Patent Publication Number: US-11376807-B2

Title: Internally-driven press assembly

Description:
TECHNICAL FIELD 
     This disclosure relates to presses and more particularly to presses for performing a work operation on a workpiece. 
     BACKGROUND 
     Presses may be used for a myriad of mechanical fabricating operations such as piercing, punching, shape forming, resistance welding or the like. Various presses have been proposed and utilized to perform mechanical fabricating operations. Generally, presses in which a large force is required to perform the desired fabrication operation have tended to be unduly large and cumbersome and, conversely, smaller, less cumbersome presses are often unsatisfactory where a large force is required to perform the desired fabrication operation. Various attempts have been made to provide a relatively small press capable of generating a relatively high force at the fabricating tool, but the commercial application of these presses has been limited by problems related to leakage, durability, and the like. 
     Among the art considered in preparing this patent application are these references: U.S. Pat. No. 4,916,932 to Obrecht et al. and U.S. Pat. No. 4,959,989 to Obrecht et al., which are directed to presses for performing a work operation on a workpiece. 
     SUMMARY 
     In at least one approach, a press assembly is provided. The press assembly may include an elongated guide. The press assembly may further include a ram that may be at least partially mounted in the guide channel and axially movable relative to the frame. The ram may include an internal chamber. The press assembly may further include a fabricating tool that may be disposed proximate an outboard end portion of the ram. The press assembly may further include a cylinder that may be disposed within the internal chamber and that may include a cylindrical bore. The cylinder may be secured to the ram such that the cylinder is fixed relative to the ram axially and rotationally so that the cylinder and ram move in unison. The press assembly may further include a spindle. The spindle may have a driving end region. The spindle may further have a driven end region opposite the driving end region and that may be disposed at least partially within the cylindrical bore. The press assembly may further include means for imparting rotary motion to the spindle to effect a rotational movement of the driving end region and an axial displacement of the cylinder and the ram. 
     At least a portion of the cylindrical bore may define an internally-threaded cylindrical bore. At least a portion of the driven end region of the spindle may include an externally-threaded driven end region. Roller screws may be disposed between the externally-threaded driven end region and the internally-threaded cylindrical bore. The roller screws may be planetary roller screws that may be rotatable about the externally-threaded driven end region. Rotation of the planetary roller screws about the externally-threaded driven end region may produce the axial displacement of the cylinder and the ram. 
     The cylinder may include a recess that may be formed in an external surface of the cylinder. The ram may include a through-hole that may be disposed in alignment with the recess when the cylinder is seated within the internal chamber. A key may be sized to extend through the through-hole and to interface with the recess. A removable fastener that may extend through a through-hole of the key and into engagement with the ram to removably secure the key to the ram. The key may be a T-shaped key that may have a head region that interfaces with the ram and a narrowed neck region that interfaces with the ram and the recess of the cylinder. The recess may internally define opposing surfaces and an intermediate surface that may extend between the opposing surfaces. The key may interface with the intermediate surface to inhibit rotational movement of the cylinder relative to the ram, and may interface with the opposing surfaces to inhibit axial movement of the cylinder relative to the ram. 
     The cylinder may include a plurality of opposing recesses formed in an external surface of the cylinder. The ram may include opposing through-holes, each being disposed in alignment with an individual recess of the opposing recesses. The press assembly may further include removable keys that may extend through the opposing through-holes and that may interface with the opposing recesses to prevent axial and rotational movement of the cylinder relative to the ram. 
     The press assembly may further include a capping block that may be removably secured to an inboard end of the ram to define at least a portion of the internal chamber. The capping block may include an aperture for receiving the spindle therethrough. 
     The cylinder may be internally-axially-driven by the spindle. The ram may be externally-axially-guided by the frame. The spindle may be axially fixed relative to the means for imparting rotary motion. The cylinder may be axially moveable relative to the means for imparting rotary motion. 
     In at least one approach, a press assembly may be provided. The press assembly may include a means for imparting rotary motion, and a ram that may be axially displaceable relative to the means for imparting rotary motion. The press assembly may further include a fabricating tool that may be secured to an end of the ram. The press assembly may further include an inverted roller screw assembly that may be adapted to receive a rotational movement from the means for imparting rotary motion and to axially displace the ram. The inverted roller screw assembly may include a cylinder that may include an internally-threaded cylindrical bore. The cylinder may be secured to the ram such that the cylinder is rotatably and axially fixed relative to the ram. The inverted roller screw assembly may further include a spindle that may include a threaded portion that may extend within at least a portion of the internally-threaded cylindrical bore. The inverted roller screw assembly may further include a plurality of roller screws that may be disposed between and in threaded engagement with the cylinder and the spindle. 
