Abstract:
A support system is made up of a plurality of alternating rods and sleeves. Each sleeve forms a pair of sockets configured to movably receive and retain one of the first or second ends of adjacent rods, forming a bendable linkage. A cover is provided to surround the linkage, and a coupler is provided to cover the linkage. An electrical switch may be provided within one of the joints between sleeves and rods whereby movement of the rod relative to the sleeve actuates the switch.

Description:
FIELD OF THE INVENTION 
     This invention relates to a jointed support system and methods to construct the same. More particularly, this invention relates to molding processes and methods of constructing many different types of support systems and structures at a relatively low cost and from a number of discrete components. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     For convenience of description, the invention will hereinafter be described, by way of example, in terms of a skeleton for a doll, a figure or toy. However, it should be understood that the invention applies equally well to many different types of devices. Some of these devices may be used for leisure or recreational devices such as toys, play jewelry, or the like. Another use of the invention might be industrial, as, for example, making a hollow spout for a gas can. Other of these devices may be utilitarian, such as a chain, stand, or the like. 
     An object of the invention is to provide a method of constructing structures from molded plastic parts which are produced at a reasonable cost from the fewest number of different part designs. For example, a chain might be made from only two types of discrete parts which can be snapped together. These same two types of parts may be used to make the skeleton of a toy. 
     Another object of the invention is to provide a method which enables a reduced cost for assembly by minimizing the required hand assembly. Here, an assembly machine should have general utility to assemble different types of parts into any of many different configurations. 
     Yet another object of the invention is to provide devices having a wide ranging freedom of movement in order to make jointed, movable structures. For example, a doll or toy should be able to move its body and limbs with a degree of freedom which is approximately the same degree of freedom enjoyed by the animal represented by the doll or toy. 
     A further object of the invention is to provide a jointed structure which may be easily moved to a particular position or posture, where it will remain, without unwanted movement until it is deliberately moved again. 
     In keeping with an aspect of the invention, a preferred embodiment has just two basic types of parts. First, there is a rod having a ball on each end to create a shape similar to the shape of a dumbbell. A second discrete part is a sleeve in the form of a cylinder having a central bore with an undercut region near each end of the bore to form a socket. One ball of the dumbbell shaped part is pressed into the bore of a sleeve where the ball is captured in the undercut region in order to form a ball and socket joint. A series of these two types of ball and socket parts can be joined to make a linkage of any suitable length. 
     If the sleeve is to be manufactured at a reasonable cost and with a reasonable lifetime, the injection molded plastic part must be ejected from the mold without loss of its memory in the undercut area despite the fact that the still hot plastic part is pushed out of the mold. Over the lifetime of the sleeve, it should retain its plastic memory so that the joint retains both its freedom of movement and the degree of friction in the joint that preserves the posture of the joint until it is next moved deliberately. These features are accomplished by using a plastic which has a better memory and an appropriate flexibility characteristic so that it enables the sleeve to be ejected from the mold after the in-mold cooling and retains its memory afterward. The mold for making the sleeve opens in two steps, a first of which steps enables the plastic to cool somewhat inside the mold cavity before a pin is pulled from the undercut region as the mold opens completely in its second step. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred embodiment of the invention will become more apparent from the following specification taken with the attached drawings, in which: 
     FIG. 1 shows a ball and socket joint in partial cross-section made according to the inventive method; 
     FIG. 2 shows in cross-section a closed injection mold for making the socket shown in FIG. 1; 
     FIGS. 3A and 3B show the first two steps which partially open the mold and allow the pin to be pulled out from its undercut regions; 
     FIGS. 4A and 4B show the next two steps of knocking the injection molded sleeves out of the mold and pulling pins from the undercut regions; 
     FIG. 5A illustrates how a plurality of ball and socket joints are laid out preliminary to assembly of a structure; 
     FIG. 5B shows a layout similar to that of FIG. 5A in order to make a simple skeleton structure (here a tail assembly); 
