Patent Publication Number: US-11378149-B2

Title: Method of manufacturing a damper tube

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and is a divisional application of U.S. patent application Ser. No. 16/045,271, filed on Jul. 25, 2018, now U.S. Pat. No. 10,920,847, issued Feb. 16, 2021, which is hereby incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a method of manufacturing a damper tube. More particularly, the present disclosure relates to a method for manufacturing the damper tube for a suspension system. 
     BACKGROUND 
     A damper tube is generally used as a base assembly for a suspension system, such as a shock absorber. The damper tube may be manufactured using one or more components, joints, and/or manufacturing processes. As such, the manufacturing of the damper tube may be complex, time intensive, labor intensive, and expensive. Also, a material of construction used for the damper assembly may add considerable weight to the damper tube. Further, a change in a design of the damper tube may demand a change in the manufacturing process. To achieve this, alternative manufacturing process may have to be employed based on the new design. 
     In some situations, automated manufacturing processes may be employed which may relieve the operator and increase throughput, thus, improving production rate and production costs. Moreover, a material of construction and specific techniques used to process the material may significantly govern the production costs. Therefore, both the material and the processes involved may need to be considered for reducing the complexity and costs. Conventional methods of manufacturing the damper tube may include multiple components and/or manufacturing steps increasing complexity of the manufacturing process, increasing investment cost, reducing logistic flow, and making the damper tube heavy and expensive. Hence, there is a need for an improved method of manufacturing the damper tube to reduce complexity, weight, and costs. 
     Given description covers one or more above mentioned problems and discloses a method and a system to solve the problems. 
     SUMMARY 
     In an aspect of the present disclosure, a method of manufacturing a damper tube is provided. The method includes providing a tube having a first end and a second end opposite to the first end. The method includes providing a reinforcing insert, at least partly, within the first end of the tube. The method includes flattening a portion of the first end of the tube. The method also includes bending at least one of the reinforcing insert and the flattened portion of the first end of the tube into a loop. The method further includes connecting an edge of the loop to the tube. 
     Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIGS. 1A and 1B  illustrate cross sectional views of exemplary tubes, according to an aspect of the present disclosure; 
         FIGS. 2A and 2B  illustrate cross sectional views of exemplary reinforcing inserts disposed within the exemplary tubes, according to an aspect of the present disclosure; 
         FIGS. 3A, 3B, 3C, 3D, and 3E  illustrate different steps of flattening the exemplary tube, according to an aspect of the present disclosure; 
         FIGS. 4A, 4B, and 4C  illustrate different steps of bending the exemplary reinforcing insert and the exemplary tube, according to an aspect of the present disclosure; 
         FIGS. 5A, 5B, 5C, 5D and 5E  illustrate cross sectional views of exemplary damper tubes, according to an aspect of the present disclosure; 
         FIG. 6  illustrates a flowchart of a method of manufacturing the damper tube, according to an aspect of the present disclosure; 
         FIG. 7  illustrates a flowchart of another method of manufacturing the damper tube, according to another aspect of the present disclosure; and 
         FIGS. 8A, 8B, 8C and 8D  illustrate different steps of flattening the exemplary tube, according to another aspect of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Wherever possible, the same reference numbers will be used throughout the drawings to refer to same or like parts. The present disclosure relates to a method of manufacturing a damper tube  502 ,  508  (shown in  FIGS. 5A, 5B, 5C, 5D and 5E ). The damper tube  502 ,  508  may be a portion of a base or strut assembly (not shown) of a shock absorber (not shown) used in a suspension system (not shown). The suspension system may be employed for shock dampening in various applications, such as automotive, aviation, aerospace, heavy machinery, marine, transportation, industrial, and the like. The damper tube  502 ,  508  may be adapted to enclose one or more components of the shock absorber, such as a piston, a volume of a working fluid, seals, and the like. 
     Referring to  FIG. 1A , a cross sectional view of an exemplary tube  102  is illustrated. The tube  102  has a substantially hollow and elongated configuration defining a central axis X-X′. The tube  102  includes a first end  104  and a second end  106 . The second end  106  is opposite the first end  104 . Also, in the illustrated embodiment, the tube  102  has a varying thickness along a length thereof. More specifically, the tube  102  has a first thickness “T 1 ” at the first end  104  and a second thickness “T 2 ” at the second end  106 . 