     The cylinder may define a first central axis. The fabricating tool may define a second central axis that is offset from the first central axis. The second central axis may be vertically and/or horizontally offset from the first central axis. 
     In at least one approach, a method of operating a press assembly may be provided. The method may include actuating a means for imparting rotary motion to rotate a spindle. Rotation of the spindle may effect rotation of planetary roller screws disposed about an outer perimeter of the spindle. Rotation of the planetary roller screws may effect an axial movement, and not rotational movement, of a cylinder that extends about the planetary roller screws. Axial movement of the cylinder may effect a corresponding axial movement of a ram that is rotationally and axially fixed to the cylinder. The method may further include actuating the means for imparting rotary motion to engage a workpiece with a fabricating portion of the ram. 
     The method may further include, prior to actuating the means for imparting rotary motion to rotate a spindle, providing a removable key within a through-hole of the ram and into engagement with the cylinder at a recess disposed in an external surface of the cylinder such that the key prohibits axial and rotational movement of the cylinder relative to the ram. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a press assembly. 
         FIG. 2  is a partially exploded view of a press. 
         FIG. 3  is a cross-sectional view taken along line  3 - 3  of  FIG. 2 . 
         FIG. 4  is a perspective view of an inverted roller screw assembly with a portion of the cylinder removed. 
         FIG. 5  is an exploded view of a portion of the press. 
         FIG. 6  is a cross-sectional view taken along line  6 - 6  of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments may take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures may be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations. 
     A press assembly may be used to fabricate a workpiece. As discussed in greater detail elsewhere herein, the press assembly may include an inverted roller screw assembly that internally drives a ram. The inverted roller screw assembly may include a spindle, planetary roller screws disposed about an outer perimeter of the spindle, and an internally-threaded cylinder disposed about the planetary roller screws. The cylinder may be axially- and rotationally-fixed within an internal chamber of the ram. 
     In at least one approach, to operate the press assembly, a means for imparting rotary motion, such as a motor, may be actuated to rotate the spindle. Rotation of the spindle may effect rotation of the planetary roller screws about a central axis of the spindle. Rotation of the planetary roller screws may effect an axial movement—and not rotational movement—of the cylinder. As the cylinder is keyed to the ram, axial movement of the cylinder may effect a corresponding axial movement of the ram. Axial movement of the ram may be guided within an elongated guide of the press. In this way, the ram—and a fabricating tool secured to a forward face of the ram—may be driven toward, and into engagement with a workpiece to perform a work operation on the workpiece. The work operation may include one or more of piercing, punching, shape forming, welding, or the like. 
     Referring now to  FIG. 1 , a press assembly  10  may include a press  12 , a base  14 , and a die  16 . The press  12  may be secured to the base  14 , for example, through a press retainer plate  20 . In this way, at least a portion of the press  12  may be rigidly secured to base  14 . 
     The base  14  may include side plates  22  and  24 . In at least one approach, the side plates  22  and  24  may include cutouts that define a generally C-shaped configuration of one or both of the plates  22 ,  24 . Other side plate configurations are expressly contemplated. 
     The die  16  may be secured to the base  14  through a die retainer plate  26 . The press  12  may include a fabricating tool  30  that may be movable relative to the die  16 . For example, in a first configuration, the fabricating tool  30  may be spaced apart from the die  16 . In this configuration, a workpiece may be provided between the fabricating tool  30  and the die  16 ; for example, adjacent to the die  16 . The fabricating tool  30  may be moved to a second configuration in which the fabricating tool  30  engages the workpiece. As will be appreciated, upon engagement, further movement of the fabricating tool  30  may perform a work operation on the workpiece. 
     As discussed, the press  12  may be rigidly secured to the base  14  such that at least a portion of the press  12  is movably fixed relative to the base  14 . The die  16  may also be rigidly secured to the base  14 . In still another approach, one or both of the press  12  and the die  16  may be slidably secured to the base  14 . For example, the press  12  may be slidably secured to the base  14  such that a frame of the press  12  is axially movable relative to at least a portion of the base  14 . In this way, the press assembly  10  may be a self-equalizing press assembly. 
     Referring to  FIG. 2 , a press  12  may include a frame, referred to herein as elongated guide  40 . The elongated guide  40  may in the form of a guide frame, guide channel, guide member, or other suitable structure. The elongated guide  40  may be formed of one or more walls, which may include guide walls such as bottom wall  42 , opposing side walls  44 , and top wall  46 . The one or more guide walls of the elongated guide  40  may define a guide channel  50  therebetween. The guide walls may be spaced such that the elongated guide  40  may receive a ram  60  within the guide channel  50 . The ram  60  may have a substantially polygonal cross-sectional profile; for example, when view in the X-Z plane. 