     FIG. 6 shows the layout of the parts in a plate for automatically making a chain-like jointed support system by a two-step assembly process; 
     FIGS. 7A and 7B are perspective views showing an assembled jointed support system according to the present invention; 
     FIG. 8 is a front view which shows the structure of FIG. 7 being used as a skeleton to support a plush doll; 
     FIG. 9 is a side view which shows the doll of FIG. 8; 
     FIG. 10 is a perspective view of a rearing toy horse incorporating the jointed support system of the present invention in combination with other features; 
     FIG. 11 is the horse of FIG. 10 adjusted to place the horse in a walking posture; 
     FIG. 12 is a perspective view showing the jointed support system of the present invention inside the horse of FIGS. 10 and 11; 
     FIG. 13 shows a child&#39;s hand playing with the horse; 
     FIG. 14 is a perspective view of a sleeve and an annular contact element according to an embodiment of the invention comprising a joint switch; 
     FIG. 15 is a cross section of the sleeve of FIG. 14 with the annular contact mounted within the sleeve; 
     FIG. 16 is a cross section of a cooperating second part of a joint switch; 
     FIG. 17 is a cross section of an assembled joint switch shown in an orientation when the switch is open; and 
     FIG. 18 is a cross section of an assembled joint switch shown in an orientation when the switch is closed. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 is a plan view partly in cross-section showing a ball and socket (sleeve) in solid lines and illustrating the range of motion between the ball and the socket in dot-dashed lines. The angles of movement are within a conical region with an apex angle of 60° centered on the ball in the socket. In particular, the sleeve has an undercut region and a tight-fit feature is required for the socket in order to create enough friction to hold the ball in a position to which it is moved. When used as an internal support for a plush or stuffed toy, the resulting rigidity of the linkage inside the soft stuffing material, plush fabric, vinyl skin, and the like gives the toy the feel of real bones in the skeleton. 
     In greater detail, an embodiment of FIG. 1 illustrates the inventive ball and socket joint  20  which uses two discrete parts  22 ,  24 . Part  22  is a sleeve with a central bore  25  having therein undercut regions  26 ,  28  near each of its two ends. Part  24  has a shape somewhat like the shape of a dumbbell, i.e., a central rod  30  with balls  32 ,  34  on each end. The diameter of the balls is such that they may be pushed into bore  25  and captured in either of the undercut regions  26  or  28  with a grip that creates enough A friction to hold the ball in place and yet allows it to be moved, if desired. 
     A second sleeve  36  may be snapped over the ball  32  on the other end of rod  30 . Hence, a person may deliberately move part  24  relative to parts  22  and  36 . However, the parts will hold their relative posture until they are next deliberately moved due to the friction between the surface of each of the balls and the surface of the respective undercut regions. Dot-dashed lines are used in FIG. 1 to illustrate the range of movement between the parts  22 ,  24 , and  36 . Each of the balls permits a center line of the parts to form any convenient angle up to 60°, for example. 
     Turning now to FIGS. 14-18 an alternate ball and socket joint is disclosed in accordance with an alternate embodiment of the invention. This embodiment provides an electrical switch within the joint. The switch is configures so that movement of the components forming the joint actuate the switch. Sleeve  22  is formed substantially the same as shown in FIG.  1 . However, an annular contact ring  150  is fitted within the bore  25  of sleeve  22 . The contact ring  150  is made from a conductive material such as copper. An electrical lead preferably formed of insulated wire is soldered to contact ring  150  at solder joint  154 . The electrical lead  156  is threaded through a small exit bore  156  to communicate with external circuitry. FIG. 15 shows a cross section of sleeve  22  having the contact ring  150  mounted therein. The contact ring  150  is positioned within bore  25  adjacent the undercut region  26 . 
     FIG. 16 shows a modified second part  24  comprising a portion of the electrical switch. As with the previous embodiment, the modified second part  24  includes a central rod portion  30  with balls  32 ,  34  formed at each end. In the switch embodiment a bore  158  is formed axially through the length of the modified second part. Counter-sunk bores  160 ,  162  are formed at each end. A conductive shaft  164  is inserted through the axial bore  158  and extends at least into the counter sunk regions  160 ,  162 . A spring  166  is friction fit over a first end of conductive shaft  158  within counter sunk region  162  and extends out beyond the end of modified second part  24 . A contact head  168  is mounted at the distal end of spring  166 . At the opposite end of the shaft  164  an electrical lead  172  is soldered to the shaft. 
