Abstract:
A stroke adjusting device for removing eccentric instability in an mechanical rotary system. The stroke adjusting device includes an adjustable rotation balancing weight adjustable about an eccentric bushing positioned on an eccentric shaft. The adjustable rotation balancing weight includes a weight portion adaptable to counteract the instability of the mechanical rotation system, thus minimizing vibration. A hydraulic system enables simple adjustment of the stroke adjusting device.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a slide stroke adjusting device equipped to minimize the vibration in the rotation system of a press machine.  
           [0003]    2. Description of the Related Art  
           [0004]    A conventional device for adjusting the stroke of a slide for a press machine is disclosed in Japanese laid-open Utility Model Publication 7-26099.  
           [0005]    Referring now to FIGS. 4A and 4B, showing a large end of a connecting rod of a press machine (not shown). A small end of connecting rod  11  is connected with a slide of the press machine (not shown).  
           [0006]    A liner  11 A is affixed on the inside of the large end part of connecting rod  11 . An eccentric bushing  2  is slidably and rotatably connected through liner  11 A to connecting rod  11 . An eccentric part  1 A, of an eccentric shaft  1 , connects and joins by an interference fit to eccentric bushing  2 . A groove  5  is provided on one side of eccentric bushing  2 . Groove  5  receives a fixing rod  6  movable in parallel with the axial direction of eccentric shaft  1 . In other words, groove  5  and fixing rod  6  act as a fixing means to fix eccentric bushing  2  relative to connecting rod  11 .  
           [0007]    An internal gear  7  and a hub  3  are positioned on eccentric bushing  2  opposite groove  5 . Internal gear  7  is affixed to eccentric bushing  2 . Hub  3  is movable in an axial direction about eccentric shaft  1 . A teeth space  7 A, is formed on the outer perimeter surface of hub  3 . Teeth space  7 A meshes with inner teeth (not shown) of internal gear  7 . Further, a collar  9  formed on eccentric shaft  1 . Collar  9  acts to restrict the movement of hub  3  away from internal gear  7  and eccentric bushing  2 .  
           [0008]    A coupling body  10  is movable in the axial direction of eccentric shaft  1 , away from hub  3 . Coupling body  10  contacts and pushes the side surface of hub  3 , to mesh the teeth (not shown) formed on the outer perimeter surface of hub  3 , with the inner teeth (not shown) of internal gear  7 .  
           [0009]    An oil passage  4 , through eccentric shaft  1  helps release the interference fit of eccentric part  1 A with eccentric bushing  2 . Pressurized oil, provided through oil passage  4  to an opening (not shown), contacts the inner surface of eccentric bushing  2 . A packing  2 A and a packing  2 B are formed about the outer perimeter surface of eccentric part  1 A where eccentric part  1 A joins eccentric bushing  2 . Under some conventional constructions, packing  2 A and packing  2 B are omitted.  
           [0010]    A packing  3 A and  3 B are positioned on the inner perimeter surfaces of hub  3  where hub  3  contacts the outer perimeters of eccentric part  1 A and eccentric shaft  1 . An oil passage  8 , is formed through eccentric shaft  1  to a surface of eccentric part  1 A opposite hub  3 . Oil passage  8  allows the passage of pressurized oil to urge hub  3  outward away from eccentric part  1 A.  
           [0011]    During stroke adjustment operations, fixing rod  6  is placed in groove  5 , to fix the rotation of eccentric bushing  2 . Pressurized oil next passes through oil passage  8 . Hub  3  moves outward from eccentric part  1 A toward collar  9 . As a result, hub  3  no longer meshes with internal gear  7 . Pressurized oil then passes through oil passage  4 . Eccentric bushing  2  is partially elastically deformed. As a result, the interference fit of eccentric part  1 A is released, and eccentric shaft  1  rotates to adjust the amount of eccentricity relative to eccentric bushing  2 .  