     The elongated guide  40  may act as a guide as the ram  60  moves axially within the guide channel  50 . For example, the bottom wall  42  may inhibit movement of the ram  60  in a first Z direction, the top wall  46  may inhibit movement of the ram  60  in a second Z direction opposite the first Z direction, and the opposing side walls  44  may inhibit movement of the ram  60  in the X direction. In this way, the elongated guide  40  may guide the ram  60  as it moves axially in the Y direction. 
     The press  12  may further include a means for imparting rotary motion. Means for imparting rotary motion may include electric motors, hydraulic motors, pneumatic motors, engines, turbines, and their equivalents. For example, the means for imparting rotary motion may include a motor  62 , which may include a servo motor. The means for imparting rotary motion may be connected to a coupler, which may be a gear reducer  64 . The gear reducer  64  may include, for example, an inline planetary gearbox. 
     As shown in  FIG. 3 , a spindle  70  may extend from the gear reducer  64 . The gear reducer  64  may effect a rotational force at a first end portion, also referred to herein as the driving end region  74 , of the spindle  70 . This may cause the spindle  70  to rotate about a central axis  72 . The spindle  70  may be secured to the gear reducer  64  such that the spindle  70  is axially fixed relative to the gear reducer  64 . In this way, the spindle  70  may be rotated about the central axis  72 , but axial movement of the spindle  70  along the central axis  72  may be inhibited. 
     The spindle  70  may extend through a bearing assembly  80  that may be housed in a bearing housing  82 . The bearing housing  82  may cooperate with the walls of the elongated guide  40  to at least partially define the guide channel  50 . 
     Referring momentarily to  FIG. 4 , the spindle  70  may be a component of a roller screw assembly, such as inverted roller screw assembly  90 . A roller screw assembly, which may also be referred to herein as a planetary roller screw or satellite roller screw, may be a screw-type actuator. The roller screw assembly may be a mechanical device adapted to convert rotational motion to linear motion, or vice versa. A roller screw assembly for use herein may include one or more of a standard roller screw assembly, an inverted roller screw assembly, a recirculating roller screw assembly, and a bearing ring roller screw assembly. Differential roller screws, which may be variants of the standard and recirculating types, may also be utilized. 
     An inverted roller screw assembly  90  may include one or more (e.g., two opposing) carrier plates  92  disposed about a second end portion of the spindle  70 , referred to herein as a driven end region  76 . The carrier plates  92  may secure a plurality of rollers, referred to herein as roller screws  94 , about the driven end region  76  of the spindle  70 . Meshed ring gears  96  may be provided proximate the carrier plates  92 . For example, a flange portion of a ring gear  96  may extend between the spindle  70  and the carrier plates  92 . The carrier plates  92  may be rotatable about the flange portion of the ring gear  96 . The ring gears  96  may be rotatably fixed to the spindle  70 , and may be disposed in meshed engagement with the roller screws  94 . In this way, rotation of the spindle  70  about the central axis  72  may effect a planetary rotation of the roller screws  94  about the central axis  72 . 
     A cylinder  100  may be disposed about the inverted roller screw assembly  90 . The cylinder  100  defines a cylindrical bore  102 . The cylinder  100  may further define at least one internal thread  104  that extends within the cylindrical bore  102 . In this way, the cylinder bore  102  may be at least partially internally-threaded. The internal threads  104  of the cylinder  100  may receive threads  106  of the roller screws  94 . In this way, as the roller screws  94  are rotated about the central axis  72 , the roller screws  94  act on the internal threads of the cylinder  100 . As previously discussed, the spindle  70  is axially fixed such that the movement of the spindle  70  along the central axis  72  is substantially inhibited. As such, rotation of the roller screws  94  about the central axis  72  effects a linear force on the internal threads  104  of the cylinder  100  and drives the cylinder  100  along the central axis  72 . 
     Referring again to  FIG. 3 , the cylinder  100  may extend within the ram  60 . More particularly, the cylinder  100  may extend within an internal chamber  110  of the ram  60 . The internal chamber  110  may be a cylindrical internal chamber  110  sized to receive the cylinder  100 . The internal chamber  110  may include an expanded region adapted to receive a flange of an end portion of the cylinder  100 . 
     An intermediate cap, also referred to herein as capping block  112 , may be secured (e.g., removably secured) to the ram  60 . In at least one approach, the capping block  112  is a multi-piece (e.g., two piece) capping block. A multi-piece capping block may facilitate installation about the spindle  70 . 
     In the installed configuration, the capping block  112  may interface both an end region of the ram  60  and an end region (e.g., including the flange) of the cylinder  100 . The capping block  112  may include a spindle aperture that receives the spindle  70  therethrough. A sealing ring  114  may be provided within the spindle aperture to interface a portion of the capping block  112  and the spindle  70 . The sealing ring  114  may cooperate with the spindle  70 , the capping block  112 , and the cylindrical bore  102  of the cylinder  100  to provide a fluid-tight (or substantially fluid-tight) fluid chamber. A fluid inlet  116  may permit selective fluid communication with the fluid chamber. The fluid inlet  116  may also be in fluid connection with a fluid source, such as an oil well. In this way, the fluid chamber may receive oil from the fluid source, and the fluid chamber may act as an internal bath chamber that lubricates the cylindrical bore  102  of the cylinder  100  and components of the inverted roller screw assembly  90 . 