     The first and second parts  22 ,  24  may be joined as described above with regard to FIG. 1 to form ball and socket joint  20 . Ball  34  is inserted into undercut region  26  of sleeve  22 , allowing for angular motion of the second part  24  relative to the sleeve  22  in substantially every direction. A second sleeve  36  may be joined to the opposite end of the second piece  24  by inserting ball  32  into an undercut region formed within the second sleeve  36  similar to the under cut regions  26 ,  28  formed in sleeve  22 . This arrangement is shown in cross section in FIGS. 17 and 18. 
     When ball  32  is inserted within a second sleeve  36 , electrical lead  170  may be threaded through a small exit bore  172  formed in the side wall of second sleeve  36  to communicate with external electrical circuitry. At the opposite end of second part  24 , ball  34  is movably secured within the undercut region  26  at the end of sleeve  22 . Spring  166  extends from the end of second part  24  such that contact element  168 , mounted at the distal end of spring  166 , is positioned within the annular confines of contact ring  150 . Contact ring  150  and contact element  168  form the contact elements of an electrical switch across leads  152 ,  170 . 
     FIG. 17 shows the sleeve  22  and second part  24  oriented in a substantially axially aligned position. As can be seen, contact element  168  is spaced apart from contact ring  150 . In this position the electrical switch is open. When the second part  24  is angularly displaced relative to the sleeve  22  as shown in FIG. 18, however, the contact element  168  is pivoted against the contact ring  150 , thereby closing a circuit across leads  152 ,  170 . Due to the flexibility of spring  166 , contact element  168  may be held in engagement with contact ring  150  over a wide range of displacement angles of second part  24  relative to sleeve  22 , while simultaneously allowing substantially unrestricted movement of the second part  24  relative to the sleeve  22 . According to an embodiment of the invention the switch joint allows movement of the second part  24  of up to 30° from the axis in any direction. 
     When the joint switch just described is incorporated into the skeletal frame of a toy figure, an electrical signal which is passed when the switch closes may be used to activate a special feature or special effect. For example, the switch can be used to activate a speech function, or activate various sensors such as touch sensors, sound sensors, light sensors and others. 
     FIG. 2 is a cross-section elevation view illustrating an inventive, specially designed two-part injection mold for making the sleeve with an undercut socket on each end. The ejection core pins provide a delay when there is an ejection of the injection molded sleeves in order to solve the mold release problem resulting from the undercut region molded into the.sleeve at both ends of the socket. In FIG. 2, the two parts  50 ,  54  of the mold are shown in a closed position with the two mold cavities above and below the parting line for forming a single combined cavity for the injection molded sleeves such as  22 ,  36  (FIG. 1) when the combined cavity is filled with molten plastic resin. 
     Hence, FIG. 2 shows, a closed mold in the process of molding a part with an undercut region. More particularly, the injection molding machine (FIG. 2) has two platens  38 ,  40  which move toward or away from each other in order to close or open the mold in a two-step process. Here platen  38  is fixed and platen  40  moves. Next there are top and bottom clamping plates  42 ,  44 . These two plates  42 ,  44  are secured to their respective platens by hold-down clamps  46 ,  48 . Similar clamps (not shown) are present at the opposite ends of plates  42 ,  44 . 
     Plate  50  is a first cavity plate which has a first cavity for making an upper part of the injection molded sleeve  22 . Plate  54  is a second cavity plate having a second cavity for making the remainder of the sleeve  22 . When combined, these two cavities provide a single cavity having the complete contours of sleeve  22 . The gate  58  provides for injecting molten plastic into cavities at  52  and  56 . Plate  60  is a support plate. Plate  62  is an ejector retainer plate and plate  64  is an ejector plate. The ejector plate  64  contains two sleeves  67  in which lower core pins  68  slide, thereby forming two pin-in-a-sleeve combinations. Two upper core pins  66  slide in sleeves  65  located in the cavity plate  50 , also forming two pin-in-a-sleeve combinations. The pins  66 ,  68  are aligned to form bore  25  (FIG. 1) of the sleeve  22 . Each of the pins  66 ,  68  has an enlarged annular ring adjacent its end to form, the under cut regions  26 ,  28  in bore  25  of the sleeve  22 . Blocks  69 ,  70 ,  72  are spacers. 
     The injection mold shown in FIG. 2 can mold two sleeves simultaneously, the molten plastic being fed in via gate  58 . 
     FIG. 3A is similar to FIG. 2, except that it shows mold plates  50 ,  54  partially opened in step  1  in the process for ejecting the sleeve having an undercut region in the bore. In greater detail, the mold is partly opened as the lower mold part  54  begins to move downward (FIG. 3A) in the first step of the mold opening for ejecting the molded sleeve  22 . Two holes  69  allow a limited travel of pins  66  relative to movement of mold plates  50 ,  54  as they open to a partially open position. Due to the mold opening force on the molded sleeves  22 , the upper core pins  66  will travel downwardly as they are pulled by the molded sleeves  22  (FIG. 3A) from point “a” to point “b”. In this first step of the mold opening, the upper core pin  66  remains attached to the molded piece part  22  as the pin  66  moves downward because of a gripping force exerted by annular ridge  74  adjacent the end of core pin  66 , ridge  74  being trapped in the undercut socket  26  within bore  25 . That is, sleeve  22  initially grips pin  66  to pull the pin downward as the lower mold part  54  moves downward in the initial opening of the mold. 
     The travel excursion of pin  66  is limited by the depth of the hole  69  between points “a” and “b”. This travel provides a delay action which allows the injection molded sleeve  22  to leave the upper mold cavity and free itself from the hold of the upper mold cavity before the later mold release feature occurs as the sleeve will be stretched and enlarged when the annular ring of the core pin goes through the sleeve undercut region. 
     FIG. 3B shows a second step in the ejection process. The annular ridge  75  formed on the lower pin  68  is trapped in the undercut socket  28  of sleeve  22  to exert a gripping force on the sleeve  22  as the mold continues to open. Thus, as the mold opens further with lower mold part  54  continuing its downward movement, the molded sleeve  22  is pulled further downward by pin  68  off of upper pin  66 . The sleeve  22  is pulled off of pin  66  when the pin reaches point “b” in hole  69  and the downward travel of pin  66  is thus stopped. During this step, the undercut region  76  of the socket  22  is enlarged enough to pass over and let go of the annular ridge  74  at lower the end of upper core pin  66 . The injection part (sleeve)  22  now stays in the cavity in the other (lower) mold plate  50 . 
     After completing its downward movement, the ejector plate  64  begins to move upwardly as shown in FIG. 4A during the third step in the subject release process for injection molded parts with an undercut region. More particularly, holes  81  permit lower pin  68  to move a discrete distance as the ejector plate  64  moves upwardly. The lower core pin  68  moves from point “c” to point “d” which stops further pin travel. The injection molded sleeve part  22  thus leaves the lower half of the mold cavity, but stays on the lower core pin  68  owing to the undercut grip on the annular part  75  of pin  68 , as pin  68  travels upwardly in its travel from point “c” to point “d” in hole  81 . In step  4  (FIG.  4 B), the ejector plate  64  continues to move upwardly so that portion  83  of ejector sleeve  67  moves the ejector sleeve  67 , upwardly with respect to core pin  68 . The ejector sleeve  67  is disposed around core pin  68 . As a result of the action shown in FIG. 4B, the sleeve  67  pushes the injection molded part  22  off the end of core pin  68  and finally ejects it out of the mold cavity. 
     An important feature growing out of the delay action as the core pins  66 ,  68  and ejection sleeve  67  travel, during the steps between FIGS. 3 and 4, is that it lets the injection molded part  22  leave the mold cavity without destroying the undercut region of the sleeve  22  because the part is held on the core pins  66 ,  68 . That is, the core pins  66 ,  68  hold the molded part  22  for later release as it leaves the mold cavity in order to free itself from the hold of the mold cavity. The delay allows the injection molded part to be enlarged for releasing of the annular ridge  74  on the upper core pins  66  and the annular ridge  75  on the lower core pins  68  as they move through the undercut regions  26 ,  28  in the sleeve  22  without destroying the undercut region of the sleeve  22 . As can be seen in FIGS. 4A and 4B, the residual plastic  58 A formed at the gate  58  is discarded during the sleeve ejection. 
     Acetal copolymer (polyoxymethylene) is the most preferred plastic resin for producing the sleeve  22  with its undercut sockets. This material has a good memory and flexibility characteristic suitable for use by the inventive method of mold release because, by the time that the sleeve  22  is pulled off the core pins  66 ,  68 , the undercut region can stretch over the annular enlargement of the annular rings  74 ,  75  of the core pins without a loss of the plastic memory. The good memory and flexibility characteristic of the preferred plastic material are also desired for use as a socket in the ball and socket joint so that it can hold the ball firmly and provide reasonable friction for preventing random movement. 
     The preferred plastic material for making the “sleeve/socket” is, as follows: 
     Plastic resin name: Acetal Copolymer/Polyoxymethylene 
     Brand Name/Trademark: Celcon™ 
     Supplier: Polyplastics Co., Ltd. 
     Address: Kasumigaseki Bldg., 6th/Fl. 
     2-5 Kasumigaseki 3-chome 
     Chiyoda-ku 
     Tokyo, 100-6006 JAPAN 
     The manufacturer describes the specifications of this material as: 
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
               
               
                   
                 ASTM 
                   
                   
               
               
                 Property 
                 Test Method 
                 Units 
                 Co-polymer 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Specific Gravity 
                 D-792  
                 — 
                 1.41 
               
               
                 Melt Flow Index 
                 D-1238 
                 g/10 min 
                 9.0 
               
               
                 Tensile Strength, Yield 
                 D-638  
                 kg./cm 2   
                 607 
               
               
                 Tensile Elongation 
                 D-638  
                 % 
                 60 
               
               
                 Flexural Modulus 
                 D-790  
                 kg/cm 2   
                 25,880 
               
               
                 Izod Impact Strength 
                 D-256  
                 kg cm/cm 
                 6.9 
               
               
                 Heat Deflection Temp 
                 D-648  
                 ° C. 
                 110 
               
               
                 Vicat Softening Point 
                 D-1225 
                 ° C. 
                 162 
               
               
                 Water Absorption 
                 D-570  
                 % 
                 0.22 
               
               
                 Volume Resistivity 
                 D-257  
                 Ω cm 
                 10 14   
               
               
                 Surface Resistivity 
                 D-257  
                 Ω 
                 1.3 × 10 16   
               
               
                 Arc Resistivity 
                 D-495  
                 Sec 
                 240 
               
               
                 Rockwell Hardness 
                 D-785  
                 — 
                 M80 
               
               
                 FDA Compliance 
                 — 
                 — 
                 YES 
               
               
                 Flammability 
                 UL-94     
                 — 
                 94 HB 
               
               
                   
               
             
          
         
       
     