           [0012]    Referring to FIG. 4B, the top-dead center position places an eccentricity P, of eccentric part  1 A with respect to eccentric shaft  1 , in the position shown. The top-dead center position further places an eccentricity Q, of eccentric bushing  2  with respect to eccentric part  1 A, in the position shown. Thus, a maximum stroke length is 2×(P+Q). Further, a minimum stroke length is 2×(Q−P).  
           [0013]    After stroke adjustment, pressurized oil in oil passage  4  and oil passage  8  is released. The shape of eccentric bushing  2  is elastically reformed. The interference fit with eccentric part  1 A re-engages. Coupling body  10  presses against hub  3  and meshes the outer perimeter teeth of hub  3  to the inner teeth of internal gear  7 . Fixing rod  6  is withdrawn from groove  5 , and coupling body  10  is withdrawn from hub  3  and placed on standby in a non-interfering area.  
           [0014]    Using the described stroke adjustment process, the stroke of connecting rod  11  is adjusted. The stroke adjustment conforms to the pitch of the inner teeth of internal gear  7 . Contact provided by meshing internal gear  7  with hub  3 , transfers torque from eccentric part  1  A to eccentric bushing  2 . Torque is then transferred from eccentric bushing  2  to connecting rod  11 .  
           [0015]    Negative results arise when using the above type of conventional stroke adjustment. Under rapid stroke rate, or an increasing stroke rate, the multiple eccentric members rotate rapidly. Thus, internal centrifugal and centripetal forces result in vibration, heat, wear, shorter equipment life span, and increased maintenance costs and operation down-time.  
         OBJECTS AND SUMMARY OF THE INVENTION  
         [0016]    It is an object of the invention to provide a stroke adjustment device for a press machine.  
           [0017]    It is another object of the invention to provide a stroke adjustment device that minimizes the unbalance and vibration resulting from the rotation of conventional stroke adjusting devices.  
           [0018]    It is another object of the invention to provide a stroke adjustment device that is adaptable to vary stroke adjustment positions.  
           [0019]    It is another object of the present invention to provide a stroke adjustment device that both minimizes vibration from a press machine and adjusts simultaneously to stroke adjustments of the press machine.  
           [0020]    It is another object of the present invention to provide a stroke adjustment device that is adaptable to a range of rotary systems requiring stroke adjustment and vibratory dampening.  
           [0021]    Briefly stated, the present invention relates to a stroke adjusting device for removing instability in a mechanical rotation system. The stroke adjusting device includes an adjustable rotation balancing weight attached to an eccentric bushing positioned about an eccentric shaft. The adjustable rotation balancing weight contains a weight portion adaptable to counteract the instability of the eccentric mechanical rotation system thus minimizing vibration. A hydraulic system enables simple adjustment of the stroke adjusting device.  
           [0022]    According to an embodiment of the present invention, there is provided a stroke adjusting rotation balancing device, comprising: an eccentric shaft portion, the eccentric shaft portion receiving a vibration from an external mechanical system, a rotation balancing eccentric bushing affixed about a first part of the eccentric shaft portion, a rotation balancing weight adjustably joined to the eccentric bushing, means for fixing the rotation balancing weight relative to the eccentric bushing, and means for adjusting the rotation balancing weight relative to the eccentric bushing and the eccentric shaft whereby the rotation balancing weight counteracts and dampens the vibration from the external mechanical system.  
           [0023]    According to an embodiment of the present invention, there is provided a stroke adjusting and rotation balancing device, wherein: the means for adjusting includes a hydraulic circuit, and the hydraulic circuit supplying a hydraulic pressure to the eccentric bushing and the rotation balancing weight thereby allowing adjustment of the rotation balancing weight relative to the eccentric bushing to dampen the vibration.  
           [0024]    According to an embodiment of the present invention, there is provided a stroke adjusting and rotation balancing device, wherein: the means for fixing includes a groove, the groove formed in the rotating balancing weight, the means for fixing further includes a fixing rod, the fixing rod extending from a fixed external position, and the fixing rod formed to fit into the groove, whereby the rotation balancing weight is prevented from rotation relative to the eccentric bushing thereby allowing adjustment of the rotation balancing weight relative to the eccentric bushing to dampen the vibration.  
