Patent Publication Number: US-11045856-B2

Title: Redraw sleeve assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the National Stage of International Application No. PCT/GB2017/051951 filed Jul. 3, 2017, which claims the benefit of GB application number 1613055.1, filed Jul. 28, 2016, the disclosures of which are incorporated herein by reference in their entirety. 
     TECHNICAL FIELD 
     The present invention relates to a can bodymaker and in particular to a can bodymaker comprising a redraw sleeve assembly. The invention also relates to a redraw sleeve alignment mechanism and a toolpack module incorporating a redraw sleeve alignment mechanism for use with a can bodymaker and to a method of setting up a can bodymaker. 
     BACKGROUND 
     In known bodymakers for the production of thin-walled metal cans by the so-called “drawing and wall-ironing” (DWI) process, cups are fed to the bodymaker and carried by a punch on the end of a ram through a series of dies to obtain the desired size and thickness of the can. The series of dies may include a redraw die for reducing the diameter of the cup and lengthening its sidewall, and one or more ironing dies for wall-ironing a cup into a can body. Ultimately, the can body carried on the punch may contact a bottom forming tool so as to form a shape such as a dome on the base of the can. An exemplary bodymaker is described in WO9934942. 
     For the DWI process to be successful, it is essential that a cup supplied to the bodymaker is positioned accurately in the path of the punch and held in place while the punch draws the base of the cup through the redraw die. In existing bodymakers, this is achieved by precise alignment of a cup locator on the front of the bodymaker cradle with a redraw sleeve mounted on the front of a reciprocating redraw carriage. Prior to the punch contacting the cup, the redraw sleeve enters the cup and forces the base of the cup against the redraw die. Misalignment of the redraw carriage may cause incorrect positioning of the cup with respect to the punch and the redraw die, leading to damage or reduced uniformity in the produced cans, particularly for thin-walled metal cans. Such misalignment may also increase wear on or damage the machine components. 
     Alignment of known bodymakers is a time consuming process which requires production to be halted. The high volume nature of the can industry means that lost production time can be very costly for can producers. Additionally, alignment procedures for known bodymakers require significant skill and attention to ensure that the machines can be operated safely and efficiently. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the present invention there is provided a can bodymaker comprising a ram and a redraw sleeve assembly for holding a cup or other preform article against a redraw die. The redraw sleeve assembly comprises: a redraw sleeve; a redraw carriage to which the redraw sleeve is removably coupled, the redraw carriage being driven in a reciprocating motion along an axis; and a redraw sleeve alignment mechanism. The redraw sleeve alignment mechanism comprises: a redraw sleeve module having one or more bearings defining a passage through which the redraw sleeve moves and a bearing adjustment mechanism to facilitate radial alignment of the redraw sleeve module with the redraw die. The coupling between the redraw carriage and the redraw sleeve permits variable radial offset, relative to said axis, between the two components. 
     A preform article includes any article suitable for producing can bodies through a DWI process. During the drawing part of the DWI process, the redraw sleeve is pushed into the cup or preform article by the redraw carriage so that the base of the can or preform article is held against the redraw die. The redraw sleeve is hollow to allow the ram to pass through. 
     The bodymaker may comprise a magnetic coupling for coupling the redraw carriage and the redraw sleeve. 
     The redraw sleeve alignment mechanism may comprise a redraw sleeve module housing fixed relative to the can bodymaker, the redraw sleeve module being located within the redraw sleeve module housing whereby said bearing adjustment mechanism permits radial positioning of the redraw sleeve module within the redraw sleeve module housing. 
     The bearing adjustment mechanism may comprise one or more cams attached to the redraw sleeve module housing. The or each cam may be coupled to a rod extending coaxially through the redraw sleeve module housing and being accessible via a surface of the redraw sleeve module housing opposed to the redraw carriage, rotation of the or each rod causing rotation of the associated cam. 
