Abstract:
A slide guide device for a press guides a slide in a cycle. The slide guide device eliminates eccentric force misalignment and prevents eccentric contact between the slide and a gib. The slide includes at least a first spherical shoe having at least a first guide surface. The gib includes at least a first sliding surface opposite the first guide surface. During operation, the spherical shoe rotates relative to the slide to provide automatic planar alignment between the first guide surface and the sliding surface. A wedge supports the gib to allow rapid and easy alignment with the slide.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a slide guide device for a press. More specifically, the present invention relates to a slide guide device that guides a slide with high precession during pressing operations.  
           [0003]    2. Description of the Related Art  
           [0004]    Conventionally, a press includes a slide. A copper alloy liner serves as a slide surface. The press includes an iron gib disposed on a frame opposite the slide surface. During operation, the liner and the gib slide against each other to guide the slide along the frame.  
           [0005]    Clearance between the liner and its facing gib is approximately 5/100 mm. Typically, a lubricating oil lubricates the sliding surfaces. The lubricating oil forms an oil membrane between the liner and the gib to minimize friction and wear.  
           [0006]    Unfortunately, eccentric forces frequently occur in the press. These eccentric forces force the liner and gib to form ‘line contacts.’ Line contacts occur when failure of the lubricating oil membrane permits direct sliding contact to occur. Direct contact wears and scorches the sliding surfaces and increases the mechanical resistance to be overcome by the press motor. If not remedied, the line contacts cause motor failure and costly equipment damage.  
           [0007]    Additionally, the clearance required to maintain an oil membrane is detrimental to high-precision goals. In particular with large high-precision presses with eccentric loads, the large slides maximize pressure with resulting detrimental line contacts. Conventionally, this detrimental effect is partially ameliorated through use of “two-point” and “four-point” press designs.  
           [0008]    “Two-point” and “four-point” presses require costly precision construction. Production of precision parts is difficult, costly, and time consuming. Ultimately, no matter how precise the construction, eccentric loads may still cause line contacts between the liner and the gib.  
           [0009]    The applicant&#39;s previously filed Japanese patent application number 2000-193782 partially overcomes this difficulty using a spherical surface block and a gib sliding against each other along a liner that has a V-shaped sliding surface. Unfortunately, aligning the V shape of the spherical surface block and the gib is difficult. Despite this design, ultimately during high loads the V-shaped surface of the spherical surface block spreads, causing damaging contact, costly repair and downtime.  
         OBJECTS AND SUMMARY OF THE INVENTION  
         [0010]    An object of the present invention is to provide a slide guide device for a press that overcomes the problems and difficulties described above.  
           [0011]    It is another object of the present invention to provide a slide guide device which improves uniform contact along each sliding surface.  
           [0012]    It is another object of the present invention to provide a slide guide device which improves pressing precision and accuracy.  
           [0013]    It is another object of the present invention to provide a slide guide device which compensates for eccentric forces during pressing and eliminates eccentric contact between each sliding surface.  
           [0014]    It is another object of the present invention to provide a slide guide device that employs a gib structure using a rotatable element to maintain uniform contact between each sliding surface.  
           [0015]    It is another object of the present invention to provide a slide guide device that is easily adjustable to set and fix an optimum gap between sliding surfaces.  
           [0016]    It is another object of the present invention to provide a slide guide device which compensates for both lateral and eccentric loads during pressing operations and allows for simple assembly.  
           [0017]    It is another object of the present invention to provide a slide guide device which has the foregoing features and capabilities.  
           [0018]    The present invention relates to a slide guide device for a press which guides a slide in a cycle. The slide guide device eliminates misalignment caused by eccentric forces and prevents eccentric contact between the slide and a gib. The slide includes at least a first spherical shoe having at least a first guide surface. The gib includes at least a first sliding surface opposite the first guide surface. During operation, the spherical shoe rotates relative to the slide to ensure close alignment between the first guide surface and the sliding surface. A wedge supporting the gib allows rapid and easy alignment with the slide.  