     In the illustrated embodiment, the first thickness “T 1 ” is greater than the second thickness “T 2 ”. In other embodiments, the tube  102  may include multiple thicknesses along the length thereof. In other embodiments, as shown in  FIG. 1B , the tube  108  may have a constant thickness “T” along the length between the first end  110  and the second end  112  thereof. The tube  102 ,  108  may be made of a material, such as a metal, an alloy, and the like. The method of manufacturing the damper tube  502  will be now explained with reference to the tube  108  having constant thickness “T” for the purpose of clarity and explanation. It should be noted that, in other embodiments, the damper tube  508  may be manufactured using the tube  102  with the varying thickness without limiting the scope of the disclosure. 
     Referring to  FIG. 2A , a reinforcing insert  202  is provided, at least partly, within the first end  104  of the tube  102 . In the illustrated embodiment, the reinforcing insert  202  has a substantially planar shape. Accordingly, the reinforcing insert  202  may include a metal strip, a portion of sheet metal, and the like. In other embodiments, as shown in  FIG. 2B , the reinforcing insert  204  may have a substantially cylindrical shape. In the illustrated embodiment, the reinforcing insert  204  has a substantially hollow, tubular shape. In other embodiments, the reinforcing insert  204  may have a substantially solid, rod like shape. The reinforcing insert  202 ,  204  may be made of a reinforcing material, such as a metal, an alloy, and the like. The method of manufacturing the damper tube  502  will be further explained with reference to the reinforcing insert  202  having the planar shape for the purpose of clarity and explanation. It should be noted that, in other embodiments, the damper tube  502  may be manufactured using the reinforcing insert  204  having the cylindrical shape without limiting the scope of the disclosure. 
     Referring to  FIGS. 3A and 3B , the first end  110  of the tube  108  having the reinforcing insert  202  is flattened. More specifically, as shown in  FIG. 3A , the first end  110  of the tube  108  along with the reinforcing insert  202  is placed between a flattening die  302  and a flattening press  304 . The flattening die  302  and the flattening press  304  may be configured based on the thickness and a diameter of the tube  108  and/or of the reinforcing insert  202 . Further, as shown in  FIG. 3B , the flattening press  304  may exert pressure on the first end  110  of the tube  108  to flatten a portion  306  of the first end  110  of the tube  108 , such that the tube  108  contacts the reinforcing insert  202 . As such, the reinforcing insert  202  is sandwiched between the flattened portion  306  of the first end  110  of the tube  108 . 
     In the illustrated embodiment, the first end  110  of the tube  108  is flattened in a manner, such that the flattened portion  306  is disposed at an offset “F” with respect to the central axis X-X′ of the tube  108 . In other embodiments, as shown in  FIG. 3C , the first end  110  of the tube  108  may be flattened in a manner, such that the flattened portion  306  is aligned with respect to the central axis X-X′ of the tube  108 . In some embodiments, when the reinforcing insert  204  may have the cylindrical shape as described in  FIG. 2B , the reinforcing insert  204  may be flattened along with the first end  110  of the tube  108 . 
     More specifically, as shown in  FIG. 3D , the first end  110  of the tube  108  along with the reinforcing insert  204  is placed between the flattening die  302  and the flattening press  304 . Further, as shown in  FIG. 3E , the flattening press  304  may exert pressure on the first end  110  of the tube  108  to flatten the portion  306  of the first end  110  of the tube  108  along with the reinforcing insert  204 . As such, the reinforcing insert  204  is flattened and sandwiched between the flattened portion  306  of the first end  110  of the tube  108 . 
     It should be noted that, in some embodiments, an additional trimming process (not shown) may be employed using a dedicated set of dies and/or tools (not shown) in order to trim and/or shape one or more end corners and/or an end boundary of the flattened portion  306  of the tube  108 . In such a situation, the trimmed portion of the flattened portion  306  of the tube  108  may be welded to provide sealing and corrosion resistance to the flattened portion  306  of the tube  108 . In some embodiments, a thickness of the flattened portion  306  of the tube  108  may be increased prior to flattening using known manufacturing processes. Also, it should be noted that, in some embodiments, as shown in  FIGS. 8A to 8D , the portion  306  of the first end  110  of the tube  108  may be partially flattened without the reinforcing insert  202 , such that the reinforcing insert  202  may be inserted later in the partially flattened portion  306 . The manufacturing process will be explained later in more detail with reference to  FIGS. 8A and 8D . 
     Referring to  FIGS. 4A to 4C , the reinforcing insert  202  and the flattened portion  306  of the tube  108  are bent into a loop  402 . More specifically, as shown in  FIGS. 4A and 4B , a first tool  404  and a first die  406  are provided in contact with the reinforcing insert  202  and the flattened portion  306  of the first end  110  of the tube  108 . The first tool  404  and the first die  406  are adapted to partly bend the reinforcing insert  202  and the flattened portion  306  of the tube  108 . The first tool  404  may be a punch tool, such as a gooseneck punch or any other tool adapted to bend the reinforcing insert  202  and the flattened portion  306  of the tube  108 . It should be noted that, in some embodiments, the first tool  404  and the first die  406  shown in each of the  FIGS. 4A and 4B  may include varying configurations in order to enable progressive bending of the reinforcing insert  202  and the flattened portion  306  of the tube  108 . 