     The one or more bearings of the redraw sleeve module may be fixed within a substantially cylindrical frame and the substantially cylindrical frame located within said redraw sleeve module housing. The bearing adjustment mechanism permits radial positioning of the redraw sleeve module by moving the cylindrical frame within the redraw sleeve module housing. The one or more bearings of the redraw sleeve module may comprise a pair of bearings, each bearing being located within the cylindrical frame. The cylindrical frame may comprise a circumferential groove for supplying lubricant to the redraw sleeve, the groove being located between the pair of bearings. The redraw sleeve module may comprise a pair of lip seals attached to the cylindrical frame and located on, respective, opposite sides of the pair of bearings. 
     The redraw sleeve alignment mechanism may comprise a bracket fixed to the can bodymaker, the redraw sleeve module housing being fixed to the can bodymaker by means of the bracket. The redraw sleeve alignment mechanism may further comprise a locator for holding and locating a cup or other preform article in front of the redraw sleeve. The locator is coupled to the bracket and the bracket has a locator adjustment mechanism to facilitate radial alignment of the locator within the bracket. 
     The locator adjustment mechanism may comprise one or more cams attached to the bracket. The or each cam of the locator adjustment mechanism may be coupled to a rod extending coaxially through the bracket and being accessible via a surface of the redraw sleeve module housing opposed to the redraw carriage. Rotation of the or each rod causes rotation of the associated cam. 
     According to a second aspect of the present invention there is provided a method of setting up a can bodymaker. The method comprises the steps of: providing a redraw sleeve module for supporting a redraw sleeve; moving the bearing to align the redraw sleeve radially with respect to a redraw die attached to the bodymaker, and fixing the redraw sleeve module in place; and coupling the redraw sleeve to a redraw carriage of the bodymaker. 
     The method may further comprise locating the redraw sleeve within the redraw sleeve module either before or after the step of moving the redraw bearing. 
     The step of moving the redraw sleeve module may comprise rotating one or more cams acting against the redraw sleeve module. The redraw sleeve module may be located within a redraw sleeve module housing. The or each cam acts between the redraw sleeve module housing and the redraw sleeve module. 
     The method may further comprise providing a locator for a cup or other preform article within a bracket fixed to the redraw sleeve module housing, and moving the locator radially within the bracket to align the locator with respect to the redraw die. 
     According to a third aspect of the present invention there is provided a redraw sleeve alignment mechanism for use with a can bodymaker. The redraw sleeve alignment mechanism configured to align a redraw sleeve with a redraw die and comprises: a redraw sleeve module having one or more bearings defining a passage through which the redraw sleeve moves; and a bearing adjustment mechanism to facilitate radial alignment of the redraw sleeve module with the redraw die. 
     The redraw sleeve alignment mechanism may comprise a redraw sleeve module housing for coupling to the can bodymaker in a fixed position. The redraw sleeve module is located within the redraw sleeve module housing whereby the bearing adjustment mechanism permits radial positioning of the redraw sleeve module within the redraw sleeve module housing. 
     The redraw sleeve alignment mechanism may comprise a bracket for coupling the redraw sleeve module housing to the can bodymaker in a fixed position. 
     The redraw sleeve alignment mechanism may comprise a locator for holding and locating a cup or other preform article in front of the redraw sleeve. The locator is coupled to the bracket and the bracket has a locator adjustment mechanism to facilitate radial alignment of the locator within the bracket. 
     According to a fourth aspect of the present invention there is provided a toolpack module for use with a can bodymaker. The toolpack module comprises: a frame; a redraw die coupled to the frame; and a redraw sleeve alignment mechanism according to the third aspect of the present invention. The redraw sleeve alignment mechanism is coupled to the frame. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective schematic view of a bodymaker according to an embodiment of the invention; 
         FIG. 2  is a perspective schematic view of the toolpack module including the redraw sleeve alignment mechanism shown in  FIG. 1 ; 
         FIG. 3  is a vertical section schematic view through the redraw sleeve assembly shown in  FIG. 1 ; 
         FIG. 4  is a section schematic view of the redraw sleeve alignment mechanism shown in  FIGS. 1, 2 and 3 ; 