     As discussed, the cylinder  100  may be secured to the ram  60  such that the cylinder  100  is axially fixed to the ram  60 . As such, axial movement of the cylinder  100  (e.g., along an axis parallel to central axis  72 ) may effect a corresponding axial movement of the ram  60 . In this regard, a key system may be utilized to axially secure the ram  60  to the cylinder  100 . 
     Referring to  FIG. 5 , the cylinder  100  may be provided with one or more recesses, also referred to herein as key receptacles  120 . A key receptacle  120  may be, for example, machined into an outer cylindrical surface of the cylinder  100 . In still another approach, a key receptacle  120  may be integrally formed with the cylinder  100 . 
     A key receptacle  120  may extend through less than an entire wall thickness of the cylinder  100 . As such the key receptacles  120  may not interface the wall defining the internally-threaded cylinder bore  102 . In at least one approach, the key receptacle  120  may internally define opposing walls or surfaces  122 , and an intermediate wall or surface  124  extending between the opposing surfaces  122 . In the orientation depicted  FIG. 5 , the opposing surfaces  122  may be referred to as vertical walls, and the intermediate surface  124  may be referred to as a horizontal wall. Furthermore, as shown, the intermediate surface  124  may be disposed, and may extend, orthogonally relative to the opposing surface  122 . Other key receptacle geometries are expressly contemplated. 
     The ram  60  may include one or more through-holes  130 . The through-holes  130  may be disposed in alignment with corresponding key receptacles  120 . The through-holes  130  may be defined by one or more planar (e.g, vertical or substantially vertical) walls  132 . The through-holes  130  may also be defined by one or more shelf walls  134  that may extend, for example, substantially orthogonally from the planar walls  132 . 
     A key  140  may be provided to interface the ram  60  (e.g., at a through-hole  130 ) and the cylinder  100  (e.g., at the key receptacle  120 ). In at least one approach, the key  140  is a T-shaped key having a neck region  142  and a head region  144  that extends from the neck region  142 . The neck region  142  may include vertical walls and a bottom wall that extends between the vertical walls. The head region  144  may extend beyond at least one of the vertical walls of the neck region  142  such that a dimension (e.g., length) of the head region  144  is greater than a corresponding dimension of the neck region  142 . 
     The key  140  may be received within a through-hole  130  of the ram  60 . In at least one approach, the head region  144  may engage the shelf walls  134  within the through-hole  130 . The head region  144  and shelf walls  134  may have aligned fastener interfaces that permit a fastener  146  to secure the key  140  to the ram  60  when the key  140  is in the installed configuration. 
     Also in the installed configuration, the neck region  142  of the key  140  may interface the key receptacle  120  of the cylinder  100 . For example, vertical walls of the neck region  142  may engage the opposing surfaces  122  of the key receptacle  120 . In this way, the neck region  142  may inhibit axial movement (e.g., in the Y direction) of the cylinder  100  relative to the ram  60 . Furthermore, the bottom wall of the neck region  142  may engage the intermediate surface  124  of the key receptacle  120 . In this way, the neck region  142  may further inhibit rotational movement of the cylinder  100  relative to the ram  60 . 
     In the approach shown, the key system may include two through-holes  130  disposed at and extending through opposite walls of the ram  60 , two key receptacles  120  disposed on opposite surfaces of the cylinder  100 , and two keys  140 , each extending through a through-hole  130  and a corresponding key receptacle  120 . 
     Although described herein as a key system, other suitable approaches are expressly contemplated for axially and rotatably locking the ram  60  with the cylinder  100 . For example, one or more removable fasteners (e.g., threaded fasteners) may inserted through the ram  60  and at least a portion of the cylinder  100  to lock the cylinder  100  to the ram  60 . Other approaches may include the use of wedges, latches, locks, locking rods, etc. to axially and rotatably lock the ram  60  with the cylinder  100 . 
     Referring to  FIG. 6 , a fabricating assembly may include a tool plate  150  that may be removably secured to a front face of the ram  60 . A retainer  152  may be removably secured to the tool plate  150 . A tool guide  154  may also be rotatably fixed relative to the tool plate  150 , for example, by a plurality of spring-loaded rods  156 . A fabricating tool  30  may extend through the retainer  152  and through the tool guide  154 . The fabricating tool  30  may be, for example, a ball lock punch, or any fabricating tool for use with performing a work operation on a workpiece. 
     As shown in  FIG. 6 , the press assembly  10  contemplated herein permits a fabricating tool  30  to be driven along an axis  160  that may be offset from the central axis  72  of the spindle  70 . The offset may be along the X-axis, the Y-axis, the Z-axis, or any combination thereof. For example, the axis  160  may be horizontally offset (as indicated by “H”), vertically offset (as indicated by “V”), or both horizontally offset and vertically offset from the central axis  72  of the spindle  70 . This may be due to the uniform force extorted across the front face of the ram  60 , which may be evenly distributed across the tool plate  150 . As such, the force in the axial direction is not contingent upon the central axis of the fabricating tool  30  being coaxial with the central axis  72  of the spindle  70 , or the central axis of the cylinder  100  (which may be coaxial with central axis  72 ). 
     While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments may be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics may be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes may include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications. 
     
