Patent Publication Number: US-2021187688-A1

Title: Pressure shoe

Description:
The present invention relates to a pressure shoe for pressing finish band onto surfaces of a rotating workpiece, with a carrier, with a radial press-on surface for pressing finish band onto a circumferential surface of the workpiece, and with axial press-on surfaces for pressing the finish band onto axially aligned cheek surfaces of the workpiece that border the circumferential surface, wherein at least one axial press-on surface is formed by at least one axial press-on element, and the at least one axial press-on element can be at least sectionally moved in an axial direction relative to the carrier. 
     A pressure shoe with the aforementioned features is known from EP 0 802 017 B1. Such a pressure shoe is intended for use in pressing finish band not just against a circumferential surface of a pin bearing of a crankshaft, but also against the cheek surfaces, which border the circumferential surface of the pin bearing in an axial direction of the workpiece. Since the pressure shoe and the shaft-like workpiece perform an oscillating movement relative to each other in an axial direction of the shaft-like workpiece during finishing operations, EP 0 802 017 B1 proposes that the carrier of the pressure shoe incorporate adjusting devices that follow the oscillating movements. 
     Despite the in particular pneumatically and hydraulically activated adjusting devices, it cannot be ensured that the finish band will be uniformly pressed against the opposing cheek surfaces at all times, so that a similar removal takes place both on the cheek surfaces and on the circumferential surface. In addition, one embodiment proposes a mechanical adjusting element, in which the axial press-on elements designated as sliding elements are moved in the axial direction of the workpiece due to a spring coupling, making it impossible to specifically adjust the axial press-on forces on the cheek surfaces. 
     Therefore, the object of the present invention is to eliminate the disadvantages described in relation to prior art, and in particular to indicate a pressure shoe which can be used to process the circumferential surface and the cheek surfaces bordering the circumferential surface with a similar removal. 
     The object is achieved by a pressure shoe with the features of a respective independent claim. Advantageous further developments of the pressure shoe are indicated in the dependent claims and in the specification, wherein individual features of the advantageous further developments can also be combined with each other as desired in a technically sensible manner. 
     In particular, the object is achieved by a pressure shoe with the features mentioned at the outset, in which the pressure shoe comprises a holder for fastening the pressure shoe to a processing machine, wherein the carrier is mounted on the holder so that it can move in the axial direction. 
     The basic idea underlying the invention thus provides that the movement of the carrier and the holder in an axial direction be at least partially decoupled during a finishing operation, so that the holder can perform an oscillatory movement relative to the workpiece, while the carrier, and hence the press-on elements that press the finish band against the surfaces, do not perform any oscillating movement relative to the workpiece. This makes it possible to ensure that the axial press-on surfaces are pressed against the cheek surfaces with nearly a constant force during finishing operations. As a consequence, the press-on elements themselves do not perform any oscillating movements relative to the carrier. In this way, a similar removal rate can be achieved on the circumferential surface and the cheek surfaces. 
     In order to realize a relative movability between the holder and the carrier in an axial direction, at least one linear bearing can be formed between the holder and the carrier. The linear bearing is formed in particular by an open guide bushing and an axis, which in particular is movably mounted in the bushing by means of a ball bearing. The axis is preferably formed on the holder, while the bushing is formed on the carrier. 
     However, it can also be provided that the carrier be fastenable to at least one coupling element in a quickly detachable manner, wherein the at least one linear bearing is arranged between the coupling element and the holder. In this way, the carrier with the press-on elements can be easily replaced, without components for the linear bearing having to be provided on the carrier. As a consequence, the pressure shoe can be easily adjusted to different radii of the circumferential surfaces by replacing the carrier and the press-on elements held thereon. 
     In a preferred embodiment, the holder is U-shaped in design, wherein a linear bearing is arranged in both legs of the holder with a U-shaped design. 
     The object is also achieved by a pressure shoe with the features mentioned at the outset, in which the axial press-on element is coupled with the carrier in an axial direction in such a way that a force can be made to act on the at least one axial press-on element in an axial direction by pressing the radial press-on surface of the pressure shoe onto the circumferential surface of the workpiece. The width of the pressure shoe viewed in the axial direction of the workpiece while being provided towards the circumferential surface of the workpiece is thus smaller than the distance between the opposing cheek surfaces of the workpiece. Pressing the pressure shoe onto the circumferential surface spreads the pressure shoe, so that its width increases, as a result of which the axial press-on surfaces of the pressure shoe are pressed against the check surfaces of the workpiece. 
     The axial press-on element movably mounted in particular as a whole on the carrier is thus secured to the carrier in such a way that the radial press-on force (which is always present during finishing operations for pressing the finish band onto the circumferential surfaces of the workpiece) is at least partially converted into an axial press-on force for additionally pressing the finish band onto the cheek surfaces of the workpiece. In particular, such a possibly indirect coupling between the axial press-on element and carrier takes place mechanically, for example via wedge surfaces between the axial press-on element and the carrier. 
