control valve 51 so as to raise the cut ting head 1 together with the bandsaw blade 3.  
  When the bandsaw blade 3 is raised higher than the top surface of the material M to be cut and the bottom end of the lower end of the elongate plate 43, the tappet or projection 47! of the check valve 47 and the micro switch 49 are brought into engagement with the upper elongate plate 45. Accordingly. the check valve 47 is closed and the micro switch 49 works to de energize the solenoid 65 to displace the solenoid oper ated valve 63 to its neutral position and also stop the electric motor 57. so that the cutting head 1 and the bandsaw blade 3 are stopped from going up. Since the bottom end of the lower elongate plate 43 has been so designed as to extend downwards lower than the cutting edge of the bandsaw blade 3. the upper elongate plate 45 is contacted by the tappet or projection 47r of the check valve 47 and the micro switch 49 after the bandsaw blade 3 has been brought up higher than the top surface of the material M to be cut. Also. since the time limit switch 61 is provided in connection with the micro switch 49 to delay the action of the latter. the bandsaw blade 3 is stopped at a position a little higher than the top surface of the material M to be cut. Accordingly. there is some distance between the top sur face ofthe material M to be cut and both of the cutting edge ofthe bandsaw blade 3 and the bottom end of the lower elongate plate 43, and therefore the bandsaw blade 3 is prevented from being damaged by the material M to be cut and also the lower elongate plate 43 is not touched by the material M when the material M is being fed into the cutting positin even if it is very uneven.  
  After the completion ofthe rising ofthe cutting head 1 and the bandsaw blade 3. the material M to be cut is fed into the cutting position of the bandsaw machine. and thereafter the cycles of the cutting operation are repeated.  
  As has been far described. the horizontal bandsaw machine according to the present invention is so de signed that the cutting head 1 holding the bandsaw blade 3 is automatically raised in each of cutting cycles to a position a little higher than the top surface of the material M to be cut according to the height or diameter of the material M and also that the bandsaw balde 3 held by the cutting head 1 is quickly lowered during its idle time when it is idling without making any cutting operation. Accordingly. the idling ofthe bandsaw blade 3 is most minimized and therefore the bandsaw machine in accordance with the present invention is most efficiently used to make the cutting operation.  
  Although the preferred forms of the present invention have been illustrated and described, it should be understood that the device is capable of modification by one skilled in the art without departing from the principles of the invention. Accordingly, the scope fo the invention is to be limited only by the literal interpretation of the claims appended hereto.  
  The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:  
  l. A bandsaw comprising in combination: a base; a head assembly mounted on said base for movement in relation thereto; a cutting blade and associated drive means carried on said head assembly; elevational means for moving said head assembly in relation to said base between a raised inoperative position at which the cutting blade is spaced above a workpiece positioned on said base. and a fully lowered position at the termination of a cut by saidd cutting blade through the workpiece; workpiece contacting means carried on said head assembly for movement in relation thereto in a direction transverse to the cutting direction of said cutting blade, the lower end of said contacting means being adapted to contact a workpiece on said base when said head assembly is lowered by said elevational means, the said lower end being normally at a level beneath that of said cutting blade when out of contact with a workpiece; the control means responsive to movement of said work contacting means relative to said head assembly for controlling the operation of said elevational means to lower said head assembly from the raised inoperative position at a rapid rate until the lower end of said contacting means contacts a workpiece on said base. and thereafter to continue lowering said head assembly at a diminished rate throughout the cutting operation.  
  2. The apparatus as claimed in claim 1 wherein said workpiece contacting means includes an elongated rod mounted on said head assembly for longitudinal movement in relation thereto in a direction transverse to the cutting direction of said cutting blade. said rod having a foot at the lower end thereof positioned to contact a workpiece on said base when the head assembly is lowered by said elevational means.  
  3. The apparatus as claimed in claim 2 wherein prior to contacting said workpiece, the bottom of said foot is beneath the cutting edge of said cutting blade.