Patent Publication Number: US-2011072877-A1

Title: Marking apparatus using magnetism

Description:
BACKGROUND OF THE INVENTION  
     1. Field of the Invention 
     The present invention relates to an apparatus for marking a metal, and more particularly, to a metal marking apparatus in which a plunger for marking a surface of a metal vertically reciprocates using magnetism to improve a stamping force and a life of the apparatus even through the plunger is reduced in thickness. 
     2. Description of the Related Art 
     In general, proper serial numbers that indicate a manufacturing date, a manufacturer, etc., are marked to effectively manage corresponding parts in chassis and parts of a vehicle, main parts of an airplane, and the like. 
     Such a marking apparatus, as shown in  FIGS. 7 and 8 , is disclosed in Korean Publication Patent No. 2001-0067566 filed by the same applicant. According to the marking apparatus, two solenoid valves  140  and  150  are alternately opened and closed to supply pressure air to an air tube  202  of a stamping part  170  through a pressure air intake part  130 , thereby allowing the pressure air to fill a pressure chamber  212  and also allowing a piston  222  to get forward. 
     The advancing piston  222  marks an object  300  using a stamping pin  242  and returns by an elastic force of a return spring  230 . The compressed air advancing the piston  222  is exhausted through exhaust parts  145  and  155  by the returning piston  222 . 
     However, in such the air pressure marking apparatus, a great exhaust noise (above 80 db) may be generated by the air pressure. Also, since a compressor that is a separate air generation device is required, a structure of the marking apparatus is complicated and a manufacturing cost is expensive. In addition, the marking apparatus breaks down easily. 
     Thus, to overcome the above-described limitations of the related art air pressure marking apparatus, a marking apparatus using magnetism is being developed. A structure of the marking apparatus using the magnetism will be described. 
       FIG. 9  is a sectional view of a related art magnetic marking apparatus, and  FIG. 10  is a view of a state in which a plunger of a related art magnetic marking apparatus marks a metal while descending. 
     An operation body  310  is coupled to a lower portion of an upper cover  300 . A lower body is coupled to a lower portion of the operation body  310 , and a plunger  330  is coupled to the inside of the operation body  310 . Thus, the plunger  330  is elastically supported by an elastic unit  340 . 
     A vertically penetrated cylindrical part  311  is disposed at a center of the operation body  310 . An electromagnetic coil  312  is disposed outside the cylindrical part  311 , and a control part  313  for controlling the electromagnetic coil  312  is separately disposed and connected to the electromagnetic coil  312 . 
     An induction part  321  vertically passes through the lower body  320 . A sleeve  322  for straightly inducing a stamping pin is disposed outside the induction part  321 . An electric unit insertion groove  323  having a width greater than that of the induction part  321  is defined in an upper portion of the induction part  321 . 
     The plunger  330  includes a head part  331 , a stamping rod  332 , and a stamping pin  333 . The head part  331  is formed of a pure iron (Fe) to achieve maximum efficiency by the magnetism. The stamping rod  332  is formed of cemented carbide material to endure an impact colliding with the lower body  320 . Also, the stamping pin  333  has a thin and long shape to easily mark the metal M. The plunger  330  is coupled to and supported by the elastic unit  340  inserted into the elastic unit insertion groove  323 . 
     Thus, in the marking apparatus including the above-described components, when the current is applied to the electromagnetic coil  312  by the control part  313 , an electromotive force is generated to descend the plunger  330 . As a result, the metal M is marked by the stamping pin  333  of the descending plunger  330 . 
     Since the stamping rod  332  of the descending plunger  330  compresses the elastic unit  340  and a bottom surface of the stamping rod  332  has an angle of about 180° equal to a horizontal line, the stamping rod  332  strongly collides with the lower body  320  and thus does not descend any longer. 
     Then, when the electromotive force is removed, the plunger  333  ascends by the elastic unit  340  to return its original position. 
     However, in the related art marking apparatus, when the stamping rod  332  collides with the lower body  320  while descending, the stamping rod  332  and a top surface of the lower body  320  are horizontal)(180° to each other. As a result, a frictional force increases and a stroke is shorter, and thus, an efficient stamping force is not generated. 
     Thus, the plunger  330  has a wide width to increase a load, thereby improving the electromotive force. As a result, the overall outer size of the marking apparatus increases to increase manufacturing costs. In addition, the stamping speed is reduced to reduce the marking speed. 
     Also, since the stroke is reduced, it may be difficult to mark an uneven surface or a curved surface. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a marking apparatus that improves a related art inefficient stroke to improve a stamping speed and a marking speed, thereby improving a stamping force. 