         FIG. 5  is a perspective schematic view of the redraw sleeve alignment mechanism shown in  FIGS. 1 to 4 ; and 
         FIG. 6  is a flow chart illustrating a method of setting up the bodymaker of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     In order to address the problems associated with aligning the redraw sleeve of the conventional bodymaker, it is proposed here to enable a temporary decoupling of the redraw sleeve from the redraw carriage. Moreover, re-coupling between the redraw sleeve and the redraw carriage allows for radial misalignment of the redraw carriage and the redraw sleeve. In practice, this means that there is no need for a fine alignment of the redraw carriage with the redraw die. Only the redraw sleeve needs to be so aligned, and this can be carried out relatively easily. 
       FIG. 1  shows a perspective schematic view of a bodymaker  1  for making can bodies from cups drawn from sheet metal. The bodymaker  1  comprises a reciprocating ram  2  with a punch (not shown) mounted on one end. During a forward stroke of the ram  2 , the punch contacts a cup (not shown) held in the path of the ram by a redraw sleeve assembly  3  attached to a toolpack module  101 . The punch pushes the cup through a redraw die (not shown) to form an elongated cup body. The elongated cup body is carried on the punch through one or more ironing dies, housed within the toolpack module  101 , to further elongate and thin the cup body before finally contacting a bottom forming tool or “domer”  4  so as to form a shape such as dome on the base. On a return stroke of the ram  2 , the formed can body is removed from the punch and transported away from the ram axis by a can discharge turret  5 . 
     The redraw sleeve assembly  3  comprises a redraw sleeve  7 , a redraw carriage  8  and a redraw sleeve alignment mechanism  103  for aligning the redraw sleeve  7  with the one or more ironing dies. The cup is supplied to the redraw sleeve assembly  3  by an infeed mechanism  6  located above the ram  2 . The cup is held in position during the redraw process by a generally hollow cylindrical redraw sleeve  7  which is aligned coaxially with the ram  2  and has a central bore which allows the punch to pass therethrough. A rear end of the redraw sleeve  7  is coupled to a redraw carriage  8  which is driven in a reciprocating motion by a pair of push rods  9 ,  10  located on opposite sides of the ram  2 . A cup locator (not shown) mounted on the redraw sleeve alignment mechanism  103  receives the cup while the punch and the redraw sleeve  7  are in a retracted position with respect to the redraw sleeve assembly  3 . During the forward stroke of the ram  2 , prior to the punch contacting the cup, the redraw sleeve  7  enters the open end of the cup and forces the cup into contact with the redraw die. The redraw sleeve  7  holds the cup against the redraw die as the punch pushes the base of the cup through an aperture of the redraw die which is of smaller diameter than the cup. As the cup is drawn through the redraw die by the punch, the cup reduces in diameter and its sidewall lengthens. The elongated cup is then carried away from the redraw assembly  3  by the punch. 
       FIG. 2  is a perspective schematic view of the toolpack module  101  including the redraw sleeve alignment mechanism  103  attached to its front face. Note that the redraw sleeve  7  is not shown in  FIG. 2 . The redraw die  11  is held rigidly in place within a bodymaker cradle  12  of the toolpack module  101 . 
       FIG. 3  shows a vertical section schematic view through the redraw sleeve assembly  3  shown in  FIG. 1 , after the redraw process has been completed. 
       FIGS. 4 and 5  show, respectively, a vertical section schematic view and a perspective schematic view of the redraw sleeve alignment mechanism  103  shown in  FIGS. 1, 2  and  3 . Certain features of the redraw sleeve alignment mechanism  103  may be more clearly understood by reference to two or more of the Figures simultaneously. 
     In the configuration shown in  FIG. 3 , the punch has passed through the redraw sleeve assembly  3  pushing the cup with it, and the (leftmost end of the) redraw sleeve  7  is now in contact with the annular redraw die  11 , and in particular with a redraw die insert  11   a . The redraw sleeve  7  is supported within the redraw sleeve alignment mechanism  103  which comprises a generally cylindrical redraw sleeve module  13  (see the dashed box shown in  FIG. 4 ) and a module housing  3   a . The radial position of the redraw sleeve module  13  within the module housing  3   a  can be adjusted as discussed below. 