     As a consequence, no additional drive is required for generating the axial press-on force. In this aspect of the invention, it is thus provided that there be a diversion of force, which transfers the press-on force acting on the circumferential surface in particular in a radial direction to a force acting on the axial press-on elements in an axial direction. 
     In particular, it is provided that two axial press-on elements acting in opposite directions be provided, which are acted upon with the same force in an axial direction, so that the axial press-on elements are pressed onto the two cheek surfaces with an identical force. 
     The radial press-on surface is preferably at least sectionally formed by at least one radial press-on element, wherein the radial press-on element is mounted so that it can be moved in a radial direction to the carrier in such a way that the radial press-on element can be moved toward the carrier by pressing the pressure shoe onto the circumferential surface of the workpiece, wherein the radial press-on element is coupled with the at least one axial press-on element in such a way that the at least one axial press-on element can be acted upon with a force in the axial direction by pressing the radial press-on element onto the circumferential surface of the workpiece. 
     Acting on the radial press-on elements in the direction of the carrier thus triggers a movement of the radial press-on element in a radial direction, which is converted into a movement of the axial press-on element in an axial direction. 
     The at least one radial press-on element is preferably spring preloaded in the direction of the circumferential surface of the workpiece (in a radial direction). In addition, in particular the axial press-on element is spring preloaded opposite its (axial) deployment movement in an axial direction, so that when the pressure shoe is lifted from the circumferential surface of the workpiece, the press-on elements automatically return to their original position. 
     In particular, the at least one radial press-on element is mechanically coupled with the at least one axial press-on element, wherein the coupling takes place in particular via wedge surfaces formed on the press-on elements. 
     In a preferred embodiment, at least three radial press-on elements are provided, which each interact with two axial press-on elements that can be acted upon by a force in an opposite direction. 
     It is also preferred that the press-on surface, meaning the radial press-on surface and/or the axial press-on surface, be formed at least sectionally by a material that can be deformed during finishing operations, so that the press-on surfaces at least partially adjust to the surfaces to be finished surfaces, and thus do not themselves prescribe the shape of the surfaces to be processed. In this way, only the surface quality is improved, without significantly changing the form of the surface itself. 
     The carrier of the pressure shoe is the element on which the press-on elements are in particular movably mounted. The press-on elements in turn themselves form the press-on surfaces, wherein in particular the axial press-on element can form both an axial press-on surface and a section of the radial press-on surface. 
     In order to realize the invention, it would be sufficient to provide only one axial press-on element, which can be moved in precisely one direction to the carrier, since the other press-on surface possibly formed by the carrier would be pressed against the opposing check surface during finishing operations. However, two press-on elements movably mounted on the carrier are preferably provided. 
     The directional indications involving the radial and axial directions relate to the workpiece to be processed. In particular, the pressure shoe is used to process surfaces of shaft-like workpiece, for example of a crankshaft. The axial direction is thus parallel to the main axis of symmetry of the workpiece to be processed. In particular, the circumferential surface to be processed is ring-shaped, so that the radial press-on surface is also partially ring-shaped in design. 
     The term radial direction relates to this circumferential—or press-on—surface, and hence is aligned orthogonally on the press-on surface. 
     In particular, the pressure shoe is used in a device for finishing surfaces of shaft-like workpieces, wherein the device comprises a workpiece mount, a rotation drive for the workpiece mount, a press-on device for pressing a pressure shoe onto a circumferential surface of the workpiece, an oscillation drive for generating an oscillating relative movement between the workpiece mount and the press-on device in an axial direction of the workpiece, and a finish band to be arranged between the pressure shoe and surface of the workpiece to be processed. 
     In particular, the invention relates to the finishing of such shaft-like workpieces, which in particular ring-shaped circumferential surface to be finished is bordered at least sectionally in an axial direction by opposing cheek surfaces, which are in turn aligned in an axial direction. Such cheek surfaces are also referred to as collar surfaces. 
     In particular, the press-on device comprises at least two press-on arms, to which a respective pressure shoe is fastened, wherein only one pressure shoe is designed according to the invention. In particular, the other pressure shoe is a conventional pressure shoe. As a result of this type of structural design, the conventional pressure shoe can perform an oscillating movement relative to the workpiece, and thus shape the circumferential surface, while the press-on surfaces of the pressure shoe according to the invention do not perform a movement relative to the workpiece, and thus preferably without shaping increase the surface quality of both the circumferential surfaces and the cheek surfaces, since the press-on surfaces of this pressure shoe can be decoupled from the oscillating movement. 
    
