Patent Publication Number: US-2013240568-A1

Title: Molten wax pumping device and molten wax dispenser using same

Description:
BACKGROUND OF THE INVENTION 
     (a) Field of the Invention The present invention relates to electrical wax injection technology and more particularly to a molten wax pumping device and a molten wax dispenser using the molten wax pumping device. 
     (b) Description of the Prior Art 
     Lost-wax casting is a method of metal casting in which a special wax is injected into a metal die, creating patterns that are compiled into a cluster around a wax runner system. After the pattern is coated with layers of refractory material, it is then heated to drain the wax. Once the wax is drained away, a hot mold is cast. After cooling, the mold is removed through the use of vibration, high pressure water blasting, impacting, grit blasting, or chemical dissolution. This process is practical for casting fine products. When making a wax mold, many devices are needed, including a wax melting machine, a molten wax dispenser and a wax injection machine. During a wax mold fabrication process, solid wax is melted by a wax melting machine, and then the molten wax is filled into a molten wax dispenser where the temperature of the molten wax is regulated, and then the molten wax is dispensed into a wax injection machine for injection into a mold die. 
     During the operation of the molten wax dispenser to dispense the molten wax into the wax injection machine, a molten wax pumping device should be used to pump the molten wax out of the molten wax dispenser into the wax injection machine. A conventional molten wax pumping device for this purpose generally comprises a pump body, a piston and a driving mechanism. The pump body comprises an inlet, an outlet, and two check valves respectively mounted in the inlet and the outlet. The inlet of the pump body is connected to the molten wax dispenser. The outlet of the pump body is connected to the wax injection machine. The piston is mounted in the pump body and alternately moved back and forth in the pump body to draw the molten wax into the inlet and to force the intake molten wax out of the outlet. The driving mechanism is adapted for reciprocating the piston. 
     According to the aforesaid pumping method, two check valves must be respectively mounted in the inlet and outlet of the pump body to restrict the flowing direction of the molten wax during the pumping operation. The use of the check valves in the pump body complicates the structure of the molten wax pumping device and increases the maintenance frequency. During the pumping action, the molten wax pumping device may be unable to draw in a sufficient amount of the molten wax, leading to low efficiency. 
     Therefore, there is a strong demand for a molten wax pumping device for the molten wax dispenser, which eliminates the aforesaid drawbacks. 
     SUMMARY OF THE INVENTION 
     The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide a molten wax pumping device and a molten wax dispenser using same, which has the advantages of simple structural design, ease of maintenance and high molten wax pumping efficiency. 
     It is another object of the present invention to provide a molten wax pumping device and a molten wax dispenser using same, which uses a linear reciprocating device to reciprocate a pump rod in an out of a pump body, thereby pumping a molten wax out of a molten wax tank into a pump hole in the pump body toward a material outlet. During the forward stroke of the pump rod, a piston at one end of the pump rod is out of the pump hole of the pump body, allowing the molten wax to flow out of the molten wax tank into the pump hole. During the back stroke of the pump rod, the piston is moved with the pump rod into the inside of the pump hole of the pump body, forcing the intake molten wax out of the pump hole into the material outlet toward a wax injection machine or other equipment. 
     It is still another object of the present invention to provide a molten wax pumping device and a molten wax dispenser using same, which enables the molten wax in the molten wax tank to be regulated to an optimal temperature for pumping by the molten wax pumping device to a wax injection machine or other equipment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of a molten wax pumping device in accordance with the present invention. 
         FIG. 2  is a sectional perspective view of the molten wax pumping device in accordance with the present invention. 
         FIG. 3  is a sectional view of the molten wax pumping device in accordance with the present invention. 
         FIG. 4  is a sectional perspective view of a molten wax dispenser in accordance with the present invention. 
         FIG. 5  is a sectional view of the molten wax dispenser in accordance with the present invention. 
         FIG. 6  is a schematic drawing of the present invention, illustrating the pumping operation of the molten wax pumping device during a forward stroke of the pump rod. 
         FIG. 7  is a schematic drawing of the present invention, illustrating the pumping operation of the molten wax pumping device during a backward stroke of the pump rod. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1-4 , a molten wax pumping device in accordance with the present invention is installed in a molten wax dispenser  10 . The molten wax pumping device comprises a pump body  1 , a pump rod  2 , and a linear driving device  3 . 
     The pump body  1  comprises a body shell  11 , a pump hole  12 , and a material outlet  13 . The body shell  11  comprises a first end  111  mountable to the molten wax dispenser  10  for communication with the inside space of the molten wax dispenser  10 , a peripheral wall  112 , and a second end  113  opposite to the first end  111 . The pump hole  12  is a through hole communicating the first end  111  and the second end  113  for receiving a molten wax from the molten wax dispenser  10 . The material outlet  13  is formed in the peripheral wall  112  of the body shell  11 , and kept in communication with the pump hole  12  for the output of the molten wax. Alternatively, the material outlet  13  can be disposed beyond the peripheral wall  112  and kept in communication with the second end  113  for the output of the molten wax. 