     The redraw sleeve module  13  maintains the alignment of the redraw sleeve  7  with respect to the redraw die  11  as the redraw sleeve  7  moves backwards and forwards in synchronisation with the ram  2 . The rear end of the redraw sleeve  7  is coupled to the redraw carriage  8  so that the linear motion of the redraw carriage  8  is transferred efficiently to the redraw sleeve  7 . 
     The redraw sleeve  7  may be detached from the redraw carriage  8  so that the redraw sleeve can be aligned independently of the redraw carriage  8 . The coupling between the redraw sleeve  7  and the redraw carriage  8  does not require the redraw carriage  8  and the redraw sleeve  7  to be precisely aligned, i.e., the redraw carriage  8  may be radially misaligned with respect to the axis of the redraw sleeve  7 . This flexibility means that it is no longer necessary to align the redraw carriage  8  precisely as the redraw sleeve  7  is now guided by and aligned within the redraw sleeve module  13 . 
     The redraw sleeve  7  is coupled to the redraw carriage  8  using a coupling means that allows the two components to move together axially but which allows for relative axial movement. In one embodiment, strong magnets  16  are fixed to the rear (rightmost) end of the redraw sleeve  7  to engage with the opposed surfaces of the redraw carriage  8 . The magnets  16  and the opposed surfaces may be flat in order to facilitate coupling across a range of radial positions. Other coupling mechanisms can of course be contemplated. For example, the coupling mechanism may be an adjustable clutch or a flexible joint, e.g. a ball and socket joint. 
     In use, the redraw sleeve  7  moves through the redraw sleeve module  13  to force a cup into contact with the redraw die. The cup is received by the cup locator  17  mounted on the end of the redraw sleeve alignment mechanism  103  adjacent to the redraw die. The cup locator  17  can be seen more clearly in the perspective view of  FIG. 5 . The cup locator  17  has a semi-circular cross-section with an inner diameter which is of a slightly larger diameter than the outer diameter of the cup and is arranged to be upward facing so that a cup may drop into position from above. The cup locator  17  is supported by three eccentric cams  18   a - c  (two cams not shown) housed within a bracket  14  of semi-circular cross-section. The radial position of the cup locator  17  with respect to the redraw die may be adjusted by rotating each of the eccentric cams  18   a - c  using a set of three square rods  19   a - c  extending through the bracket  14 . 
     As shown in  FIGS. 4 and 5 , the module housing  3   a  comprises an end of the bracket  14 , the other end of which is attached to the cradle  12  by a pair of opposed flanges  15 ,  15   a  which are bolted together and which each have a cylindrical bore for receiving the redraw die  11  and the ram  2 . The module housing  3   a  further comprises a bridge  20  (see  FIG. 5 ) with a semi-circular cross-section and which is fixed to the end of the bracket  14  by means of vertically extending bolts (not shown). The bridge  20  has approximately the same inner and outer diameter as the bracket  14 , so as to provide a generally cylindrical passage  21  (see  FIG. 4 ) for receiving the bearing  13 . 
     The structure of the redraw sleeve alignment mechanism  103  is best shown in the vertical section view of  FIG. 4 . The redraw sleeve  7  is not shown in this Figure. The redraw sleeve module  13 , which is fitted within the module housing  3   a , comprises a cylindrical bearing frame  13   a  located within a bearing support cylinder  22 . The bearing support cylinder  22  has a cylindrical body  22   a  and a flange  22   b  which extends radially outwards from one end of the body  22   a . The outer diameter of the body  22   a  is smaller than the inner diameter of the passage  21  through the module housing  3   a , resulting in a gap between these components to allow the body  22   a  to be positioned within the passage  21  and its radial position adjusted. As shown in the perspective view of  FIG. 5 , the outer diameter of the flange  22   b  is of substantially the same outer diameter as the module housing  3   a  to allow the flange to be bolted against the (rightmost) end of the module housing  3   a  once the bearing support cylinder  22  has been aligned. 
     The bearing support cylinder  22  may be aligned radially within the module housing  3   a  by adjusting a set of four eccentric cams  31   a - d  (see  FIG. 5 , two cams not shown) which protrude radially into the passage  21  to contact the outer surface of the bearing support cylinder  22 . The four cams  31   a - d  are positioned around the circumference of the passage  21 , with a lower pair  31   a,b  of the cams housed in the bracket  14  and an upper pair  31   c,d  housed in the bridge  20 . Each cam  31   a - d  is fixed to a rod  23   a - d  of square cross section which protrudes from the end of the module housing  3   a . Turning the rods  23   a - d  causes the eccentric cams  31   a - d  to rotate against the bearing support cylinder  22 , thereby allowing the radial position of the bearing support cylinder  22  within the passage  21  to be varied. 