    
     
       The invention as well as the technical background will be exemplarily described below based on the figures. Shown schematically on: 
         FIG. 1 : is a perspective view of two pressure shoes, 
         FIG. 2 : is the pressure shoe according to the invention, 
         FIG. 3 : is a cross section through the pressure shoe according to the invention, and 
         FIG. 4 : is a longitudinal section through the pressure shoe according to the invention. 
     
    
    
     Shown on  FIG. 1  is a conventional pressure shoe  1  (top) and a pressure shoe  1  according to the invention (bottom). 
     The pressure shoe  1  shown at the top of  FIG. 1  is fastened to a press-on arm of a finishing device, and is pressed against a circumferential surface of a workpiece by the press-on arm. During the finishing operation, the pressure shoe  1  performs an oscillating movement in an axial direction relative to the workpiece (not shown). During the finishing operation, a finish band is arranged between the pressure shoe  1  and the circumferential surface of the workpiece to be processed, and is pressed against the circumferential surface of the workpiece to be processed by the pressure shoe  1 . 
     In addition to a radial press-on surface  3 , the pressure shoe  1  according to the invention shown at the bottom of  FIG. 1  also has axial press-on surfaces  4 , which press the finish band against the cheek surfaces of the workpiece axially bordering the circumferential surface. The press-on surfaces  3 ,  4  of the pressure shoe  1  shown at the bottom of  FIG. 1  are decoupled from the oscillation movement between the press-on arm and workpiece, and thus do not perform any axial movement relative to the surfaces of the workpiece to be processed. 
     The pressure shoe  1  has a carrier  2 , on which three radial press-on elements  7  and two axial press-on elements  5  are movably mounted. As evident in particular from a combined review of  FIGS. 2 and 3 , the radial press-on elements  7  comprise part of the radial press-on surface  3 , while the two axial press-on elements  5  each comprise part of the radial press-on surface  3  and one respective axial press-on surface  4 . 
     For purposes of decoupling from the oscillating relative movement between the press-on arm and workpiece, the carrier  2  is mounted on a holder  6  via two linear bearings  10  so it can move in an axial direction  9 . The carrier  2 , and hence also the press-on elements  5 ,  7 , can thus be moved in the axial direction  9  relative to the holder  6 . As a consequence, the press-on surfaces  3 ,  4  can remain stationary relative to the workpiece, while the press-on arm and the workpiece perform an oscillating movement relative to each other in the axial direction  9 . 
     As evident from  FIG. 3 , the radial press-on elements  7  are coupled together with the axial press-on elements  5  by wedge surfaces  11 . While pressing the pressure shoe  1 , the radial press-on element  7  is moved in a radial direction  8  toward the carrier  2 , as a result of which the axial press-on elements  5  are moved in the axial direction  9  in opposite directions due to the wedge surfaces  11 . As a consequence, the axial press-on surfaces  4  press the finish band (not shown) against cheek surfaces of the workpiece to be processed. The press-on force acting in the radial direction  8  is thus converted into a press-on force acting in the axial direction  9  for the axial press-on surfaces  4 . 
     For purposes of finishing, the pressure shoe  1  according to the invention is pressed against a circumferential surface of an shaft-like workpiece arranged between two cheek surfaces, wherein a press-on force is also generated on the cheek surfaces. Since the carrier  2  is mounted so that it can move in an axial direction relative to the holder  6 , the press-on surfaces  3 ,  4  are decoupled from the axial oscillating movement that takes place between the workpiece and the holder  6 . 
     The two axial press-on elements  5  are coupled together via restoring springs  12 , which preload the axial press-on elements  5  toward each other. Also provided are restoring springs  12 , which each preload the radial press-on elements  7  away from the carrier  2 . The restoring springs  12  automatically return the press-on elements  5 ,  7  into their original position relative to the carrier  2  when the pressure shoe  1  is lifted from the workpiece. As a consequence, this ensures in particular that the axial press-on elements  5  no longer exert any press-on forces on the cheek surfaces when the pressure shoe  1  is removed from the workpiece. 
     REFERENCE LIST 
       1  Pressure shoe 
       2  Carrier 
       3  Radial press-on surface 
       4  Axial press-on surface 
       5  Axial press-on element 
       6  Holder 
       7  Radial press-on element 
       8  Radial direction 
       9  Axial direction 
       10  Linear bearing 
       11  Wedge surface 
       12  Restoring spring