           [0019]    According to an embodiment of the present invention there is provided a slide guide device for a press machine, comprising: a slide, at least a first cavity on a first side of the slide, at least a first interface element, first means for rotatably retaining the first interface element in the first cavity, at least a first contact surface on the first interface element, at least a first gib opposite the slide and the first cavity, at least a first slide surface on the first gib, and first means for rotatably aligning the first contact surface with the first slide surface guiding and aligning the slide with the first gib during a cycle, thereby preventing an eccentric slide misalignment during the cycle and increasing press precision.  
           [0020]    According to another embodiment of the present invention there is provided a slide guide device for a press machine, further comprising: at least a second cavity on a second side the slide, at least a second interface element, second means for rotatably retaining the second interface element in the second cavity, at least a second contact surface on the second interface element, at least a second gib opposite the slide and the second cavity, at least a second slide surface on the second gib, and second means for rotatably aligning the second contact surface with the second slide surface guiding and aligning the slide with the second gib during the cycle, thereby preventing the eccentric slide misalignment and increasing the press precision.  
           [0021]    According to another embodiment of the present invention there is provided a slide guide device for a press machine, further comprising: at least a first clearance between the first contact surface and the first slide surface, at least a second clearance between the second contact surface and the second slide surface, and means for slidably adjusting and fixing the first and the second clearance and retaining each respective the first and the second clearance at a selected optimum clearance thereby maintaining alignment of the slide easily guiding the slide in the cycle.  
           [0022]    According to another embodiment of the present invention there is provided a slide guide device for a press machine, wherein: the means for slidably adjusting and fixing includes the first gib, the first gib has at least a first wedge shape, at least a first support element in the means for slidably adjusting and fixing, the first support element between the first gib and a frame of the press machine, the first support element has a second wedge shape, the second wedge shape complementary to the first wedge shape, the first support element adjustable along the frame and fixable relative to the first gib and the frame, and the means for slidably adjusting and fixing effective to slide the first support element relative to the first gib and the frame, create the optimum clearance, and fix the first and the second clearance at the optimum clearance, whereby the slide easily maintains the optimum clearance during the cycle.  
           [0023]    According to another embodiment of the present invention there is provided a slide guide device for a press machine, wherein: the at least first contact surface and the at least first slide surface are flat, the at least second contact surface and the at least second slide surface are flat, the first slide surface at a first angle to an axis of the slide, the axis extending linearly from the first gib, through the slide, to the second gib, and the second slide surface at a second angle to the axis of the slide.  
           [0024]    According to another embodiment of the present invention there is provided a slide guide device for a press machine, wherein: the first slide surface is perpendicular to the axis, and the second slide surface is perpendicular to the axis.  
           [0025]    According to another embodiment of the present invention there is provided a slide guide device for a press machine, further comprising: at least a third cavity on the first side of the slide, at least a third interface element, the first means for rotatably retaining also rotatably retaining the third interface element in the third cavity, at least a third contact surface on the third interface element, the first gib opposite the first and the third cavity, at least a third slide surface on the first gib, and the first means for rotatably aligning also rotatably aligning the third contact surface with the third slide surface during the cycle, thereby preventing the eccentric slide misalignment and a lateral slide misalignment during the cycle.  
           [0026]    According to another embodiment of the present invention there is provided a slide guide device for a press machine, further comprising: at least a fourth cavity on the second side of the slide, at least a fourth interface element, the second means for rotatably retaining also rotatably retaining the fourth interface element in the fourth cavity, at least a fourth contact surface on the fourth interface element, the second gib opposite the second and the third cavity, at least a fourth slide surface on the second gib, and the second means for rotatably aligning also rotatably aligning the fourth contact surface with the fourth slide surface during the cycle, thereby preventing the eccentric slide misalignment and the lateral slide misalignment during the cycle.  
           [0027]    According to another embodiment of the present invention there is provided a slide guide device for a press machine, further comprising: at least a third clearance between the third contact surface and the third slide surface, at least a fourth clearance between the fourth contact surface and the fourth slide surface, and means for slidably adjusting and fixing including means for slidably adjusting and fixing the third and the fourth clearance and retaining each respective the third and the fourth clearance at the selected optimum clearance thereby maintaining alignment of the slide in the cycle.  
           [0028]    According to another embodiment of the present invention there is provided a slide guide device for a press machine, wherein: the at least third contact surface and the at least third slide surface are flat, the at least fourth contact surface and the at least fourth slide surface are flat, the first slide surface and the third slide surface at a third angle to the axis of the slide, and the second slide surface and the fourth slide surface at a fourth angle to the axis of the slide.  