     Further, as shown in  FIG. 4C , the first tool  404  and the first die  406  are replaced with a second tool  408 , a curling press  410 , and a curling die  412 . More specifically, the second tool  408 , the curling press  410 , and the curling die  412  are provided in contact with the partly bent reinforcing insert  202  and the flattened portion  306  of the tube  108  of  FIG. 4B . The second tool  408 , the curling press  410 , and the curling die  412  are adapted to bend the partly bent reinforcing insert  202  and the flattened portion  306  of the first end  110  of the tube  108  into the loop  402 . 
     The second tool  408  may be a curling tool or any other tool adapted to provide support to the flattened portion  306  of the tube  108  during curling of the reinforcing insert  202  and the flattened portion  306  of the tube  108  into the loop  402 . In some embodiments, the second tool  408  may be a bushing (not shown) used in the shock absorber. The bushing may provide a stiff connection between a vehicle chassis and the shock absorber. In a situation when the bushing may include an outer sleeve (not shown), such as a metallic rim, the bushing may provide reinforcement and support to the flattened portion  306  of the tube  108  during the curling process. 
     Further, the second tool  408  may be removed from the loop  402  to complete the bending process. It should be noted that the tools, the presses, the dies, and the bending process, described herein with reference to  FIGS. 4A to 4C  are merely exemplary and may vary based on application requirements. For example, in some embodiments, the bending process may be completed in a single step by using a single set of a tool and a die. In other embodiments, the bending process may be completed in multiple steps by using multiple sets of tools and dies, such as by forming multiple small bends adjacent to one another in the flattened portion  306  of the tube  108  by pushing the flattened portion  306  of the tube  108  against the first tool  404  or vice versa. Also, it should be noted that, although the bending and curling process is described herein with reference to the reinforcing insert  202 , the reinforcing insert  204  and the flattened portion  306  of the tube  108  may be bent and curled into the loop  402  in a manner similar to that described with reference to  FIGS. 4A to 4C . 
     It should be noted that, in the illustrated embodiment, each of the flattening die  302 , the flattening press  304 , the first die  406 , the curling press  410 , and the curling die  412  is exemplarily shown in a substantially vertical orientation. In other embodiments, one or more of the flattening die  302 , the flattening press  304 , the first die  406 , the curling press  410 , and the curling die  412  may be oriented in any other manner, such as inclined or horizontally. Also, the flattening die  302  and the flattening press  304  may be configured in a manner to perform on-center or off-center flattening of the portion  306  of the tube  108  with respect to the central axis X-X′, based on application requirements. 
     In some embodiments, the reinforcing insert  202  and the flattened portion  306  of the tube  108  may be heated prior to or during the bending process. The heating of the reinforcing insert  202  and the flattened portion  306  of the tube  108  may limit material failure due to straining and/or plastic deformation and may improve formability. Also, the heating of the reinforcing insert  202  and the flattened portion  306  of the tube  108  when employed in combination with the second tool  408  during the bending process may limit spring back effect in the loop  402 . The heat may be applied using a heating method, such as a gas torch heating, laser assisted heating and bending, induction heating, furnace heating, infrared lamp heating, and the like. 
     In some embodiments, the spring back effect in the loop  402  may be limited by using spring back compensation techniques, such as forming, measuring, and compensation. In some embodiments, the spring back effect in the loop  402  may be limited by using laser assisted in-process measuring of a bending angle in order to allow in-process monitoring and correction of the bending angle. Also, the reinforcing insert  202  improves strength and stiffness of the loop  402  under dynamic and/or static loading conditions. In some embodiments, the variable thickness of the tube  102  (as shown in  FIG. 1B ) along with the reinforcing insert  202  may add structural rigidity to the loop  402 . 
