CA1177213A - Hydraulically actuated injection molding system - Google Patents
Hydraulically actuated injection molding systemInfo
- Publication number
- CA1177213A CA1177213A CA000398866A CA398866A CA1177213A CA 1177213 A CA1177213 A CA 1177213A CA 000398866 A CA000398866 A CA 000398866A CA 398866 A CA398866 A CA 398866A CA 1177213 A CA1177213 A CA 1177213A
- Authority
- CA
- Canada
- Prior art keywords
- valve pin
- mouth
- cylinder
- piston
- injection molding
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000001746 injection moulding Methods 0.000 title claims abstract description 13
- 239000000155 melt Substances 0.000 claims description 9
- 238000000465 moulding Methods 0.000 claims description 3
- 238000005259 measurement Methods 0.000 abstract description 8
- 206010013642 Drooling Diseases 0.000 abstract description 2
- 208000008630 Sialorrhea Diseases 0.000 abstract description 2
- 230000035508 accumulation Effects 0.000 abstract 1
- 238000009825 accumulation Methods 0.000 abstract 1
- 238000009434 installation Methods 0.000 abstract 1
- 239000012530 fluid Substances 0.000 description 7
- 238000000034 method Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 229910000881 Cu alloy Inorganic materials 0.000 description 1
- 229910001069 Ti alloy Inorganic materials 0.000 description 1
- DMFGNRRURHSENX-UHFFFAOYSA-N beryllium copper Chemical compound [Be].[Cu] DMFGNRRURHSENX-UHFFFAOYSA-N 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/26—Moulds
- B29C45/27—Sprue channels ; Runner channels or runner nozzles
- B29C45/28—Closure devices therefor
- B29C45/2806—Closure devices therefor consisting of needle valve systems
- B29C45/281—Drive means therefor
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Injection Moulding Of Plastics Or The Like (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
This invention relates to a hydraulically actuated valve gated injection molding system. The valve pin actuating mechanism has a piston which engages the driven end of the valve pin and reciprocates in a cylinder in alignment with the valve pin. The cylinder is bolted directly to the back plate and has a mouth which is also in alignment with the valve pin and is sealed by a separately removable cap. In order to compensate for accumulations of tolerances and have the valve pin seat accurately to avoid drooling or breakage of the seat, it is desirable to accurately measure the necessary length of valve pin after the remainder of the system has been assembled. The mouth of the cylinder is larger in diameter than the piston to allow these measurements to be taken, the proper length valve pin to be attached to the piston outside the cylinder, and the assembly to then be inserted through the mouth. This structure provides for accurate measurement of the necessary length of valve pin after assembly of the rest of the system, as well as for convenient installation of the valve pin without disassembling the system.
This invention relates to a hydraulically actuated valve gated injection molding system. The valve pin actuating mechanism has a piston which engages the driven end of the valve pin and reciprocates in a cylinder in alignment with the valve pin. The cylinder is bolted directly to the back plate and has a mouth which is also in alignment with the valve pin and is sealed by a separately removable cap. In order to compensate for accumulations of tolerances and have the valve pin seat accurately to avoid drooling or breakage of the seat, it is desirable to accurately measure the necessary length of valve pin after the remainder of the system has been assembled. The mouth of the cylinder is larger in diameter than the piston to allow these measurements to be taken, the proper length valve pin to be attached to the piston outside the cylinder, and the assembly to then be inserted through the mouth. This structure provides for accurate measurement of the necessary length of valve pin after assembly of the rest of the system, as well as for convenient installation of the valve pin without disassembling the system.
Description
~77Z~3 This invention relates to valve gated injection molding and more particularly to an improved hydraulically actuated system which provides direct separate and independent access to the valve pin and piston area.