           [0025]    According to an embodiment of the present invention, there is provided a rotation balancing device for a press machine, comprising: a connecting rod having a large end, an eccentric bushing slidably and rotatably provided inside the large end, an eccentric shaft having a first and second side, an eccentric part formed on a first side of the eccentric shaft, the eccentric part adjustably fittable inside the eccentric bushing, the eccentric shaft receiving vibration during operation of the press machine, a rotation balancing eccentric bushing, the rotation balancing eccentric bushing affixed to a second side of the eccentric shaft, a rotation balancing weight, the rotation balancing weight adjustably joined to the rotation balancing eccentric bushing and formed to minimize vibration during operation of the press machine, means for fixing the rotation balancing weight during adjustment, and means for adjusting the rotation balancing weight relative to the rotation balancing eccentric bushing and the eccentric bushing relative to the eccentric part thereby minimizing vibration during operation of the press machine.  
           [0026]    According to an embodiment of the present invention, there is provided a rotation balancing device for a press machine, wherein: the means for fixing includes a fixing rod affixed to an external member, the means for fixing includes a groove formed in the rotation balancing weight, and the fixing rod engagable with the groove during adjustment of the rotation balancing device thereby preventing rotation of the rotation balancing weight relative to the external member.  
           [0027]    According to an embodiment of the present invention, there is provided a rotation balancing device for a press machine, wherein: the means for adjusting includes a first and a second hydraulic circuit, the first hydraulic circuit providing adjustment of the eccentric part relative to the eccentric bushing, the second hydraulic circuit providing adjustment of the rotation balancing eccentric bushing relative to the rotation balancing weight, and the first and second hydraulic circuits being supplied simultaneously whereby adjustment of the eccentric part and the rotation balancing eccentric bushing occur simultaneously.  
           [0028]    According to an embodiment of the present invention there is provided a stroke adjusting device in a rotary system including a connecting rod, an eccentric bushing slidably and rotatably provided inside a first end of the connecting rod, and an eccentric shaft in which an eccentric part is joined to the eccentric bushing by an adjustable fit, the stroke adjusting device comprising: a rotation balancing eccentric bushing affixed to the eccentric shaft, a rotation balancing weight fitted to the rotation balancing eccentric bushing, the rotation balancing weight adjustable relative to the rotation balancing eccentric bushing, means for fixing the rotation balancing weight during adjustment, and a hydraulic circuit enabling the adjustment of the rotation balancing weight relative to the rotation balancing eccentric bushing whereby vibration is minimized in the rotary system.  
           [0029]    According to an embodiment of the present invention there is provided a stroke adjusting device, wherein: the hydraulic circuit enables simultaneous adjustment of the eccentric part relative to the eccentric bushing and the rotation balancing weight relative to the rotation balancing eccentric bushing.  
           [0030]    According to an embodiment of the present invention there is provided a stroke adjusting device, wherein: the means for fixing includes a groove portion formed on the rotation balancing weight, and a fixing rod member affixed to an external member and insertable into the groove portion to restrain rotation of the rotation balancing weight relative the eccentric shaft.  
           [0031]    Furthermore, when conducting the operation of stroke adjustment, the interference fit of the eccentric part and the eccentric bushing is released. In the present embodiment, in addition to the interference fit of the eccentric part and the eccentric bushing, the interference fit of the rotation balancing eccentric bushing and the rotation balancing weight is release-able and adjustable. Thus, when the eccentric shaft is rotated in order to adjust the stroke, together with the rotation of the eccentric part, the rotation balancing eccentric bushing is also rotated, and the eccentricity of the rotation balancing weight changes and vibration is damped.  
           [0032]    As a result, the eccentricity of the rotation balancing weight can be changed according to the change in eccentricity of the eccentric bushing. Therefore, regardless of the various stroke amounts, the vibration or unbalance in the rotation system may always be minimized.  