     Another object of the present invention is to provide a marking apparatus that reduces the overall outer size to reduce manufacturing costs and improves a stamping force than that of a related art marking apparatus to improve its life. 
     According to an aspect of the present invention, there is provided an apparatus for marking a metal using magnetism, the apparatus including: an upper body having an elastic unit insertion groove in which an elastic unit is inserted; an operation body through which a cylindrical part having a diameter less than that of the elastic unit insertion groove vertically passes, the operation body being coupled to a lower portion of the upper body, wherein an electromagnetic coil is disposed around the cylindrical part; a lower body through which an induction part having a diameter less than that of the cylindrical part vertically passes, the lower body being coupled to a lower portion of the operation body; a control part connected to the electromagnetic coil of the operation body to control an electromotive force of the electromagnetic coil; a plunger including an upper head part inserted into the elastic unit insertion groove of the upper body, a middle stamping rod inserted into the cylindrical part of the operation body, and a lower stamping pin inserted into the induction part of the lower body; and an elastic unit coupled to the stamping rod of the plunger and inserted into the elastic unit insertion groove of the upper body to elastically support the plunger. 
     A tapered part having a gradually decreasing diameter may be disposed on a lower end of the cylindrical part of the operation body, and a tapered part having a shape corresponding to that of the lower end of the cylindrical part including the tapered part may be disposed on a lower end of the stamping rod of the plunger. 
     An angle between the cylindrical part of the operation body and the tapered part of the stamping rod of the plunger may be about 30°. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
         FIG. 1  is an exploded perspective view illustrating a partial section of a marking apparatus according to an embodiment of the present invention; 
         FIG. 2  is an enlarged sectional view illustrating an operation body of a marking apparatus according to an embodiment of the present invention; 
         FIG. 3  is a graph illustrating a variation of suction force according to angle and configuration of plunger (movable core); 
         FIG. 4  is an enlarged view illustrating a plunger of a marking apparatus according to an embodiment of the present invention; 
         FIG. 5  is an assembled sectional view of a marking apparatus according to an embodiment of the present invention;. 
         FIG. 6  is a view of a state in which a plunger marks a metal using magnetism while the plunger descends by an electromotive force of control part in  FIG. 5 ; 
         FIG. 7  is a block diagram of a related art pneumatic marking apparatus; 
         FIG. 8  is a sectional view of a related art pneumatic marking apparatus; 
         FIG. 9  is a sectional view of a related art magnetic marking apparatus; and 
         FIG. 10  is a view of a state in which a plunger of a related art magnetic marking apparatus marks a metal while descending. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
       FIG. 1  is an exploded perspective view illustrating a partial section of a marking apparatus according to an embodiment of the present invention. 
     A marking apparatus D according to the present invention includes an upper body  10 , an operation body  20 , a lower body  40 , a plunger  50 , and an elastic unit  60 . 
     A downwardly opened elastic unit insertion groove  11  is defined with a predetermined depth in the upper body  10 . A sleeve  11   a  for straightly inducing a stamping rod  52  may be further disposed at an inlet side of the elastic unit insertion groove  11 . 
       FIG. 2  is an enlarged sectional view illustrating an operation body of a marking apparatus according to an embodiment of the present invention. 
     A vertically penetrated cylindrical part  21  is disposed at a center of the operation body  20 . The cylindrical part  21  has a diameter less than that of the elastic unit insertion groove  11  defined in the upper body  10 . This is done for reasons that a head part  51  (that will be described below) of the plunger  50  and the elastic unit  60  are hooked on the cylindrical part  21 , but are inserted into the cylindrical part  21 . 
     A tapered part  22  having a gradually decreasing diameter is disposed at a lower end of the cylindrical part  21 . An angle between both tapered surfaces of the tapered part  22  may be about 30°. An electromagnetic coil  23  is disposed outside the cylindrical part  21 . A control part  30  is connected to the electromagnetic coil  23 . 
       FIG. 3  is a graph illustrating a variation of a suction force (marking force) according to an angle and configuration of a plunger (movable core) of a solenoid valve. 
     This graph is disclosed on a web-page with the http://www.solenoid.co.kr/tech/tech4.htm. 
     According to the graph shown in  FIG. 3 , when the plunger has an angle of about 30°, it is seen that a stroke increases even through any large force is not applied. 
     Thus, when a strong stamping force is applied to mark a metal M, an angle between both tapered surfaces of the tapered part  22  was about 30° in consideration of deformation and wear of the plunger. 
     The lower body  40  includes an induction part  41  having a diameter less than that of the cylindrical part  21  of the operation body  20  and vertically passing therethrough. A sleeve for straightly inducing a stamping pin  53  may be disposed outside the induction part  41 . 