     Referring to  FIGS. 5A, 5B, 5C, 5D and 5E , an edge  504  of the loop  402  is connected to the tube  108 . More specifically, the edge  504  of the loop  402  is connected to the tube  108  by a weld  506  in order to seal the edge  504 , limit straightening of the loop  402 , and/or provide structural rigidity to the loop  402 . It should be noted that a length of the flattened portion  306  and/or a length of the reinforcing insert  202  may be approximately equal to a circumference of the loop  402 . In some embodiments, as shown in  FIG. 5A , a center “C” of the loop  402  may be aligned with respect to the central axis X-X′ of the damper tube  502 . In some embodiments, as shown in  FIG. 5B , the center “C” of the loop  402  may be disposed at an offset “F” with respect to the central axis X-X′ of the damper tube  502 . Such a configuration of the loop  402  with respect to the central axis X-X′ may provide increased stiffness and load bearing capacity of the loop  402  and/or the damper tube  502 . 
     Referring to  FIG. 5C , an embodiment of the damper tube  508  formed with the tube  102  having the varying thickness (as shown in  FIG. 1A ) is illustrated. The damper tube  508  includes a configuration and method of manufacturing substantially similar to that of the damper tube  502 . It should be noted that, in the illustrated embodiment, a substantial portion of the tube  102  having the first thickness “T 1 ” is bent into the loop  402 . In other embodiments, a portion of the tube  102  bent into the loop  402  may vary based on application requirements. 
     Referring to  FIG. 5D , in some embodiments, each of the flattened portion  306  of the tube  108  and the center “C” of the loop  402  may be aligned with respect to the central axis X-X′ of the damper tube  502 . Referring to  FIG. 5E , in some embodiments, the insert  202  may include a length substantially shorter than the circumference of the loop  402 . In such a situation, the insert  202  may be provided in a region of maximum stress concentration. Further, the insert  202  may not be bent. Further, in some embodiments, inner surfaces  510 ,  512  of the loop  402  beyond the insert  202  may contact each other, as shown. Additionally, in some embodiments, the weld  506  may couple both the edge  504  and the insert  202  with the loop  402 . In some embodiments, one or more notches  514  may be provided on the inner surface  516  of the damper tube  108 . The notch  514  may be adapted to support a base valve (not shown) of the shock absorber. 
     Referring to  FIG. 6 , a flowchart of a method  600  of manufacturing the damper tube  502  is illustrated. At step  602 , the tube  108  having the first end  110  and the second end  112  opposite to the first end  110  is provided, as described with reference to  FIG. 1B . In some embodiments, as described with reference to  FIG. 1A , the tube  102  may include a first thickness “T 1 ” of the first end  104  of the tube  102  different from the second thickness “T 2 ” of the second end  106  of the tube  102 . At step  604 , the reinforcing insert  202  is provided, at least partly, within the first end  110  of the tube  108 , as described with reference to  FIGS. 2A and 2B . 
     In some embodiments, as described with reference to  FIG. 2A , the reinforcing insert  202  has the substantially planar shape such that the first end  110  of the tube  108  is flattened to contact the reinforcing insert  202 . In some embodiments, as described with reference to  FIG. 2B , the reinforcing insert  204  has the substantially cylindrical shape such that the reinforcing insert  204  is flattened along with the first end  110  of the tube  108 . At step  606 , the portion of the first end  110  of the tube  108  is flattened, as described with reference to  FIGS. 3A to 3E . 
     At step  608 , at least one of the reinforcing insert  202  and the flattened portion  306  of the first end  110  of the tube  108  is bent into the loop  402 , as described with reference to  FIGS. 4A to 4C . More specifically, the first tool  404  is provided in contact with the reinforcing insert  202  and the flattened portion  306  of the first end  110  of the tube  108 . The first tool  404  is adapted to at least partly bend the reinforcing insert  202  and the flattened portion  306  of the first end  110  of the tube  108 . Further, the first tool  404  is replaced with the second tool  408  in contact with the partly bent reinforcing insert  202  and the flattened portion  306  of the first end  110  of the tube  108 . The second tool  408  is adapted to bend the partly bent reinforcing insert  202  and the flattened portion  306  of the first end  110  of the tube  108  into the loop  402 . 
     Further, the second tool  408  is removed from the loop  402  to complete the curling process. In some embodiments, the reinforcing insert  202  and the flattened portion  306  of the first end  110  of the tube  108  may be heated during the bending and/or curling process. At step  610 , the edge  504  of the loop  402  is connected to the tube  108  by the weld  506 , as described with reference to  FIGS. 5A, 5B, 5C, 5D and 5E . In some embodiments, the center “C” of the loop  402  is aligned with respect to the central axis X-X′ of the tube  108 , as described with reference to  FIGS. 5A, 5C, 5D and 5E . In some embodiments, the center “C” of the loop  402  is disposed at the offset “F” with respect to the central axis X-X′ of the tube  108 , as described with reference to  FIG. 5B . 