~ Iydraulically actuated valve gated injection molding sys-tems with pistons which reciprocate in cylinders in alignment with the valve pins are well known. Normally, each system has a manifold plate which extends between a heater nozzle seated in a cavity plate and a back plate which receives the valve pin actuating mechanism. While all of these components are made with extremely close tolerances to predetermined dimensions, it has often been found that when they are assembled the valve pin does not seat in the gate with sufficient accuracy in the closed position. If the valve pin is shorter in length than that required by the tightly assembled components, the gate will-not be completely closed allowing the melt to leak or drool or leave an unsightly gate mark. On the other hand, if the valve pin is even slightly longer than required so that it hits the gate before the piston comes up against its mechanical stop, the very ~high hydraulic actuating pressures required will quickly cause the gate to break. Thus, extreme accuracy is required and the problem is much worse with hydraulically actuated systems than pneumatically actuated systems because the hydraulic fluid is not compressible resulting in very high impact stresses.
In the past, attempts to overcome this problem have included lapping the tip end of the valve pin when it is seated in the gate to adjust its effective length. However, this cannot really be effective unless the combined dimension of the operating assembly is known. This is, of course, dependent upon assembly ~77Z~3 1 procedures and operating conditions such as temperature, as well as upon manufacturing tolerances of the various components.
Consequently, it has become necessary or at least highly desirable to take measurements during bench tests following assembly to determine the exact length of valve pin required. However, in the past, this procedure has suffered the disadvantage that the structure did not provide access for sufficiently accurate measurements to be taken without partially disassembling or at least loosening some of the components such as the cylinder whose 1 n relationship determine the very dimensions to be measured.
Accordingly, the practice has arisen of measurements being taken and then approximations being made to which the lengths of the valve pins are adjusted with the result that an unacceptable number of the systems eventually malfunction due to the dimensions not being sufficiently accurate.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to at least partially overcome these problems by providing a hydraulically actuated valve gated injection molding system with an improved structure which provides for more convenient and accurate measurement of the length of valve pin required.
To this end, in one of its aspects, the invention provides a hydraulically actuated valve gated injection molding system having a heater nozzle seated in a cooled cavity plate, a gate through the cavity plate leading to a cavity, an elongated valve pin which reciprocates in a bore in the heater nozzle between open and closed positions, the valve pin having a driven end and a tip end which seats in the gate in the closed position, a melt passage which extends through the heater nozzle and conveys pressurized melt from a molding machine to the gate, and i~77Z~3 1 valve pin actuating mechanism which includes a hydraulically driven piston which operatively engages the driven end of the valve pin and reciprocates in a cylinder seated in a back plate, the improvement wherein the hydraulic cylinder is secured directly to the back plate and has a mouth securely sealed by a cap, the mouth being centrally located in alignment with the valve pin, the cap being removable from the mouth whereby the valve pin may be conveniently installed and removed through the mouth after the rest of the system has been assembled.
Further objects and advantages of the invention will appear from the following description taken together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a sectional view of a portion of a valve gated injection molding system according to a preferred embodiment of the invention;
Figure 2 is an exploded isometric view of a portion of the system shown in Figure l;
Figure 3 is an enlarged sectional view of a portion of the system shown in Figure l; and, Figures4 and 5 are partially schematic views of the system shown in Figure 1 illustrating the provision for measure-ments being taken.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Reference is first made to Figure 1 which shows one heater nozzle 10 of a multi-cavity hydraulically actuated valve gated injection molding system seated in a cavity plate 12.