       FIG. 4  is an enlarged view illustrating a plunger of a marking apparatus according to an embodiment of the present invention. 
     The plunger  50  has a predetermined length and includes the head part  51 , the stamping rod  52 , and the stamping pin  53 . 
     The head part  51  has a diameter insertable into the elastic unit insertion groove  11  of the upper body  10 . Since the stamping rod  52  has a diameter closely insertable into the cylindrical part  21  of the operation body  20 , the stamping rod  52  has a diameter less than that of the head part  51 . The stamping pin  53  is disposed at a lower portion of the stamping rod  52  and has a thin and long shape. Also, the stamping pin  53  has a diameter insertable into the induction part  41 . 
     In particular, a tapered part  54  corresponding to the tapered part  22  disposed on the cylindrical part  21  of the operation body  20  is disposed at a lower end of the middle stamping rod  52  of the plunger  50 . An angle between both tapered surfaces of the tapered part  54  may be about 30°. 
     That is, since the plunger  50  includes the tapered part  54  having a cone shape than a simple flat shape having a planar bottom surface, the plunger  50  may be slim in configuration. 
     In spite of the slim plunger  50 , as shown in the graph, the plunger  50  has a suction force (stamping force) approximately three times or more greater than that of a related art plat type plunger. Also, since the overall plunger is formed of cemented carbide, a life of the plunger  50  may be improved by more than ten times. 
     The elastic unit  60  is wound around and coupled to the middle portion of the stamping rod  52  of the plunger  50 . The elastic unit  60  is inserted into the elastic unit insertion groove  11  of the upper body  11  and then coupled in a hung state between a lower end of the head part  51  and an upper end of the operation body  20 . 
       FIG. 5  is an assembled sectional view of a marking apparatus according to an embodiment of the present invention. 
     The operation body  20  is fixedly coupled to an upper side of the lower body  40 . A side of the stamping pin  53  of the plunger  50  is inserted into and coupled to the cylindrical part  21  of the operation body  20 . Here, the elastic unit  60  is fitted into and coupled to the stamping rod  52  of the plunger  50 . The stamping rod  52  is induced by the sleeve  11   a  disposed at the inlet side of the elastic unit insertion groove  11  to straightly induce the stamping rod  52  while moving through the cylindrical part  21 . As a result, the stamping rod  52  has straightness. 
     When the tapered part  54  of the plunger  50  does not descend any longer by the tapered part  22  disposed on the cylindrical part  21  of the operation body  20 , the upper body  10  is fixedly coupled to an upper portion of the operation body  20 . Here, the head part  51  of the plunger  50  and the elastic unit  60  are inserted into and coupled to the elastic unit insertion groove  11  of the upper body  10 . 
     Although not shown, the marking apparatus D may be fixedly coupled to mark desired characters while moving along an X-axis and Y-axis by a transfer motor. 
     Hereinafter, an operation of the marking apparatus including the above-described components will be described. 
       FIG. 6  is a view of a state in which a plunger marks a metal using magnetism while the plunger descends by an electromotive force of control part in  FIG. 5 . 
     When the control part  30  applies 24 volts DC current having a variable frequency from about 1 Hz to about 40 Hz, the plunger  50  momentarily strongly descends about one time to about forty times per second by an electromotive force of the electromagnetic coil  23  to allow the stamping pin  53  to mark the metal M. 
     Here, the stamping pin  53  is inducted by the sleeve  42  disposed outside the induction part  41  to induce straightly induce the stamping pin  53  while the plunger  50  descends to allow the stamping pin  53  having a thin and long length to move through the induction part  41  of the lower body  40 . As a result, the stamping pin  53  has straightness. 
     Also, when the plunger  50  descends by the momentary electromotive force, since the stamping rod  52  has the cone shape, the electromotive force between the tapered part  54  of the stamping rod  52  and the tapered part  22  of the operation body  20  increases to improve a stamping force when compared to the related art marking apparatus. 
     The head part  51  of the plunger  50  descending by a signal transmitted from the control part  30  descends to compress the elastic unit  60 . The plunger  50  completely performing the marking process ascends by an elastic force of the elastic unit  60  to return to its original position. 
     According to the present invention, the plunger  50  descends by one control part  30  and ascends by the elastic unit  60 . Thus, a quick operation may be performed, and also the stamping force may be optimized to perform a high speed marking process. 
     Therefore, the plunger has the diameter less than that of the related art plunger to minimize a frictional force and improve the stamping force by approximately three times or more. Also, the stroke increases to improve the stamping force. In addition, it may be possible to mark the uneven surface or the curved surface, and the marking speed is improved to realize a very efficient marking apparatus. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.