Abstract:
An injection mold includes a first mold part ( 10 ), a second mold part ( 50 ) mating with the first mold part, a sliding block ( 20 ), a cam actuator ( 30 ), and a rack ( 40 ). The sliding block is movably disposed on the first mold part. The cam actuators resist the sliding block for driving the sliding block to move along the first mold part. The rack is fixed to the second mold part for actuating the cam actuator.

Description:
FIELD OF THE INVENTION  
       [0001]    The present invention generally relates to injection molds and, more particularly, to an injection mold with a sliding block. 
       DESCRIPTION OF RELATED ART  
       [0002]    Injection molding is a conventionally known and commonly used manufacturing process. A typical injection mold has a sliding block for injection molding complicated parts that have lateral holes or recesses. The sliding block can be moved relative to a die disposed in the mold by an actuator member, thus a molded part with a desired shape can be formed. The actuator member for moving the sliding block is very important to the accuracy of the shape of the molded part. 
         [0003]    Referring to  FIG. 6 , a conventional injection mold includes an upper mold die  81 , a lower mold die  82  with a core  821 , and two sliding blocks  83  movably disposed on two sides of the core  821  respectively. The upper mold die  81  has one pair of symmetrical slanting slots  811  defined for mounting a pair of guiding rods  812  therein. Each of the sliding blocks  83  has a slanting guiding hole  831 . Each of the guiding rods  812  engages in a corresponding slanting guiding hole  831 . When the upper mold die  81  moves toward the lower mold die  82 , the guiding rods  812  actuate the sliding blocks  821  to move towards the core  821  until the upper mold die  81  engages with the lower mold die  82 . However, the manufacturing process of the injection mold is complicated. Furthermore, abrasion of the guiding rods  812  and the slanting guiding hole  831  may cause the guiding rods  812  to become misaligned with or a poor fit to the slanting guiding hole  831 , thus it may be difficult to reach a desired accuracy for molded parts. 
         [0004]    What is needed, therefore, is a simple injection mold, which can reach high accuracy for molded parts. 
       SUMMARY OF THE INVENTION 
       [0005]    In one embodiment thereof, an injection mold is provided. The injection mold includes a first mold part, a second mold part mating with the first mold part, a sliding block, a cam actuator, and a rack. The sliding block is movably disposed on the first mold part. The cam actuator resists the sliding block for driving the sliding block to move along the first mold part. The rack is fixed to the second mold part for actuating the cam actuator. 
         [0006]    Other advantages and novel features will become more apparent from the following detailed description of preferred embodiment when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Many aspects of the injection mold can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the injection mold. Moreover, in the drawings, like reference numerals designate corresponding ms throughout the several views. 
           [0008]      FIG. 1  is an exploded, perspective view of an embodiment of the injection mold; 
           [0009]      FIG. 2  is a schematic view of the sliding block of the injection mold in  FIG. 1 ; 
           [0010]      FIG. 3  is a schematic view of the female mold part of the injection mold in  FIG. 1 ; 
           [0011]      FIG. 4  is a cut-away view of the injection mold, showing an open state; 
           [0012]      FIG. 5  is a cut-away view of the injection mold, showing a closed state; and 
           [0013]      FIG. 6  is a schematic view of a conventional injection mold with sliding blocks. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    Referring to  FIG. 1 , an injection mold in accordance with a preferred embodiment includes a male mold part  1   0 , a sliding block  20 , two cam actuators  30 , two racks  40 , a female mold part  50 , and two springs  60 . 
         [0015]    The male mold part  10  is provided with a top wall  11 . The top wall  11  has a mold core  12  mounted thereon, a sliding guide member  13  disposed at one side of the mold core  12 , and a pair of through holes  14  defined either side of the sliding guide member  13 . The sliding member  12  serves to slidably fit the sliding block  20 , and the sliding guide member  13  is provided with a guiding wall  131  and one pair of opposing first sidewalls  132 . The guiding wall  131  has a pair of parallel linear rails  133  formed thereon. Each of the rails  133  has a T-shaped cross section. Each of the first sidewalls  132  has a first holding pin  134  and a positioning hole  135  disposed thereon. The first holding pin  134  serves to hold one of the springs  60 , and the positioning hole  135  serves to fix a corresponding one of the cam actuators  30  on one of the sidewalls  132 . 
         [0016]    Referring to  FIG. 1  and  FIG. 2 , the sliding block  20  is provided with a sliding wall  21 , one pair of opposing second sidewalls  22 , and a molding pin  23  for forming a part  70  of desired shape. The sliding wall  21  has a pair of T-shaped linear sliding grooves  211  formed thereon and a pair of second holding pins  213  disposed thereon. The sliding grooves  211  are configured for accommodating the rails  133 . The second holding pins  213  are contiguous with the second sidewalls  22  and serve to hold the springs  60 . Each of the second sidewalls  22  has an arcuate groove  221  formed thereon. The arcuate groove  221  is provided with an arcuate grooved wall  223 . The molding pin  23  is disposed on one end of the sliding block  20  and serves for molding a hole on the part  70  being molded by the injection mold. 
