Patent Publication Number: US-2023147582-A1

Title: Structure, image forming apparatus, method of producing structure

Description:
TECHNICAL FIELD 
     The present invention relates to a structure including a plurality of rectangular pipes joined together, an image forming apparatus including the structure, and a method of producing a structure. 
     BACKGROUND ART 
     An image forming apparatus includes a sheet feed portion, a printing portion, and a developer container. The image forming apparatus further includes a structure that houses and supports the sheet feed portion, the printing portion, and the developer container. 
     For example, the structure is known to include a plurality of rectangular pipes joined by welding (for example, see PTL 1). The structure with such a configuration has high strength. 
     CITATION LIST 
     Patent Literature 
     [PTL 1] Japanese Patent Application Publication No. 2000-138470 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     Usually, each of the rectangular pipes constituting the structure is cut out from a long base pipe to a desired length. In this case, it is difficult to increase the accuracy of the length of each rectangular pipe and the accuracy of the angles of the end faces relative to the side faces. 
     Accordingly, welding two rectangular pipes together with an end face of one of the pipes in contact with a side face of the other pipe makes it difficult to produce the structure with high dimensional accuracy. 
     An object of the present invention is to provide a structure including a plurality of rectangular pipes joined by welding and having high dimensional accuracy, an image forming apparatus including the structure, and a method of producing the structure. 
     Solution to the Problems 
     A structure according to an aspect of the present invention includes a plurality of rectangular pipes joined together. The plurality of rectangular pipes include a first rectangular pipe and a second rectangular pipe joined by welding. Two or three of four sides that constitute an end face of the first rectangular pipe are joint sides welded to a side face of the second rectangular pipe, whereas a rest of the four sides is a non-joint side separated from the side face of the second rectangular pipe by a gap. 
     An image forming apparatus according to another aspect of the present invention includes a sheet feed portion, a printing portion, and the above-described structure. The printing portion forms an image on a sheet supplied from the sheet feed portion. The structure houses and supports the sheet feed portion and the printing portion. 
     A method of producing a structure according to another aspect of the present invention is a method of producing the structure including a plurality of rectangular pipes joined together. The production method includes positioning a first rectangular pipe and a second rectangular pipe by placing the first rectangular pipe and the second rectangular pipe along a jig for positioning such that four sides constituting an end face of the first rectangular pipe face a side face of the second rectangular pipe with a gap therebetween. The production method further includes welding only some of the four sides that constitute the end face of the first rectangular pipe, the four sides facing the side face of the second rectangular pipe with the gap therebetween, to the side face of the second rectangular pipe. 
     Advantageous Effects of the Invention 
     According to the present invention, a structure including a plurality of rectangular pipes joined by welding and having high dimensional accuracy, an image forming apparatus including the structure, and a method of producing the structure can be provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a configuration diagram of an image forming apparatus including a structure according to an embodiment. 
         FIG.  2    is a perspective view of the structure according to the embodiment. 
         FIG.  3    is a perspective view of two rectangular pipes joined together in the structure according to the embodiment. 
         FIG.  4    is a side view of a joint part in the structure according to the embodiment. 
         FIG.  5    is a plan view of the joint part in the structure according to the embodiment. 
         FIG.  6    is a flowchart showing a procedure of a method of producing the structure according to the embodiment. 
         FIG.  7    shows a step of positioning the rectangular pipes in the method of producing the structure according to the embodiment. 
         FIG.  8    is a perspective view of two rectangular pipes positioned in the step of positioning the rectangular pipes in the method of producing the structure according to the embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The following describes an embodiment of the present invention with reference to the accompanying drawings. It should be noted that the following embodiment is an example of a specific embodiment of the present invention and should not limit the technical scope of the present invention. 
     [Configuration of Image Forming Apparatus  10 ] 
     A structure  6  according to an embodiment is adopted by an image forming apparatus  10 . As shown in  FIG.  1   , the image forming apparatus  10  includes a body unit  1  and an image reading unit  2 . 
     The body unit  1  includes sheet feed portions  30 , a sheet conveying device  3 , a printing portion  4 , one or more developer containers  5 , and the structure  6 . The image reading unit  2  is connected to an upper part of body unit  1 . The image reading unit  2  reads the images of document sheets. 
     The sheet feed portions  30  each house a plurality of sheets and feed the housed sheets one by one to a sheet conveyance path  300 . The sheet conveying device  3  includes a plurality of conveying roller pairs  31  that convey the sheets along the sheet conveyance path  300 . 
     The printing portion  4  forms images on the sheets supplied from the sheet feed portions  30  through the sheet conveying device  3 . In the example shown in  FIG.  1   , the printing portion  4  forms images on the sheets by an electrophotographic method. 