           [0033]    In the invention according to the present embodiment, the oil pressure circuit that releases the interference fit of the eccentric bushing and the eccentric part and the oil pressure circuit that releases the interference fit of the rotation balancing eccentric bushing and the rotation balancing weight operate in common. As a result, adjustment is simplified and the time consumed in the adjustment procedure is minimized thereby minimizing costs.  
           [0034]    The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements. 
       
    
    
     BRIEF DESCRIPTION OF THE FIGS.  
       [0035]    [0035]FIG. 1 is a side view of an embodiment of the present invention.  
         [0036]    [0036]FIG. 2 is a cross-section along line A-A of FIG. 1.  
         [0037]    [0037]FIG. 3 is a descriptive figure of the eccentricity of the present invention.  
         [0038]    [0038]FIG. 4(A) is a front view of a vertical cross-section of a stroke adjustment device of a conventional embodiment.  
         [0039]    [0039]FIG. 4(B) is a side view of the essential parts of the stroke adjustment device of a conventional embodiment.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0040]    Referring now to FIGS. 1 and 2, showing a stroke adjusting device incorporating the present invention at a position of top-dead-center and maximum stroke amount. Elements  1  through  3  and  5  through  11 A perform the same functions as corresponding elements in FIGS.  4 (A) and  4 (B). Further description of these elements is omitted.  
         [0041]    A rotation balancing eccentric bushing  21  is affixed to eccentric shaft  1 . Eccentric shaft  1  extends axially from connecting rod  11  to a shaft cover  23 . A key  22 , stops rotation balancing eccentric bushing  21  from rotating relative to eccentric shaft  1 . Shaft cover  23  fixes rotation balancing eccentric bushing  21  to eccentric shaft  1  to prevent unplanned removal. It is to be understood that the eccentricity of rotation balancing eccentric bushing  21  is opposite the eccentricity of eccentric bushing  2 .  
         [0042]    A rotation balancing weight  25  adjoins rotation balancing eccentric bushing  21  through an interference fit. It is to be understood that an interference fit is a fit wherein the forces of friction primarily, but not completely, affix one part to another. Rotation balancing weigh  25  includes weight part  25 A. Weight part  25 A extends from rotation balancing weigh  25  away from eccentric shaft  1 . A pair of stopping plates  24  contact balancing weight  25 . Stopping plates  24  are on the shaft cover  23  side surface of rotation balancing eccentric bushing  21 . Stopping plates  24  prevent unplanned removal of rotation balancing weight  25  from eccentric rotation balancing eccentric bushing  21 .  
         [0043]    A first packing  28 A and a second packing  28 B are positioned about the outer perimeter surface of rotation balancing eccentric bushing  21 . First packing  28 A and second packing  28 B extend from rotation balancing eccentric bushing  21  to rotation balancing weight  25 .  
         [0044]    An oil passage  4 B, through rotation balancing eccentric bushing  21 , receives a pressurized fluid, typically oil. Oil passage  4 B transmits hydraulic pressure to the interface between rotation balancing weight  25  and rotation balancing eccentric bushing  21 . Oil passage  4 B includes at least one opening, and as shown includes  2  openings, between packing  28 A and  28 B. During stroke adjustment, oil passage  4 B transmits pressure to rotation balancing eccentric bushing  21 . Rotation balancing eccentric bushing  21  elastically deforms and releases the interference fit with rotation balancing weight  25 .  
         [0045]    An oil passage  4 A, through rotation balancing eccentric bushing  21 , receives a pressurized fluid, also typically oil. Oil passage  4 A transmits hydraulic pressure to the interface between eccentric bushing  2  and eccentric part  1 A. During stroke adjustment, oil passage  4 A transmits pressure to eccentric bushing  2 . Rotation balancing bushing  2  elastically deforms and released the interference fit with eccentric part  1 A.  
         [0046]    It is to be understood that packing  28 A and packing  28 B may be omitted and other means provided to minimize the interference fit. It is to be further understood that oil passage  4 A, and oil passage  4 B are supplied from the same pressure circuit in this embodiment, but that additional or alternative hydraulic systems may be provided without changing the nature or scope of the invention.  