       
         
           
               
             
               
                   
               
               
                 Table of Reference Numerals: 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 10 
                 press assembly 
               
               
                 12 
                 press 
               
               
                 14 
                 base 
               
               
                 16 
                 die 
               
               
                 20 
                 press retainer plate 
               
               
                 22 
                 side plate 
               
               
                 24 
                 side plate 
               
               
                 26 
                 die retainer plate 
               
               
                 30 
                 tool 
               
               
                 40 
                 elongated guide 
               
               
                 42 
                 bottom wall 
               
               
                 44 
                 side walls 
               
               
                 46 
                 top wall 
               
               
                 50 
                 guide channel 
               
               
                 60 
                 ram 
               
               
                 62 
                 motor 
               
               
                 64 
                 gear reducer 
               
               
                 70 
                 spindle 
               
               
                 72 
                 central axis 
               
               
                 74 
                 driving end region 
               
               
                 76 
                 driven end region 
               
               
                 80 
                 bearing assembly 
               
               
                 82 
                 bearing housing 
               
               
                 90 
                 inverted roller screw assembly 
               
               
                 92 
                 carrier plates 
               
               
                 94 
                 roller screws 
               
               
                 96 
                 ring gear 
               
               
                 100 
                 cylinder 
               
               
                 102 
                 cylindrical bore 
               
               
                 104 
                 internal threads 
               
               
                 106 
                 threads 
               
               
                 110 
                 internal chamber 
               
               
                 112 
                 capping block 
               
               
                 114 
                 sealing ring 
               
               
                 116 
                 fluid inlet 
               
               
                 120 
                 key receptacle 
               
               
                 122 
                 opposing surfaces 
               
               
                 124 
                 intermediate surface 
               
               
                 130 
                 through-hole 
               
               
                 132 
                 planar wall 
               
               
                 134 
                 shelf walls 
               
               
                 140 
                 key 
               
               
                 142 
                 neck region 
               
               
                 144 
                 head region 
               
               
                 146 
                 fastener 
               
               
                 150 
                 tool plate 
               
               
                 152 
                 retainer 
               
               
                 154 
                 tool guide 
               
               
                 156 
                 rods 
               
               
                 160 
                 axis