     Referring to  FIG. 7 , an alternate method  700  of manufacturing the damper tube  502  is illustrated. The method  700  will now be explained with combined reference to  FIGS. 1 to 8 . At step  702 , the tube  108  is provided having the first end  110  and the second end  112  opposite to the first end  110 , as described with reference to  FIGS. 1A and 1B . At step  704 , and referring to  FIG. 8A , a mandrel or a spacer tool  802  is provided, at least partly, within the first end  110  of the tube  108 . The spacer tool  802  may be inserted from the first end  110  or the second end  112  of the tube  108 . In the illustrated embodiment, the spacer tool  802  has a substantially planar shape. In other embodiments, the spacer tool  802  may have a substantially cylindrical shape. Also, in some embodiments, a width of the spacer tool  802  may be equal to an inner diameter of the tube  108  prior to flattening of the tube  108 . Accordingly, the spacer tool  802  may include a metal strip, a portion of sheet metal, and the like. At step  706 , and referring to  FIG. 8B , the portion of the first end  110  of the tube  108  is flattened, as described with reference to  FIGS. 3A to 3E , such that the tube  108  contacts the spacer tool  802 . 
     At step  708 , and referring to  FIG. 8C , the spacer tool  802  is removed from the flattened portion  306  of the first end  110  of the tube  108 . At step  710 , and referring to  FIG. 8D , the reinforcing insert  202  is provided within the flattened portion  306  of the first end  110  of the tube  108 . The reinforcing insert  202  has the substantially planar shape, as described with reference to  FIG. 2A , such that the first end  110  of the tube  108  is flattened to contact the reinforcing insert  202 . In some embodiments, the flattened portion  306  of the first end  110  of the tube  108  may be re-flattened, such that the tube  108  contacts the reinforcing insert  202  and any clearance between the reinforcing insert  202  and the flattened portion  306  of the tube  108  is removed. 
     At step  712 , at least one of the reinforcing insert  202  and the flattened portion  306  of the first end  110  of the tube  108  are bent into the loop  402 , as described with reference to  FIGS. 4A to 4C . More specifically, the first tool  404  is provided in contact with the reinforcing insert  202  and the flattened portion  306  of the first end  110  of the tube  108 . The first tool  404  is adapted to at least partly bend the reinforcing insert  202  and the flattened portion  306  of the first end  110  of the tube  108 . Further, the first tool  404  is replaced with the second tool  408  in contact with the partly bent reinforcing insert  202  and the flattened portion  306  of the first end  110  of the tube  108 . 
     The second tool  408  is adapted to bend the partly bent reinforcing insert  202  and the flattened portion  306  of the first end  110  of the tube  108  into the loop  402 . Further, the second tool  408  is removed from the loop  402  to complete the curling process. In some embodiments, the reinforcing insert  202  and the flattened portion  306  of the first end  110  of the tube  108  may be heated during the bending and/or curling process. At step  714 , the edge  504  of the loop  402  is connected to the tube  108  by the weld  506 , as described with reference to  FIGS. 5A, 5B, 5C, 5D and 5E . 
     In some embodiments, one or more tools, dies, presses, and/or machines (not shown) having similar or dissimilar working capacities may be employed in a synchronized operational configuration in order to improve productivity. The synchronized operation of the machines may be controlled via Computer Numeric Control (CNC). Additionally, or optionally, an integrated automated tool changing system (not shown) having a library of various tooling may be used in tool changing operation. In some embodiments, different machines may be operated independently in order to improve flexibility of the process. In some embodiments, the complete process may be automated, such that multiple tubes may be processed using a single operation. Moreover, completion of multiple tasks such as tube end reduction/expansion, flattening (with or without trimming), and curling may be achieved using, for example, custom work benches having combined hydraulic units. 
     In such situations, a controller (not shown) may be employed in order to automate the process. The controller may be communicably coupled to the one or more machines. The controller may be a control unit configured to perform various functions of the process. In one embodiment, the controller may be a dedicated control unit configured to perform functions related to the process. In another embodiment, the controller may be a Machine Control Unit (MCU) associated with the one or more machines to perform functions related to the process. 
     The method  600 ,  700  provides a simple and effective process to flatten, bend, and curl the damper tube  502 ,  508  by limiting operational steps, process components, and multiple joints or welds. The limitation of the joint to the single weld  506  may improve corrosion resistance and durability of the damper tube  502 ,  508 . Also, in situations when the tube  102  with variable thickness may be used, an overall weight of the damper tube  508  may be substantially reduced while providing reinforcement at the loop  402 . As such, the method  600 ,  700  provides a simplified structure of the damper tube  502 ,  508  in order to reduce manufacturing and/or assembly complexity and costs. 
     While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof