JPS6330871B2 - - Google Patents

Description

Detailed Description of the Invention Technical Field The present invention relates to a method and apparatus for integrally molding a resin guide member of a print head in which guide holes for linearly guiding each of a plurality of print wires are formed. It is.

Prior Art In molding this type of guide member, the guide hole is formed by arranging a plurality of wire rods at predetermined positions within a cavity of a mold and filling the cavity with synthetic resin. However, in this case, the wire rod may be curved due to the injection pressure of the synthetic resin, and there is a possibility that the guide hole cannot be formed in a straight line. When the guide hole is curved in this way, it becomes impossible to guide the print wire in a defined direction, causing problems in the function of the print head.

OBJECTS OF THE INVENTION An object of the present invention is to solve such problems and provide a molding method and apparatus that can reliably mold a guide member having a linear guide hole.

Embodiment Hereinafter, an embodiment embodying the present invention will be described based on the drawings. First, the structure of the guide member molded by the molding method and apparatus of this embodiment and the print head to which the guide member is assembled will be explained based on FIGS. 1 to 3. Inside the printing head 1 shown in FIG.
24 armatures 4 swingably supported by
are arranged radially, and straight printing wires 5 extending forward are fixed to their tips. A guide member 7 made of resin is fixed to the front surface of the front cover 6 of the print head 1 with pins 8. This guide member 7 includes a nose portion 7a and a flange portion 7 integrally formed on the outer periphery of the base end portion of the nose portion 7a.
b. As shown in FIG. 3, twenty-four linear guide holes 9 are provided through the nose portion 7a, through which the printing wire 5 is guided. The distal opening ends of the guide holes 9 are arranged in two rows, and the proximal opening ends are arranged in a ring. Further, a pin hole 10 for the pin 8 is transparently provided in the flange portion 7b.

The armature 4 is always attracted to the core 12 by the magnetic force of the permanent magnet 11, and the printing wire 5 is in the backward retracted position, and when the coil 13 is energized, the magnetic force of the permanent magnet 11 is canceled out. The armature 4 is rotated forward by the spring force of the leaf spring 2, and the printing wire 5 projects forward to perform printing. Note that the forward rotation of the armature 4 causes the printing wire 5 to move forward, and at the same time, a force is applied in a direction that causes it to swing slightly around the tip opening of the guide hole 9, so that swinging is allowed. In order to do this, the guide hole 9 is tapered so as to become slightly wider towards the rear side.

Next, the configuration of a molding apparatus for forming the guide member 7 will be explained based on FIGS. 4 to 7. This molding apparatus is a flow injection molding machine of the so-called flow molding type, which injects the resin in multiple steps while increasing the injection pressure. The rear surface of the mounting plate 21 (the fourth
A spool bushing 23 is fixed to the fixed mold plate 22 on the right side of FIG.
4 are configured. The mounting plate 21 and the spool bush 23 are provided with through holes 25a so as to communicate with each other.
and a recess 25b are formed, and the penetration recess 25 into which the injection nozzle 26 enters is formed by the through hole 25a and the recess 25b. Said recess 2
A gate hole 27 is provided between the inner top of the spool bush 5b and the rear side of the spool bush 23. In addition,
In this specification, the right side in FIGS. 4 to 7 is referred to as the rear part.

A movable receiving plate 28 is provided behind the fixed mold 24 so as to be movable back and forth, and a supporting member 30 having a receiving hole 29 is fixed to the front surface thereof. A molded member 31 is accommodated and fixed in the accommodation hole 29, and the guide member 7 is provided on the inner surface of the space provided at the center.
A molded surface 32 is formed to define the outer peripheral surface excluding the distal end surface and proximal end surface.

An accommodation recess 33 is formed on the rear surface of the molded member 31, and a moving member 34 is accommodated therein so as to be able to move back and forth slightly. The forward and backward movement of the moving member 34 is guided by the engagement of the guide pin 35 and the guide hole 36. This moving member 34 is fixed at the forward moving position shown in FIG. 5 by bolts (not shown) during mold setup. A storage recess 37 is formed on the front surface of the movable member 34, and a pull-out hole 3 is formed in the center of the movable member 34 so as to communicate with the storage recess 37.
8 is provided through the hole, and the rear end thereof is opened in a circular arc shape. Twenty-four fixing screws 39 are installed on the rear surface of the moving member 34 so as to surround the pull-out hole 38.
are screwed in and arranged in a ring. Note that the movable receiving plate 28 is formed with a recess 40 for accommodating the head 39a of the fixing screw 39.