           [0029]    According to another embodiment of the present invention there is provided a slide guide device for a press machine, wherein: the third angle is a first acute angle, and the fourth angle is a second acute angle.  
           [0030]    According to another embodiment of the present invention there is provided a slide guide device for a press machine, wherein: the third angle is a first obtuse angle, and the fourth angle is a second obtuse angle.  
           [0031]    According to another embodiment of the present invention there is provided a slide guide device for a press machine, wherein: the first contact surface is at a first 120-degree angle to the third contact surface, and the second contact surface is at a second 120-degree angle to the fourth contact surface.  
           [0032]    According to another embodiment of the present invention there is provided a slide guide device for a press machine, wherein: the first and the second 120-degree angles project away from the slide along the axis.  
           [0033]    According to another embodiment of the present invention there is provided a slide guide device for a press machine, wherein: the first and the second 120-degree angles project toward the slide along the axis.  
           [0034]    According to another embodiment of the present invention there is provided a slide guide device for a press machine, further comprising: at least a fifth contact surface on the first interface element, the first contact surface at a third obtuse angle to the fifth contact surface, at least a sixth contact surface on the second interface element, the second contact surface at a fourth obtuse angle to the sixth contact surface, a fifth slide surface on the first gib opposite the fifth contact surface, a sixth slide surface on the second gib opposite the sixth contact surface, the first means for rotatably aligning also including means for simultaneously and rotatably aligning the fifth contact surface with the fifth slide surface, and the second means for rotatably aligning also including means for simultaneously and rotatably aligning the sixth contact surface with the sixth slide surface.  
           [0035]    According to another embodiment of the present invention there is provided a slide guide device for a press machine, wherein: the third obtuse angle is 120 degrees, and the fourth obtuse angle is 120 degrees.  
           [0036]    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 DRAWINGS  
       [0037]    [0037]FIG. 1 is a front view of a press.  
         [0038]    [0038]FIG. 2 is a horizontal cross-section of a gib in a first embodiment of the present invention.  
         [0039]    [0039]FIG. 3 is a horizontal cross-section of a gib in a second embodiment.  
         [0040]    [0040]FIG. 4 is a detail drawing of a gib section in the second embodiment.  
         [0041]    [0041]FIG. 5 is a horizontal cross-section of a gib in a third embodiment.  
         [0042]    [0042]FIG. 6 is a detail drawing of a gib section in a third embodiment.  
         [0043]    [0043]FIG. 7 is a horizontal cross-section of a gib in a fourth embodiment.  
         [0044]    [0044]FIG. 8 is a detail drawing of a gib section in a fourth embodiment.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0045]    Referring now to FIGS. 1 and 2, a press  50  includes a frame  1 . Frame  1  supports a bed  51 . Frame  1  includes a left side frame and a right side frame (both not numbered). A pair of stays  19  join the left side frame and the right side frame. Stays  19  provide additional stability to press  50  during operation.  
         [0046]    A bolster  3  is disposed on bed  51  opposite slide  2   a . A slide  2   a  is slidably operable along frame  1  relative to bolster  3  and to bed  51 . Slide  2   a  is connected to a connecting rod  4  and a crank shaft (not shown). Connecting rod  4  and the crank shaft form a crank mechanism for operating slide  2   a . During operation, the crank mechanism reciprocates slide  2   a  relative to bolster  3 .  
         [0047]    Stays  19  join frame  1  at a point roughly midway in a range of vertical motion of slide  2   a . During pressing, stays  19  prevent deformation and torsion of frame  1 .  
         [0048]    A pair of gibs  5   a ,  6   a  on frame  1  are located on respective left and right side frame members opposite slide  2   a . Spherical shoes  7 ,  8 ,  9 ,  10  are disposed on slide  2   a , as will be explained. Spherical shoes  7 ,  8  and gib  5   a  are on a first side of slide  2   a . Spherical shoes  9 ,  10  and gib  6   a  are on the second side of slide  2   a . During operation, gibs  5   a ,  6   a  engage respective spherical shoes  7 ,  8 ,  9 ,  10  to guide slide  2   a  upward and downward on frame  1 .  