     The vertical section view of  FIG. 4  shows the cylindrical bearing frame  13   a , which is bolted to the bearing support cylinder  22  to form a single unit in which the two components remain locked together in fixed alignment. A ring  26  projects inwardly from the bearing frame  13   a  around halfway along its length. Two cylindrical bearings  26   a,b  are housed within the cylindrical bearing frame  13   a , one on either side of the ring  26 . The bearings  26   a,b  may, for example, be bushings made from PTFE or another low-friction polymer. The ring  26  is slightly recessed with respect to the bearings  26   a,b  to allow the redraw sleeve  3  to be supported by the bearings  26   a,b . Using more than one cylindrical bearing  26   a,b  may improve the stability of the redraw sleeve as it moves through the redraw sleeve module  13 . A circumferential groove  27  is provided in the ring  26  to receive a lubricant such as oil. In use, lubricant from the groove  27  is deposited on the outer surface of the redraw sleeve  7  to reduce friction as the redraw sleeve  7  moves backwards and forwards through the bearings  26   a,b . The bearing frame  13   a  has fixed within it a pair of cylindrical lip seals  25   a,b , one at each end of the frame, for forming a seal against the outer surface of the redraw sleeve  3  so that the lubricant does not leak from the bearing frame  13   a.    
     A cylindrical bore is provided radially through the top of each of the bridge  20  and the bearing locator  22  to accommodate a lubricating device  28  (the top of which is also visible in  FIG. 5 ) for dispensing a lubricant into the circumferential groove  27 . The lubricating device  28  comprises a capped reservoir  29  for containing the lubricant and a dispensing end  30  which allows the lubricant to leak gradually from a small aperture when the bodymaker  1  is in use. The dispensing end  30  is screwed into the bearing  13  so that the small aperture adjoins a hole in the circumferential groove  27  to allow the lubricant to flow therethrough. 
     Although the bearing frame  13   a  has been described as comprising a pair of lubricated bearings  26   a,b , it will be appreciated that alternative components for reducing mechanical friction can be used, e.g. the redraw sleeve may be supported by a linear bearing comprising ball bearings or a set of rollers. 
     The redraw sleeve alignment mechanism  103  may also be used in a modular can bodymaker. For example, the redraw sleeve alignment mechanism  13  may form part of a toolpack module  101  that can be removed from the can bodymaker. Such a toolpack module  101  can be attached to an alignment bed to allow alignment of the redraw sleeve module  13  with respect to the components housed within the toolpack module (such as the redraw die). Once the toolpack module  101  has been aligned, it can be replaced precisely in its original position on the machine bed of the can bodymaker. 
       FIG. 6  is a flow diagram illustrating a method of setting up the bodymaker  1  of  FIG. 1 . The first step of the method  51  is to fix the cup locator  17  to the redraw sleeve alignment mechanism  103  and then, with the redraw sleeve  7  and ram  2  fully retracted, to fix S 2  the redraw sleeve alignment mechanism  103  with attached cup locator  17  into the bodymaker  1 . Using the rods  19   a - c , the cup locator  17  is adjusted S 3  radially with respect to the redraw die  11  attached to the bodymaker  1 . Next, the redraw sleeve  7  is separated from the redraw carriage, e.g. by separating the magnetic couplings, and advanced into and through the redraw sleeve module S 4 . The rods  23   a - d  are then adjusted S 5  to align the redraw sleeve  7  radially with respect to the redraw die, whereupon the redraw sleeve is pushed into and through the redraw bearing. Alternatively, the redraw sleeve  7  may be advanced into and through the redraw sleeve module  13  after the redraw sleeve module  13  has been aligned with respect to the redraw die. The redraw sleeve  7  and the redraw carriage  8  are then re-coupled S 6 . It will be appreciated that this recoupling is made possible because it allows for relative radial movement of the redraw sleeve  7  and the redraw carriage  8 . 
     It will be understood by the person of skill in the art that various modifications may be made to the above described embodiments without departing from the scope of the present invention. 
     