Inside the storage recess 37 are two rear templates 41,
42 are housed in an overlapping state and are fixed to the moving member 34 with pins 43 and bolts 44. 7th
As shown in the figure, a protrusion 45 that is slidably fitted into the rear end of the molding surface 32 is provided at the center of the rear template 41 located at the front of both the rear templates 41 and 42. It is integrally formed, and the front surface of the protrusion 45 serves as a molding surface 45a for defining the front end surface of the guide member 7. As shown in Figure 7,
24 through holes 46a are formed in the center of both rear templates 41, 42 so as to communicate with each other,
A rear positioning hole 46 is formed by the through holes 46a that communicate with each other. This rear positioning hole 46 has the same arrangement as the tip opening of the guide hole 9 shown in FIG. The movable member 34 and both rear mold plates 41 and 42 constitute a rear mold member 47 that can be moved slightly back and forth within the accommodation recess 33.

A stepped accommodation hole 4 is provided on the front surface of the molded member 31.
A support member 49 with 8 is arranged. The support member 49 includes a plurality of sets (only one set is shown) of guide pins 5
0 and the guide hole 51, the molded member 31
The relative position is determined. The accommodation hole 48
A front template 52 is fitted inside and fixed with bolts 53, and a molding surface 54 for defining the rear surface of the nose portion 7a and flange portion 7b of the guide member 7 is formed on the front surface thereof. . The molding surface 54, the molding surface 32 of the molding member 31, and the molding surface 45a of the rear template 41 constitute a cavity 55 for molding the guide member 7.

Four plate-shaped spacers 56 are arranged in an overlapping manner on the front surface of the front template 52 to secure bolts 57 and pins 5.
8. Spacer 5 at rear end position
A molded pin 59 is fixed to 6, and its tip protrudes into the cavity 55 to define the pin hole 10 of the guide member 7. 6th
As shown in the figure, a through hole 60a is formed in the center of each spacer 56 and the front template 52, and the cavity 55 and the gate hole 27 are provided with a through hole 60a.
A gate hole 60 communicating with is formed. Each of the spacers 56 and the front template 52 has 24 through holes 6 so as to surround the gate holes 60.
1a are formed so as to communicate with each other, and 24 front positioning holes 61 are formed. Each front positioning hole 61 has an oblique shape having the same inclination as each guide hole 9 by slightly shifting each through hole 61a.

The molding member 31, the support member 49, the front mold plate 52, and each spacer 56 constitute a front mold member 62, and the front mold member 62, the rear mold member 47, the support member 30, and the movable receiver The plate 28 constitutes a movable mold 63 that can move toward and away from the fixed mold 24 based on back and forth movement. The parting line between the two dies 24 and 63 is between the dashed dotted lines indicated by P.

The front positioning hole 61 and the rear positioning hole 4
Twenty-four wire rods 64 for defining the guide holes 9 are inserted through the wire rods 6 and pass through predetermined positions within the cavity 55. Each wire 64 has a head 64a integrally formed at one end thereof, which is hooked to the spacer 56 at the front end, and the other end passes through the pull-out hole 38 of the moving member 34 and is wound and fixed around the fixing screw 39, held in tension. Further, the wire 64 is made thicker toward the head 64a so that the tapered guide hole 9 described above can be formed.

In addition, on the rear surface of the spool bush 23, there are heads 53a, 57a of the bolts 53, 57, a head 50a of the guide pin 50, and a head 64a of the wire 64.
Recesses 65, 66, 67, to avoid interference with
68 is formed.

Next, a molding method using the molding apparatus configured as described above will be explained. First, as shown by two-dot chain lines in FIG. 4, in a state where the movable mold 63 is divided at the parting line P and moved backward, the movable member 34 is moved until it touches the inner bottom surface of the accommodation recess 33 of the molded member 31. move it forward,
It is secured in its forward position by bolts (not shown). At the same time, the support member 49 is moved rearward, and the front template 52 is brought into close contact with the front surface of the molded member 31. Therefore, at this stage, each molding surface 54, 3 of the front template 52, molding member 31, and rear template 41 is
2 and 45a form a cavity 55.

Next, pass the 24 wire rods 64 through the front positioning hole 61 and the rear positioning hole 46, and attach the tips to the fixing screws 3.
9 and each wire rod 64 is placed under tension at a predetermined position within the cavity 55. Thereafter, the fixation of the movable member 34 by the bolt is released so that the entire rear mold member 47 including the movable member 34 can move rearward.