         [0049]    A pair of gib holders  13 ,  14  on frame  1  secure gib  5   a  relative to slide  2   a , as will be explained.  
         [0050]    An engagement section  13   a  is on gib holder  13 . An engagement section  14   a  is on gib holder  14 . Engagement sections  13   a ,  14   a  engage respective grooves (shown but not numbered) on frame  1 . Engagement sections  13   a ,  14   a  align respective gib holders  13 ,  14  to frame  1 . Bolts (not shown) secure gib holders  13 ,  14  to frame  1 .  
         [0051]    A hollow screw  15 ′ is screwed into gib holder  13 . A hollow screw  15 ″ is screwed into gib holder  14 . A bolt  16 ′ extends through hollow screw  15 ′. A bolt  16 ″ extends through hollow screw  15 ″. Bolts  16 ′,  16 ″ secure hollow screws  15 ′,  15 ″ to respective gib holders  13 ,  14 .  
         [0052]    An end of bolt  16 ″ extends through hollow screw  15 ″ in gib holder  14 . A wedge  12  threadably engages the end of bolt  16 ″. Bolt  16 ″ slidably retains wedge  12  relative to gib holders  13 , 14 . During assembly or adjustment, hollow screw  15 ″ and bolt  16 ″ threadably control and position wedge  12  relative to gib holder  14 .  
         [0053]    An end of bolt  16 ′ extends through hollow screw  15 ′ in gib holder  13 . Gib  5   a  threadably engages the end of bolt  16 ′. Bolt  16 ′ slidably retains gib  5   a  relative to gibe holder  13 . During assembly or adjustment, hollow screw  15 ′ and bolt  16 ′ threadably control and position gib  5   a  relative to gib holder  13 .  
         [0054]    Wedge  12 , between gib  5  a and frame  1 , has a tapered shape that matches a tapered shape of gib  5   a . Wedge  12  supports gib  5   a . Wedge  12  and gib  5   a  slidably engage and allow easy adjustment of gib  5   a  relative to slide  2   a . After assembly and adjustment, bolts  17  secure wedge  12  and gib  5   a  to frame  1 .  
         [0055]    A liner  11  is secured with at least one screw (not shown) on an outer surface of gib  5   a  between gib  5   a  and slide  2   a . Liner  11  is typically a Teflon-based impregnated porous bi-metal, but may be any convenient wear resistant and slippery material. In this embodiment, liner  11  is plate-shaped affixed vertically along gib  5   a.    
         [0056]    At least one spherical cavity  18  is on slide  2   a  opposite gib  5   a . Spherical cavity  18  has a concave hemispheric shape. Spherical shoe  7  is positioned in spherical cavity  18 . Spherical shoe  7  has a convex hemispheric section which matches the concave hemispheric shape of spherical cavity  18 .  
         [0057]    Spherical shoe  7  has a flat section opposite the hemispheric section. During assembly, the flat section of spherical shoe  7  contacts liner  11 . During operation, the flat section of spherical shoe  7  slidably contacts liner  11 . During operation, when eccentric forces occur, the hemispheric section of spherical shoe  7  adjusts relative to spherical cavity  18  to maintain the flat section parallel to liner  11  and gib  5   a , thereby eliminating line contacts.  
         [0058]    Gib  6   a  is fixed relative to frame  1 . In combination, gib  5   a  and gib  6   a  increase the operational precision of press  50  and guide slide  2   a  during a slide cycle.  
         [0059]    An engagement section  14   a ′ on gib  6   a  fits into at least one groove formed (shown but not numbered) in frame  1 . During assembly, at least one additional bolt  17  secures gib  6   a  to frame  1 .  
         [0060]    Gibs  5   a ,  6   a  each include two comer guide surfaces (shown but not numbered) opposite slide  2   a . The guide surfaces on gib  5   a  are opposite two respective comers of slide  2   a . The guide surfaces on gib  6   a  are opposite the respective other two comers of slide  2   a . During operation, the four comers of slide  2   a  operate parallel to their respective comer guide surface of gibs  5   a ,  6   a.    