     The pump rod  2  is an elongated rod member, comprising opposing pumping end  21  and connecting end  22 , a piston  23  mounted on the pumping end  21  and fitting the pump hole  12 . The pump rod  2  is inserted through the pump hole  12  of the pump body  1 , and drivable to move the piston  23  out of the pump hole  12  and the first end  111  of the body shell  11  for letting the molten wax flow into the pump hole  12 , or into the first end  111  of the body shell  11  and the pump hole  12  in forcing the intake molten wax toward the material outlet  13 . 
     The linear driving device  3  is connected to the second end  22  of the pump rod  2 , and adapted for reciprocating the pump rod  2  relative to the pump body  1 . The linear driving device  3  can be a pneumatic cylinder, hydraulic cylinder, or any other similar mechanism capable of reciprocating the pump rod  2 . According to this embodiment, the linear driving device  3  is a hydraulic cylinder consisting of a cylinder body  31  and a reciprocating rod  32 . The reciprocating rod  32  is movably coupled to the cylinder body  31  and connected to the connecting end  22  of the pump rod  2 . 
     The pump body  1 , the pump rod  2  and the linear driving device  3  are assembled to form the molten wax pumping device. As illustrated in  FIG. 4 , the molten wax pumping device is installed in the e molten wax dispenser  10  for pumping the molten wax out of the molten wax dispenser  10  to a wax injection machine or any other equipment. 
     Further, the aforesaid pump body  1  is a single piece member. Alternatively, the pump body  1  can be formed of two members. As illustrated in  FIGS. 1-3 , the pump body  1  comprises a receiving barrel  114  and a connecting barrel  115 . The receiving barrel  114  can be a hollow cylindrical or rectangular shell forming the second end  113  and defining therein a first pump hole segment  121  of the pump hole  12 . The connecting barrel  115  is a hollow cylindrical member, having one end thereof connected to the receiving barrel  114  and an opposite end thereof forming the aforesaid first end  111 . Further, the connecting barrel  115  defines therein a second pump hole segment  122  of the pump hole  12 . The first pump hole segment  121  and the second pump hole segment  122  form the pump hole  12 . 
     Referring to  FIGS. 1-3  again, to avoid molten wax leakage, the pump body  1  is equipped with a tubular gasket  14 . The tubular gasket  14  fits the pump hole  12 . Further, the tubular gasket  14  is mounted in the pump hole  12  (i.e., the first pump hole segment  121 ) adjacent to the second end  113 . The pump rod  2  is movably inserted through the tubular gasket  14 , with the connecting end  22  suspended outside the second end  113  of the pump body  1  for the connection of the linear driving device  3 . Thus, the tubular gasket  14  effectively prevents molten wax leakage. 
     Referring to  FIGS. 1-3  again, a connector  24  is provided at the connecting end  22  of the pump rod  2  and connected to the reciprocating rod  32  of the linear driving device  3 , allowing the linear driving device  3  to reciprocate the pump rod  2 . The connector  24  comprises a cap ring  241  fastened to the connecting end  22  of the pump rod  2 , and a fastening member, for example, tie screw  242  mounted in the cap ring  241  and fastened to the reciprocating rod  32  of the linear driving device  3 . Further, the cylinder body  31  of the linear driving device  3  can be mounted at the second end  113  or other part of the pump body  1  for enabling the reciprocating rod  32  to reciprocate the pump rod  2 . 
     Referring to  FIG. 5  and  FIG. 4  again, the molten wax dispenser  10  comprises a molten wax tank  101 . The pump body  1  of the molten wax pumping device is affixed to the molten wax tank  101  at one side, keeping the first end  111  of the body shell  11  and the pumping end  21  of the pump rod  2  inside the molten wax tank  101  for pumping out the storage molten wax  20 . In this application example, two molten wax pumping devices are mounted in the molten wax tank  101  at two opposite sides, and controlled to pump the storage molten wax  20  alternatively, enhancing molten wax dispensing efficiency. 
     Referring to  FIGS. 6 and 7 , during the operation of the linear driving device  3 , the reciprocating rod  32  carries the piston rod  2  alternately back and forth, thereby pumping the storage molten wax  20  out of the molten wax tank  101  to a wax injection machine or other equipment. During the forward stroke of the pump rod  2 , as shown in  FIG. 6 , the piston  23  is moved with the pumping end  21  out of the pump hole  12  of the pump body  1 , allowing the storage molten wax  20  to flow into the pump hole  12 . On the contrary, as shown in  FIG. 7 , during the backward stroke of the pump rod  2 , the piston  23  is moved with the pumping end  21  into the inside of the pump hole  12  of the pump body  1 , forcing the intake molten wax  20  out of the pump hole  12  into the material outlet  13  toward a wax injection machine or other equipment. 
     Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.