After doing this, as shown by the solid line in FIG. 4, the movable mold 63 is moved forward and brought into close contact with the rear surface of the fixed mold 24, and then the injection nozzle 26 is advanced into the entry recess 25. Then, primary injection of the molten synthetic resin into the cavity 55 was performed for 7 seconds at an injection pressure of 850 kg/cm ² , followed by secondary injection for 20 seconds at an injection pressure of 1150 kg/cm ² , and then Then, tertiary injection is performed at an injection pressure of 1350 Kg/cm ² for 20 seconds, and then cooling is performed for 80 seconds while maintaining that pressure to solidify the molten synthetic resin. By performing the injection into the cavity 55 in multiple steps while increasing the filling pressure in this way, shrinkage due to solidification of the synthetic resin does not occur, and the cavity 55 can be formed accurately to the same size.

Particularly in this case, the resin pressure within the cavity 55 acts on the rear mold member 47 as a force to move it rearward, so the wire rod 64 receives tensile force in the direction along its center line and becomes even more tensioned, and the resin As the pressure increases, the tension increases. That is, since the resin pressure is used to tension the wire 64, bending of the wire 64 due to the resin pressure can be prevented, the wire 64 always maintains a straight state, and a straight guide hole 9 can be formed.

By the way, if there is no means to tension the wire according to the resin pressure, the resin pressure will cause the wire inside the cavity to bulge and curve, making it impossible to form a straight guide hole. Become.

Once the synthetic resin in the cavity 55 has solidified in this way, the movable mold 63 is moved back and the fixed mold 24 is
After the wire rods 64 are separated from each other, the fixing screws 39 are loosened to release the winding fixation of the wire rods 64, and each wire rod 64 is pulled out from the guide member 7. Thereafter, the support member 49 is separated from the molded member 31, the front end side of the cavity 55 is opened, the guide member 7 is taken out from the cavity 55, and the resin at the gate holes 27 and 60 is cut off.

In the above embodiment, the resin pressure in the cavity 55 is applied to the rear mold member 47, and tension is applied to the wire 64 through the rear mold member 47. It may be configured to apply tension to the wire rod 64 via the mold member 62. Further, in the above embodiments, the present invention is embodied in a fluid injection molding machine, but the present invention may be embodied in a general injection molding machine.

Effects of the Invention As exemplified in the embodiments above, this invention applies tensile force to each wire along its center line by the injection pressure of the resin injected into the cavity. It is always maintained in a tensioned state and exhibits an excellent effect of reliably forming a guide member having an accurate linear guide hole. or,
This invention is simply configured so that the wire rod receives tensile force when the two mold members move relative to each other due to the injection pressure of the resin, so there is no need for a complicated configuration, and it is an extremely simple structure that is similar to the one described above. It also exhibits the effect of being able to mold a guide member like the one described above.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side view of a print head with a guide member, FIG. 2 is an enlarged perspective view of the guide member,
FIG. 3 is an enlarged front view of the guide hole, and FIGS. 4 to 7 show a molding device embodying the present invention. FIG. 4 is a sectional view of the molding device during resin filling, and FIG. Figure 5 is a cross-sectional view of the molding device before filling with resin, Figure 6 is an enlarged cross-sectional view of the front positioning part of the wire rod, and Figure 7 is an enlarged cross-sectional view of the rear positioning part of the wire rod. . Printing wire...5, Guide member...7, Guide hole...9, Injection nozzle...26, Rear mold member...4
7, Cavity...55, Front mold member...62,
Wire rod...64.

Claims (1)

[Scope of Claims] 1. A molding method for integrally molding a resin guide member 7 of a print head in which guide holes 9 for linearly guiding each of a plurality of print wires 5 are formed, the outer shape of the guide member 7 being defined. a step of assembling molds 47, 62, etc. having at least two relatively movable mold members in order to form a cavity 55; A step of fixing the wire rod 64 to both mold members at both ends and arranging it at a predetermined position, injecting resin into the cavity 55, and relative movement of the mold members due to the injection pressure A guide comprising the steps of applying a tensile force to the wire rods 64 along their respective center lines, and after the resin in the cavity 55 is solidified, removing the wire rods 64 and taking out the guide member 7 from the molds 47, 62, etc. Method of forming parts. 2. In a molding device for integrally molding a resin guide member 7 of a print head in which guide holes 9 for linearly guiding each of a plurality of print wires 5 are formed, a cavity 55 defining the outer shape of the guide member 7 is formed. at least two relatively movable mold members 47, 62 for forming the guide hole 9; a plurality of wire rods 64 disposed; a means 26 for injecting resin from one mold member 47 or 62 into the cavity 55 along the longitudinal direction of the wire rods 64 toward the other mold member 62 or 47; The resin is supplied to the cavity 55 from the injection means 26 etc.
The guide member is characterized in that when the wire rod 64 is injected into the mold member, the wire rod 64 receives a tensile force in the direction of their respective center lines due to the relative movement of the mold members 47 and 62 due to the injection pressure of the resin. Molding equipment.