     FIGS. 5A and 5B are perspective views showing different injection molded joint parts, laid out and ready for final assembling. In greater detail, FIG. 5A shows a number of socket  22  and ball  24  joints laid out in the positions which they will occupy in the final skeleton of a plush doll, for example. In addition, FIG. 5A shows a head support part  80 , a shoulder simulation part  82 , and a base of spine part  84 . Part  84  optionally allows an addition of a tail when the skeleton is used as part of a stuffed animal. If the skeleton is used as part of a human doll, for example, part  84  remains as shown in FIG. 5A without any tail attachment. 
     Parts  86  are couplers which snap over mating couplers  88  in order to secure the remainder of the toy to the skeleton. For example, couplers  88  may be secured to the interior of a stuffed animal body. 
     FIG. 5B is intended to show that any suitable part may be made by the inventive method. As shown here, the part is a tail for the skeleton of FIG. 5A; however, it could also be part of a child&#39;s necklace, or any other suitable device. In this particular disclosure, part  90  is a coupler which slips into a window  92  of the part  84  at the base of the spine. 
     FIGS. 5A and 5B include a series of arrows E-I which indicate directions in which the loose parts of FIG. 5 are to be pushed in order to assemble them into the final form of FIG.  7 . For example, if the loose parts are simultaneously pushed in directions E, F, the arms and shoulder parts are joined. If the loose parts are simultaneously pushed in directions G and H, the head and spine parts are joined. 
     FIG. 6 is a perspective view which shows an automatic assembly machine for joining the loose joint parts by placing them in a fixture which is operated by a pneumatic system. The fixture has a bottom part  93 , a top part  94  and four slide pieces  96 - 102  operated by individually associated pneumatic cylinders  104 - 110  mounted around the fixture bottom part  94 . In greater detail, the top and bottom parts  93 ,  94  are simple, preferably metal, parts having grooves formed therein which follow the lines of a desired end product, such as the skeleton of FIG.  7 A. 
     FIG. 6 shows the loose parts of FIGS. 5A and 5B laid out in the grooves in bottom plate  93 . The top plate  94  has complementary grooves which enclose the loose parts after plate  94  closes over plate  93 . 
     First, after the two plates  93 ,  94  close, pneumatic cylinders  104 ,  108  push blocks  96 ,  100  inwardly (Motion 1) which assembles the head and spine parts by pushing them together as described above in connection with FIG.  5 A. Next, pneumatic cylinders  106 ,  110  push blocks  98 ,  102  inwardly (Motion 2) which similarly pushes the parts of the arms and tail together. 
     Briefly in review, all joint parts are placed in cavities formed by grooves in the fixture bottom part. By using pneumatic power, the fixture top part moves down and makes contact with the fixture bottom part, applying a suitable force in the process. All joint parts are loosely kept in place inside the cavities formed in the top and bottom parts, with a limited space tolerance for enabling further operations. 
     The pneumatic cylinders  104 ,  108  simultaneously push (Motion 1) the head part and the part at the end of the back bone with appropriate force in order to snap and interconnect all the joint parts. Then, the pneumatic cylinders  104 ,  108  return to their original starting positions. Next, the same actions take place as pneumatic cylinders  106 ,  108  push from opposite, sides of the bottom part in order to interconnect the arms, legs and tail joint parts (Motion  2 ), and then return to their original starting positions. Thereafter, the fixture top part  94  moves up and provides space for removing the assembled skeleton. 
     This fixture is not limited to skeletons, but may be used for interconnecting any of many different types of loose,joint parts in order to avoid excessive labor costs. Hence, this automatic assembly machine is not limited to assembling parts having the same configurations. Different cavity designs may be formed in different fixture top parts and fixture bottom parts to enable an assembly of many different configurations of linkage, at a very low cost as compared to the cost of a molding cavity. 
     When the top fixture part  94  is lifted off the bottom fixture part  93 , the jointed support systems of FIGS. 7A and 7B are removed already assembled from the grooves in bottom fixture part  93 . 
     FIG. 8 is a front elevation view showing a stuffed plush/vinyl doll or toy supported by a skeleton comprising the molded jointed linkage support system. FIG. 9 is a side elevation view of a skeleton in side a stuffed plush/vinyl animal body with a tail attached thereto. Snap couplers  86 ,  88  anchor the skeleton to the inside of the stuffed toy. 
     The principles of the invention may be used to make almost any suitable kind of toy or doll that can be imagined. By way of example, FIGS. 10 and 11 show a toy horse with a plush body and with a shaggy mane  122  and tail  124  which light when brushed. In FIG. 10, the skeleton has been manipulated so that the horse is in a rearing posture. In FIG. 11, the skeleton has been manipulated so that the horse is walking. 
     FIG. 12 shows the skeleton  120  of the horse without the plush body. The forelock  121 , mane  122 , and tail  124  are optical fiber strands. A battery box  126  is adapted to receive two AA battery cells. A pair of lamp bulbs  128 ,  130  are positioned to light the optical fiber strands in the forelock, mane and tail, respectively. Each of these lamp bulbs is coupled to the batteries in box  126  via a pair of magnetically operated switches  132 ,  134 , respectively. 
     The flexibly mounted eyes  136 ,  138  have a magnetic material associated therewith so that they will animate when a magnet is brought near them. 
     FIG. 13 illustrates the operation of the toy of FIGS. 10-12. The hand  140  is holding a magnetic brush  142  which is brushing the horse&#39;s mane, thereby operating magnetic switch  132  and causing bulb  128  to light the optical fiber strands so that the mane glows. Also, the eye  138  moves and appears to be watching the motion of the brush  142 . In a similar manner, the tail will glow when the magnetic brush  142  is brought near switch  134 . 
     Those who are skilled in the art will readily perceive modifications which fall within the scope and spirit of the invention. Therefore, the appended claims are to be construed to cover all equivalent structures.