         [0047]    A fixing rod  27  moves parallel to eccentric shaft  1 , opposite rotation balancing weight  25 . A groove  26  on rotation balancing weight  25  opposite fixing rod  27  receives and slidably engages fixing rod  27 . Both fixing rod  27  and groove  26  engage to restrain the rotation of rotation balancing weight  25  relative to eccentric shaft  1  during stroke adjustment. As a result, fixing rod  27  and groove  26  serve as a means for fixing the rotation balancing weight  25  relative to eccentric shaft  1  or rotation balancing eccentric bushing  21 . It is to be understood that other means for fixing the rotation of rotation balancing weight  25  may be provided according to the convenience of the manufacturer or desire of a consumer or designer.  
         [0048]    Additionally referring now to FIG. 3 showing a distance e1, as the amount of eccentricity of eccentric part  1 A. A second distance e2, is the amount of eccentricity of rotation balancing eccentric bushing  21 . A first position e1′, is the position of the center of gravity of eccentric bushing  2  and connecting rod  11 . First position e1′ is relative to the rotational center of eccentric bushing  2  and connecting rod  11 . A second position e2′, is the position of the center of gravity of weight part  25 A, relative to the rotational center of weight part  25 A. It is to be understood, that the center of gravity as used above is also the center of mas of the object described.  
         [0049]    During adjustment, fixing rod  27  is inserted into groove  26  and prevents the rotation of rotation balancing weight  25 . Pressurized oil, supplied through oil passage  4  pressurizes oil passage  4 A and oil passage  4 B. The pressurized oil releases the interference fit of eccentric part  1 A and eccentric bushing  2 . Eccentric part  1 A is then movable relative to eccentric bushing  2 . Further, the pressurized oil, sealed by packing  28 A and packing  28 B, elastically deforms rotation balancing eccentric bushing  21 . The pressurized oil releases the interference fit between rotation balancing eccentric bushing  21  and rotation balancing weight  25 . As a result, rotation balancing eccentric bushing  21  and rotation balancing weight  25  are movable relative to each other.  
         [0050]    During adjustment of the slide stroke adjustment device, eccentric shaft  1  rotates relative to eccentric bushing  2 . As eccentric shaft  1  rotates, rotation balancing eccentric bushing  21  also rotates relative to rotation balancing weight  25 . Thus, in conjunction with a change in the sum of the eccentricities, of eccentric bushing  2  and eccentric part  1 A, the eccentricity of rotation balancing weight  25  also changes. As a result, the eccentric vibrational forces are substantially reduced.  
         [0051]    The rotational force, developed by eccentric bushing  2  and connecting rod  11  is described below. Further, the rotational force developed by rotation balancing weight  25 , both before and after the rotation of eccentric shaft  1  is described below.  
         [0052]    A distance R1, is the distance from the center of fixing rod  6  to the center of eccentric shaft  1 . A distance R2, is the distance from the center of fixing rod  27  to the center of eccentric shaft  1 . A third position e3, is the position of the center of gravity of eccentric bushing  2  and connecting rod  11  after rotating eccentric shaft  1  an angle theta (θ) from the maximum stroke, as will be explained. Angle theta is abbreviated as θ in FIG. 3. A fourth position e4, is the position of the center of gravity of weight part  25 A after rotating eccentric shaft  1  angle theta (θ) from the maximum stroke, as will be explained. Further, a first weight w1 (not shown), is the total weight of eccentric bushing  2  and connecting rod  11 . A second weight w2 (not shown), is the weight of weight part  25 A. It is to be understood, that the term weight is interchangeable with the term mass.  