       
         
           
               
            
               
                   
               
               
                 Table of components referred to in the description 
               
            
           
           
               
               
               
            
               
                   
                 Component 
                 Reference numeral(s) 
               
               
                   
                   
               
               
                   
                 Can bodymaker 
                  1 
               
               
                   
                 Ram 
                  2 
               
               
                   
                 Redraw sleeve assembly 
                  3 
               
               
                   
                 Redraw sleeve alignment mechanism 
                 103  
               
               
                   
                 Redraw sleeve module housing 
                  3a 
               
               
                   
                 Bottom forming tool 
                  4 
               
               
                   
                 Can discharge turret 
                  5 
               
               
                   
                 Infeed mechanism 
                  6 
               
               
                   
                 Redraw sleeve 
                  7 
               
               
                   
                 Redraw carriage 
                  8 
               
               
                   
                 Push rods 
                 9, 10 
               
               
                   
                 Redraw die 
                 11 
               
               
                   
                 Toolpack module 
                 101  
               
               
                   
                 Bodymaker cradle 
                 12 
               
               
                   
                 Redraw sleeve module 
                 13 
               
               
                   
                 Cylindrical bearing frame 
                  13a 
               
               
                   
                 Bracket 
                 14 
               
               
                   
                 Opposed flanges 
                 15, 15a 
               
               
                   
                 Magnets 
                 16 
               
               
                   
                 Cup locator 
                 17 
               
               
                   
                 Eccentric cams 
                   18a-c 
               
               
                   
                 Sguare rods 
                   19a-c 
               
               
                   
                 Bridge 
                 20 
               
               
                   
                 Passage 
                 21 
               
               
                   
                 Bearing support cylinder 
                 22 
               
               
                   
                 Bearing support cylinder body 
                  22a 
               
               
                   
                 Bearing support cylinder flange 
                  22b 
               
               
                   
                 Rods 
                   23a-d 
               
               
                   
                 Lip seals 
                   25a, b 
               
               
                   
                 Ring 
                 26 
               
               
                   
                 Bearings 
                   26a, b 
               
               
                   
                 Circumferential groove 
                 27 
               
               
                   
                 Lubricating device 
                 28 
               
               
                   
                 Capped reservoir 
                 29 
               
               
                   
                 Dispensing end 
                 30 
               
               
                   
                 Eccentric cams 
                   31a-d