     The electrophotographic printing portion  4  includes a laser scanning unit  40 , one or more image creating devices  4   x , a transfer device  44 , and a fixing device  45 . 
     In the example shown in  FIG.  1   , the printing portion  4  is a color-image printing device of a tandem type. Accordingly, the printing portion  4  includes four image creating devices  4   x  that respectively correspond to four colors of toner. Furthermore, the image forming apparatus  10  includes four developer containers  5  that respectively correspond to the four image creating devices  4   x.    
     In each of the image creating devices  4   x , a drum-shaped photoconductor  41  rotates, a charging device  42  electrically charges the outer peripheral surface of the photoconductor  41 , the laser scanning unit  40  forms an electrostatic latent image on the outer peripheral surface of the photoconductor  41 , and a developing device  43  develops the electrostatic latent image as a toner image. 
     Furthermore, in the transfer device  44 , an intermediate transfer belt  440  rotates while being in contact with the four photoconductors  41 , four primary transfer devices  441  respectively corresponding to the four image creating devices  4   x  transfer the toner images to the intermediate transfer belt  440 , and a secondary transfer device  442  transfers the toner images on the intermediate transfer belt  440  to the sheets that are being conveyed on the sheet conveyance path  300 . 
     The fixing device  45  fixes the toner images on the sheets to the sheets by heating and pressurizing the toner images. The sheet conveying device  3  discharges the sheets on which images have been formed from the sheet conveyance path  300 . 
     The developer containers  5  supply toner to the corresponding developing devices  43  in the printing portion  4 . The toner is an example of developer. The printing portion  4  may form images on the sheets by an inkjet printing method or other methods. 
     The structure  6  houses and supports the sheet feed portions  30 , the sheet conveying device  3 , the printing portion  4 , and the developer containers  5 . The image reading unit  2  is connected to an upper part of structure  6 . The structure  6  includes a plurality of rectangular pipes  60  joined by welding (see  FIG.  2   ). 
     Usually, each of the rectangular pipes  60  constituting the structure  6  is cut out from a long base pipe to a desired length. In this case, it is difficult to increase the accuracy of the length of each rectangular pipe  60  and the accuracy of the angles of the end faces relative to the side faces. 
     Accordingly, welding two rectangular pipes  60  together with an end face of one of the pipes in contact with a side face of the other pipe makes it difficult to produce the structure  6  with high dimensional accuracy. 
     However, as described below, the plurality of rectangular pipes  60  constituting the structure  6  are joined such that the structure  6  has high dimensional accuracy as a whole even though the dimensional accuracy of the end faces of each rectangular pipe  60  is not high. 
     [Structure  6 ] 
     As shown in  FIG.  2   , the structure  6  includes the plurality of rectangular pipes  60  joined by welding. The structure  6  is a single-piece member into which the plurality of metal rectangular pipes  60  are joined by welding. 
     It is noted that, in the example shown in  FIG.  2   , a metal panel  8  is welded to the structure  6 . 
     In the description below, one of two rectangular pipes  60  in the structure  6  joined by welding is referred to as a first rectangular pipe  60   a , and the other is referred to as a second rectangular pipe  60   b  (see  FIG.  3   ). That is, the plurality of rectangular pipes  60  include the first rectangular pipe  60   a  and the second rectangular pipe  60   b  joined by welding. 
       FIG.  3    is a perspective view of the first rectangular pipe  60   a  and the second rectangular pipe  60   b .  FIG.  4    is a side view of a joint part of the first rectangular pipe  60   a  and the second rectangular pipe  60   b .  FIG.  5    is a plan view of the joint part of the first rectangular pipe  60   a  and the second rectangular pipe  60   b.    
     As shown in  FIGS.  3  to  5   , an end face  62  of the first rectangular pipe  60   a  is welded to a side face  63  of the second rectangular pipe  60   b.    
     As shown in  FIGS.  4  and  5   , two parallel sides of four sides that constitute the end face  62  of the first rectangular pipe  60   a  are joint sides  62   a  welded to the side face  63  of the second rectangular pipe  60   b.    
     That is, the joint sides  62   a  of the end face  62  of the first rectangular pipe  60   a  are joined to the side face  63  of the second rectangular pipe  60   b  by welds  61 . The welds  61  are portions where the first rectangular pipe  60   a  and the second rectangular pipe  60   b  are partially fused. 
     The remaining two of the four sides that constitute the end face  62  of the first rectangular pipe  60   a  are non-joint sides  62   b  separated from the side face of the second rectangular pipe by a gap  600 . It is noted that three of the four sides that constitute the end face  62  of the first rectangular pipe  60   a  may be the joint sides  62   a  and that the remaining one side may be the non-joint side  62   b.    
     The joint sides  62   a  of the end face  62  are welded to the side face  63  of the second rectangular pipe  60   b  with the end face  62  of the first rectangular pipe  60   a  facing the side face of the second rectangular pipe  60   b  with the gap  600  therebetween. 