         [0061]    A set of shoes  23  is affixed to slide  2   a  on each comer of slide  2   a . Shoes  23  are opposite respective comer guide surface on gibs  5   a ,  6   a . In the first embodiment of the present invention, slide  2   a  is easily and guidably restrained along a left/right axis by spherical shoes  7 ,  8 ,  9 , and  10 , and along a forward/back axis by shoes  23 . As a result, precision operation is easily achieved without increased operational costs or the need for precision machining.  
         [0062]    During assembly, bolt  17  secures gib  6   a  to frame  1 . Spherical shoes  7 ,  8 ,  9 , and  10  are installed within their respective cavities  18  on opposite sides of slide  2   a . The now-assembled slide  2   a  is placed in frame  1  along gib  6   a . Wedge  12  and gib  5   a  are assembled opposite slide  2 . Wedge  12  and gib  5   a  are positioned and adjusted using respective hollow screws  15 ′,  15 ″ and bolts  16 ′,  16 ″ while maintaining even contact between liners  11  and spherical shoes  7 ,  8 ,  9 , and  10 . Finally, after positioning and adjusting, additional bolts  17  secure wedge  12  and gib  5   a  to frame  1 .  
         [0063]    Referring now to FIGS. 3 and 4 a second alternative embodiment of the present invention includes a gib holder  14 ′ and gib holders  13 ,  14 . Engagement section  13   a  is located on gib holder  13 . Engagement section  14   a  is located on gib holder  14 . An engagement section  14   a ″ is located on gib holder  14 ′.  
         [0064]    Engagement sections  13   a ,  14   a  engage groves (shown but not numbered) on one side of frame  1 . Engagement sections  13   a ,  14   a  align respective gib holders  13 ,  14  to frame  1 . Gib holders  13 ,  14  align and support a gib  5   b , relative to frame  
         [0065]    Engagement section  14   a ″ aligns gib holder  14 ′ with frame  1 . Gib holder  14 ′ aligns and supports a gib  6   b  relative to frame  1 . During operation, gibs  5   b ,  6   b  precisely and reliably guide slide  2   b  along frame  1 , as will be explained.  
         [0066]    Engagement section  14   a ″ engages an engagement groove (shown but not numbered) on frame  1  opposite engagement sections  13   a ,  14   a . A hollow screw  15 ″′ threadably engages gib holder  14 ′. A bolt  16 ″′ is inserted into hollow screw  15 ″′. An end of bolt  16 ″′ threadably engages gib  6   b  to allow adjustment of gib  6   b  relative to frame  1 . After adjustment, at least one bolt  17  fixes gib  6   b  to frame  1 .  
         [0067]    An abutting section  6   a ′ on frame  1  opposite gib  6   b  resists pressure from bolt  16 ″′ and supports gib  6   b  during assembly and operation.  
         [0068]    In this embodiment, hollow screw  15 ′ is screwed into gib holder  13 . Hollow screw  15 ″ is screwed into gib holder  14 . Bolt  16 ′ is inserted into hollow screw  15 ′. Bolt  16 ″ is inserted into hollow screw  15 ″.  
         [0069]    An end of bolt  16 ′ screws into wedge  12  to join gib holder  13  to wedge  12 . During assembly, an end of hollow screw  15 ′ helps to position wedge  12 . Bolt  16 ′ secures hollow screw  15 ′ to gib holder  13 . In combination, hollow screw  15 ′ and bolt  16 ′ secure wedge  12  relative to gib holder  13 .  
         [0070]    An end of bolt  16 ″ is screwed into gib  5   b  to join gib holder  14  to gib  5   b . During assembly, an end of hollow screw  15 ″ positions gib  5   b . Bolt  16 ″ secures hollow screw  15 ″ to gib  5   b . In combination, hollow screw  15 ″ and bolt  16 ″ secure gib  5   b  relative to gib holder  14 , wedge  12  and slide  2   b . Once wedge  12  and gib  5   b  are positioned, at least one bolt  17  secures gib  5   b  and wedge  12  to frame  1 .  
         [0071]    A first pair of liners,  11 ,  11  are secured to gib  5   b  opposite slide  2   b . A second pair of liners (not shown) is secured to gib  6   b  in a similar manner. Liners  11 ,  11  have plate-like shapes and are vertically affixed along gibs  5   b ,  6   b.    