         [0053]    As a result, a distance L1, from the center of eccentric part  1 A to the center of fixing rod  6 , may be calculated by the following formula:  
           L 1=( e 1 2   +R 1 2 +−2× e 1× R 1×cos θ) ½   (I)  
         [0054]    Additionally, an angle theta 1 (abbreviated as θ1 in FIG. 3), is formed between distance L1 and the direction of eccentricity of eccentric part  1 A. Angle theta 1 (θ1) may be calculated by the following formula:  
           Theta  1(θ1)=cos −1 (( e 1 2   +L 1 2   −R 1 2 )/(2 ×e 1 ×L 1))  (II)  
         [0055]    As a further result, the position of the center of gravity e 3  may be shown by the following formula:  
           e 3( e 1 2   +e 1′ 2 −2× e 1× e 1′×cos θ) ½   (III)  
         [0056]    Thus, a first centrifugal force F1 (not shown), due to the rotation of eccentric part  1 A, is the following formula. In formula IV, a variable G, represents gravitational acceleration, a variable N, represents the strokes per minute of the press machine device, and a constant pi(π) represents the mathematical constant.  
           F 1 =w 1 /G×e 3×(2 ×pi×N/ 60) 2   (IV)  
         [0057]    Further a distance L2, from the center of rotation balancing eccentric bushing  21  to fixing rod  27 , is determinable from the following formula:  
           L 2=( e 2 2   +R 2 2 −2 ×e 2 ×R 2×cos θ) ½   (V)  
         [0058]    Additionally, an angle theta 2 (abbreviated as θ2 in FIG. 3), is formed between distance L2 and the direction of eccentricity of rotation balancing eccentric bushing  21 , is determinable from the following formula:  
           Theta  2(θ2)=cos −1 (( e 2 2   +L 2 2 −R2 2 )/(2× e 2 ×L 2))  (VI)  
         [0059]    As a further result, the position of center of gravity e4 is determinable from the following formula:  
           e 4( e 2 2   +e 2′ 2 −2 ×e 2 ×e 2′×cos θ) ½   (VII)  
         [0060]    Furthermore, a displacement angle gamma (abbreviated as γ in FIG. 3), of the position of center of gravity e3 and position of center of gravity e4, is determinable from the following formula:  
         gamma(γ)=cos −1 (( e 1 2   +e 3 2   −e 1′ 2 )/(2 ×e 1 ×e 3))−cos −1 (( e 2 2   +e 4 2   −e 2′ 2 )/(2× e 2× e 4))  (VIII)  
         [0061]    Thus, a second centrifugal force F2 (not shown), due to the rotation balancing weight  25  and directly opposes first centrifugal force F1, is determinable as follows:  
           F 2= w 2 /G×e 4×(2× pi×N/ 60) 2 ×cos(γ)  (IX)  
         [0062]    Where e1=e2, w1=w2, e1′=e2′, and R1=R2, from each of the above formulas; then e3=e4, displacement angle gamma(γ)=0, and the relationship between first and second centrifugal forces F1, F2 becomes F1=F2.  
         [0063]    Thus, where the above-described calculations are applied to a stroke adjusting device or a vibration dampening device according to the present invention, even where the eccentricity of eccentric bushing  2  changes due to stroke adjustment, the eccentric vibration about eccentric shaft  1  may be substantially removed. As a result, device wear, mechanical fatigue, mechanical failure, noise and thermal accumulation are minimized and a comfortable and efficient work environment may be maximized. As a further result, device life is extended while allowing operation of a high precision press machine.  
         [0064]    It is to be understood, that while the present invention is applied to a stroke adjustment device for a press machine, the instant invention is adaptable for use in multiple other situations requiring the minimization of rotational or eccentric vibration.  
         [0065]    It is to be additionally understood that the weight and design of the rotation balancing weight  25  and the rotation balancing eccentric bushing  21  are provided at positions where the vibration or unbalance of the rotation system may be removed.  
         [0066]    It is to be additionally understood that the above-described stroke adjusting device for a press machine may be alternatively described as a rotation balancing device.  
         [0067]    Although only a single or few exemplary embodiments of this invention has been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the above exemplary embodiment(s) without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Thus although a nail and screw may not be structural equivalents, in that a nail relies entirely on friction between a wooden part and a cylindrical surface whereas a screw&#39;s helical surface positively engages the wooden part, in the environment of fastening parts, a nail and a screw may be equivalent structures.  
         [0068]    Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be further understood that the invention is not limited to these precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.