     Accordingly, variations in the dimensions of the end face  62  of the first rectangular pipe  60   a  do not affect the positional relationship between the first rectangular pipe  60   a  and the second rectangular pipe  60   b.    
     [Method of Producing Structure  6 ] 
     Next, a procedure of a method of producing the structure  6  will be described with reference to a flowchart shown in  FIG.  6   . 
     In the following description, S 1 , S 2 , . . . are identification signs representing a plurality of steps of the method of producing the structure  6 . 
     &lt;Step  1 &gt; 
     First, in step S 1 , a jig  7  used to position the plurality of rectangular pipes  60  is prepared (see  FIGS.  7  and  8   ). 
     The jig  7  includes two first protrusions  71  corresponding to the first rectangular pipe  60   a  and two second protrusions  72  corresponding to the second rectangular pipe  60   b.    
     The first rectangular pipe  60   a  has first holes  64  serving as two positioning holes into which the first protrusions  71  of the jig  7  are inserted. Similarly, the second rectangular pipe  60   b  has second holes  65  serving as two positioning holes into which the second protrusions  72  of the jig  7  are inserted. 
     That is, the first rectangular pipe  60   a  has the two first holes  64  corresponding to the two first protrusions  71  of the jig  7 , and the second rectangular pipe  60   b  has the two second holes  65  corresponding to the two second protrusions  72  of the jig  7 . 
     &lt;Step S 2 &gt; 
     Next, in step S 2 , the plurality of rectangular pipes  60  are disposed along the jig  7  to be positioned in a predetermined positional relationship. 
     Step S 2  includes inserting the two first protrusions  71  of the jig  7  into the two first holes  64  of the first rectangular pipe  60   a  and inserting the two second protrusions  72  of the jig  7  into the two second holes  65  of the second rectangular pipe  60   b.    
     In the present embodiment, one of the two first holes  64  in the first rectangular pipe  60   a  is a circular hole  64   a , whereas the other is a long hole  64   b  extending in the longitudinal direction of the first rectangular pipe  60   a . Similarly, one of the two second holes  65  in the second rectangular pipe  60   b  is a circular hole  65   a , whereas the other is a long hole  65   b  extending in the longitudinal direction of the second rectangular pipe  60   b.    
     Fitting one of the two first protrusions  71  in the circular hole  64   a  causes the first rectangular pipe  60   a  to be positioned in the longitudinal direction, and fitting the other of the two first protrusions  71  in the long hole  64   b  causes the first rectangular pipe  60   a  to be positioned in the lateral direction. 
     Similarly, fitting one of the two second protrusions  72  in the circular hole  65   a  causes the second rectangular pipe  60   b  to be positioned in the longitudinal direction, and fitting the other of the two second protrusions  72  in the long hole  65   b  causes the second rectangular pipe  60   b  to be positioned in the lateral direction. 
     In step S 2 , the first rectangular pipe  60   a  and the second rectangular pipe  60   b  are positioned in the predetermined positional relationship with the four sides that constitute the end face  62  of the first rectangular pipe  60   a  facing the side face  63  of the second rectangular pipe  60   b  with the gap  600  therebetween. 
     It is noted that step S 2  is an example of positioning the first rectangular pipe  60   a  and the second rectangular pipe  60   b.    
     &lt;Step S 3 &gt; 
     Next, in step S 3 , only two of the four sides that constitute the end face  62  of the first rectangular pipe  60   a  facing the side face  63  of the second rectangular pipe  60   b  with the gap  600  therebetween are welded to the side face  63  of the second rectangular pipe  60   b.    
     In step S 3 , the welds  61  that join the joint sides  62   a , which are some of the four sides that constitute the end face  62  of the first rectangular pipe  60   a , and the side face  63  of the second rectangular pipe  60   b  are formed. 
     It is noted that, in step S 3 , only three of the four sides that constitute the end face  62  of the first rectangular pipe  60   a  may be welded to the side face  63  of the second rectangular pipe  60   b.    
     As shown in steps S 2  and S 3 , the protrusions  71  and  72  of the jig  7  are respectively inserted into the first holes  64  and the second holes  65  serving as the corresponding positioning holes when the first rectangular pipe  60   a  and the second rectangular pipe  60   b  are welded. 
     &lt;Step S 4 &gt; 
     Next, aftertreatment, such as deburring of the welds  61 , is performed in step S 4 . This completes the production of the structure  6 . 
     The structure  6  produced by the above-described production method does not cause variations in the dimensions of the end face  62  of the first rectangular pipe  60   a  to affect the positional relationship between the first rectangular pipe  60   a  and the second rectangular pipe  60   b . As a result, the structure  6  can achieve high dimensional accuracy.