         [0072]    Each gib  5   b ,  6   b  has two contact surfaces extending parallel along slide  2   b . Liners  11  are located on the respective contact surface along gib  5   b  and  6   b . Slide  2   b  has contact surfaces corresponding to the contact surfaces on gibs  5   b ,  6   b . The contact surfaces on gibs  5   b ,  6   b  and slide  2   b  slide parallel to each other to allow easy and precise movement of slide  2   b.    
         [0073]    In this embodiment, pairs of spherical shoes  7 ,  7  and  9 ,  9  rotatably fit within corresponding spherical cavities  18  on slide  2   b . The flat sections of spherical shoes  7 ,  7  contact liners  11  on gib  5   b  and slide freely. The flat sections of spherical shoes  9 ,  9  similarly contact liners  11  on gib  6   b  and slides freely. The spherical surface of spherical shoes  7 ,  7 , and  9 ,  9  rotate within cavities  18  to allow the entire surface of their respective flat sections to remain parallel to their respective liners  11 .  
         [0074]    During assembly, the pairs of spherical shoes  7 ,  8 ,  9 ,  10  are fitted into corresponding cavities  18  on slide  2   b . Gib  6   b  is adjusted and fixed to frame  1 . Slide  2  is placed in frame  1 . Wedge  12  and gib  5   b  are assembled, positioned, and adjusted using hollow screws  15 ′,  15 ″ and bolts  16 ′,  16 ″ while observing the contact between liners  11  and respective spherical shoes  7 ,  8 ,  9 , and  10 . After adjustment, bolts  17  secure wedge  12  and gib  5   b  to frame  1 .  
         [0075]    The contact surfaces on gibs  5   b ,  6   b  correspond to the surfaces of each pair of liners  11 ,  11 . An angle alpha (α) is an angle between the contact surface (and of the liners  11 ). Angle alpha (α) is selected based upon the state of eccentric loads during pressing operations.  
         [0076]    During operation, pressure (force) from slide  2   b  passes through respective spherical shoes  7 ,  8 ,  9 , and  10  and is transferred to the contact surface of liners  11 .  
         [0077]    The forces acting on each contact surface can be analyzed, based on the slope of the contact surface. The forces can be broken down into a force providing restriction along a left-right axis of slide  2   b  and a force providing restriction along a forward-backward axis of slide  2   b . Thus, slide  2   b  is restricted along the left-right axis and the forward-backward axis by gibs Sb,  6   b.    
         [0078]    In the present embodiment, angle alpha (α) is approximately 120 deg. In this embodiment, the eccentric load along the left-right axis of slide  2   b  is larger than the eccentric load along the front-back axis. In other words, the projected area along the left-right axis of the guide surfaces is greater than that along the front-back axis. If angle alpha (α) is 120 deg, the cosine and sine functions indicate that the ratio of projected areas is {square root}3 (square root of 3): 1, i.e., approximately 1.7:1.  
         [0079]    Referring now to FIGS.  5  and FIG. 6, a third embodiment of the present invention includes a pair of gibs  5   c ,  6   c . Gibs  5   c ,  6   c  have a generally concave shape relative to a slide  2   c . As above, gibs  5   c ,  6   c  guide a slide  2   c  during pressing operations.  
         [0080]    It should be noted that the difference between the second and the third embodiments of the present invention is that respective slides  2   b ,  2   c  have opposite (convex/concave) shapes relative to respective supporting gibs  5   b ,  6   b  and  5   c ,  6   c . There are no other structural differences.  
         [0081]    In the third embodiment, angle alpha (α) between respective liners  11 ,  11  is also approximately 120 deg. During operation, where there is little temperature difference between slide  2   c  and gibs  5   c ,  6   c , there is little beneficial difference between the second and the third embodiments.  
         [0082]    However, a benefit does exist in the second embodiment when slide  2   c  reaches a temperature higher than a temperature of gibs  5   c ,  6   c . Such a temperature difference permits thermal deformation of slide  2   c  that is greater than a thermal deformation of gibs  5   c ,  6   c . In conditions of thermal anisotropy, the second embodiment provides greater compensation for thermal deformation. As a result, the present invention is easily adaptable to both precision pressing operations and variable operating environments.  
         [0083]    Referring now to FIGS. 7 and 8, a fourth embodiment of the present invention includes a slide  2   d  operating between a pair of gibs  5   d ,  6   d .  