         [0017]    Each of the cam actuators  30  includes a gear portion  31 , a cam portion  32 , and a positioning shaft  33 . The gear portion  31  has a cog surface consisting of an essentially smooth first surface and a second surface advantageously occupying about 20% to 80%, of the cog surface. The second surface has a plurality of teeth radially formed thereon, thereby permitting the engagement of the gear portion  31  with a corresponding one of the racks  40 . The cam portion  32  is integrally formed on the first surface of the gear portion  31 . The gear portion  31  is rotatably coiled around the positioning shaft  33 , with one end of the positioning shaft  33  extending out of the gear portion  31 . The end of the positioning shaft  33  extending out of the gear portion  31  can be secured in the positioning hole  135 . Thus the gear portion  31  and the cam portion  32  can be fixed on the first sidewalls  132  and rotate around the positioning shaft  33 . 
         [0018]    Each of the racks  40  includes a securing portion  41  and engaging portion  42 . The engaging portion  42  has a strip-like shape, and has an engaging side  421  with a plurality of teeth formed thereon. One end of the engaging portion  42  can be received in a corresponding one of the through holes  14  of the male mold part  10 . 
         [0019]    Referring to  FIG. 1  and  FIG. 3 , the female mold part  50 , which mates with the male mold part  10 , is provided with a working wall  51  and a recessed portion  52  corresponding to the top wall  11  and the mold core  12  respectively. The working wall  51  has a receiving groove  53  corresponding to the sliding guide member  13 , and two positioning grooves  55 . The receiving groove  53  is formed at one side of the recessed portion  52  for receiving the sliding guide member  13  when the injection mold is closed. The positioning grooves  55  are disposed at two sides of the receiving groove  53  respectively, and each of positioning grooves  55  serves to secure the securing portion  41  of a corresponding one of the racks  40 . 
         [0020]    Referring to  FIG. 4  and  FIG. 5 , in assembly of the injection mold, the sliding block  20  is engaged with the sliding guide member  13 , with the molding pin  23  facing towards the mold core  12 . The rails  133  are each slidably received in a corresponding sliding groove  211 . The second holding pins  213  of the sliding block  20  are hung at two sides of the sliding guide member  13 . The first holding pin  134  holds one end of a corresponding one of the springs  60 , and one of the second holding pins  213  holds the other end of the corresponding one of the springs  60 . The end of the positioning shaft  33  extending out of the gear portion  31  is secured in the positioning hole  135 , with the cam portion  32  resisting the arcuate grooved wall  223  of the arcuate groove  221 . The securing portion  41  of one of the racks  40  is secured in a corresponding one of the positioning grooves  55  of the female mold part  50 , with the engaging portion  42  engaging with the gear portion  31  of one of the cam actuators  30  and aligning with a corresponding one of the through holes  14  of the male mold part  10 . The male mold part  10 , the sliding block  20 , the cam actuators  30 , the racks  40 , the female mold part  50 , and the springs  60  are assembled together thereat. 
         [0021]    When the injection mold is being closed, the female mold part  50  moves toward the male mold part  10  along a first axis that is parallel to the engaging side  421  of the racks  40 . Simultaneously, the springs  60  apply a pulling force to draw the sliding block  20  toward the mold core  12  along a second axis. The second axis is positioned parallel to the rails  133  and perpendicular to the first axis. A mold cavity can thereby be defined by the mold part  10 , the female mold part  50 , and the sliding block  20 , with the molding pin  23  of the sliding block  20  extending into the molding cavity. Molten materials can be filled into the mold cavity to form the part  70 . 
         [0022]    When the injection mold is being opened, the female mold part  60  moves away from the male mold part  1   0  along the first axis, simultaneously the rack  40  actuates the gear portion  31  and the cam portion  32  of the cam actuators  30  to rotate around the positioning shaft  33 . The cam portion  32  may push the sliding block  20  apart from the mold core  12  along the second axis with the springs  60  being extended, thereby the molded part  70  can be taken away from the injection mold. 
         [0023]    It should be understood that the springs  60  could be omitted in the injection mold. When the injection mold is being closed, the racks  40  can drive the cam actuators  30  to rotate around the positioning shaft  33 , and the cam actuators  30  can push the sliding block  20  to move towards the mold core  12 . 
         [0024]    It should be understood, however, that even though numerous characteristics and advantages of the present embodiment have been set forth in the foregoing description, together with details of the structures and functions of the embodiment, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.