         [0084]    A pair of bolt  17 ,  17  secures respective gib  5   d ,  6   d  to frame  1  on opposite sides of slide  2   d . A set of screws (not shown) secure a set of liners  11 ,  11  to gib  6   d . Another set of screws (not shown) secure a second set of liners  11 ,  11  to gib  5   d . A bolt  22  secures each block  21 ,  21  to each side of slide  2   d  opposite respective gibs  5   d ,  6   d.    
         [0085]    Spherical cavities  18 ,  18  are disposed in respective blocks  21 ,  21 . A spherical shoe  20  rotatably fits within each block  21 . A flat sections on each spherical shoe  20 ,  20  allows sliding contact with respective liners  11 ,  11  on each gib  5   d ,  6   d , as will be explained.  
         [0086]    In this embodiment, gibs  5   d ,  6   d  and wedge  12  are narrower than in the previous embodiments. Similarly, gib holders  13 ,  14  are smaller in overall dimension. In the fourth embodiment, gib  6   d  sits in a groove (shown but not numbered) in frame  1 . A single bolt  17  threadably secures gib  6   d  to frame  1  opposite slid  2   d . A single bolt  17  similarly secures and fixes wedge  12  and gib  5   d  to frame  1 .  
         [0087]    An assembly method for the fourth embodiment is similar to the assembly methods for the second and third embodiments. During assembly of the fourth embodiment, bolts  22 ,  22  secure respective blocks  21 ,  21  to slide  2   d . Spherical shoes  20 ,  20  are then inserted into respective cavities  18 ,  18 . Gib  6  is secured to frame  1  and receives the assembled slide  2   d . Gib holders  13 ,  14 , wedge  12  and gib  5  are installed and adjusted. After adjustment, bolts  17  secure wedge  12  and gib  5   d  to frame  1 .  
         [0088]    During operation, gibs  5   d ,  6   d  are formed in a general ‘V-shape.’ A liner  11  is positioned on each side of the V-shape. Each shoe  20  provides two corresponding contact surfaces opposite each liner  11 . An angle beta (β) is defined between each side of the V-shape. Angle beta (β) is approximately 120 degrees.  
         [0089]    As an advantage, each shoe  20  replaces previous multiple shoes thereby reducing cost while maintaining precision. In other words, the multiple spherical shoes from the second and the third embodiments are moved as close together as possible and combined.  
         [0090]    The fourth embodiment is particularly advantageous for providing precision operations where space is limited and press  50  or a slide  2   d  must be small.  
         [0091]    In each embodiment discussed above, the combination of at least one spherical shoe  7 - 9  having a flat guide surface sliding along a corresponding gib operates as an easy means for eliminating eccentric force and slide misalignment.  
         [0092]    The simple rotation of respective spherical shoes easily maintains planar contact between respective liners  1   1  and the contact surfaces of respective shoes. This design prevents the formation of line contacts, the breakdown of lubrication and minimizes scorching, scoring and equipment failure.  
         [0093]    As an additional benefit to the present design, since gibs are easily adjusted to a clearance of roughly zero, high precision is easily achieved with no need for a strengthening guide post (not shown) on a die (not shown).  
         [0094]    The present design allows easy adaptation to a variety of production sizes, processing needs, and temperature gradients all while maintaining high precision, simple manufacture, and simple assembly.  
         [0095]    The present design also easily compensates for eccentric forces placed on the slide during regular operation. According to the present invention, the spherical shoes, corresponding cavities, and angular gib faces easily compensate for any eccentric force and maintain parallel operation. As a result, equipment life is extended, maintenance costs reduced, and on-stream time maximized.  
         [0096]    Although only a single or few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the 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 spirit and scope of this invention as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described or suggested herein as performing the recited function and not only structural equivalents but also equivalent structures. Thus, for example, although a nail, a screw, and a bolt may not be structural equivalents in that a nail relies entirely on friction between a wooden part and a cylindrical surface, a screw&#39;s helical surface positively engages the wooden part, and a bolt&#39;s head and nut compress opposite sides of at least one wooden part, in the environment of fastening wooden parts, a nail, a screw, and a bolt may be readily understood by those skilled in the art as equivalent structures.  
         [0097]    Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those 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.