A manifold 14 positioned by locating ring 16 extends between the heater nozzle 10 and a ~ack plate 18. The heater nozzle 10 has ~77Z~3 1 a central bore 20 through which extends a valve pin 22 having a driven end 24 and a tip end 26. Hydraulically driven actuating mechanism 28 reciprocates the valve pin 22 in the bore 20 between an open position and the closed position shown in which the tip end 26 is seated in a gate 30 in the cavity plate 12 leading to the cavity 32. A melt passage 34 branches out from a recessed inlet 36 through the manifold 14 and extends through ~the heater nozzle 10 to the gate 30. As may be seen the melt passage 34 through the heater nozzle is provided around the valve pin 22 by an enlarged portion 38 of the bore 20 In this embodiment, the melt passage 34 joins the bore 20 in a stainless steel bushing seal 40 which is seated in the heater nozzle 10 formed of a beryllium copper alloy as descrlbed in the applicant's U.S.
patent 4,026,518 which issued May 31, 1977. The bushing seal 40 has a circumferential opening 42 which extends around the valve pin 22 and has a vent to atmosphere (not shown) to provide for the escape of harmful gases and fluids which seep out around the valve pin.
The heater nozzle 10 has an electr.ic heating element 44 which is cast into it and receives power through terminals 46 to provide the heat necessary to maintain the melt at the desired temperature. On the other hand, the cavity plate 12 a.round the cavity 32 and the back plate 18 are cooled by cooling elements 48. Thus, the hot manifold 14 and heater nozzle are separated from the cool cavity plate 12 and back plate 18 by an insulative air space 50 provided by the locating ring 16 and the insulation bushing 52 which supports the heater nozzle 10 in the cavity plate 12. The air space or gap 50 is bridged around the gate 30 by a hollow cylindrical nozzle seal 54 which is formed of a titanium alloy and seats in the heater nozzle 10 as described ~77Z13 1 in the applicant's U.S. patent 4,043,740 which issued August 23, 1977. The manifold 14 and the heater nozzle 10 are secured by bolts 56 which extend through them into the cavity plate 12 and the back plate is, in turn, secured in pLace by bolts 58.
The actuating mechanism 28, which is clearly shown in Figures 2 and 3, has a hydraulically driven piston 60 which reciprocates in a cylinder 62. The cylinder 62 is seated in an opening through the back plate 18 in alignment with the valve pin 22 and is secured in position by bolts 64 which extend through a collar portion 66 and into the back plate 18. The cylinder 62 has a threaded mouth 68 which also is in alignment with the valve pin 22 and which is larger in diameter than the piston 60 to allow the piston to pass through it. The mouth 68 of the cylinder 62 is normally seale.d by a circular cap 70 which screws into it and is tightened by a special forked wrench (not shown) which has pins that fit into the small holes 72 in the top of the cap 70. The piston 60 fits inside the cylinder 62 and, in turn, receives the valve pin 22 which extends through a central hole 74 with its enlarged head or driven end 24 supported against a shoulder 76. The valve pin 22 is secured to the piston 60 by a plug 78 which is screwed into a well 80 in the piston and tightened against a washer 82 on the head 24 of the valve pin 22 using a hexagonal wrench which fits into socket 84. The piston 60 is driven by a controlled source of pressurized hydraulic fluid (not shown) which is connected on opposite sides of the piston 60 by hydraulic fluid ducts 86. A high temperature seal is provided by a V-shaped flexible ring 88 which is seated in the cylinder 62 and extends around the piston 60 to prevent the escape of the pressurized hydraulic fluid. Numerous other O-rings 90 are also provided between the cylinder 62 and the back ~77Z~3 1 plate 18, between the piston 60 and the cylinder and around the cap 70 and the plug 7~ to reduce leakage of the pressurized hydraulic fluid.
In use, following assembly of the system, electrical power is applied to the terminals 46 of the heating element 44 to heat the heater nozzle 10 up to operating temperature~
Pressurized melt from the molding machine is then introduced into the melt passage 34 and controlled hydraulic pressure is applied to the actuating mechanism according to a predetermined cycle in a conventional manner. After sufficient melt has been injected to fill the cavity 34 and the high injection pressure held for a short period to pack, the hydraulic pressure is applied to reciprocate the valve pin 22 and piston 60 to the closed position in which the valve pin tip end 26 is seated in the gate 30.
The melt pressure is then reduced and the position held for a cooling period before the mold is opened for ejection. After the mold is closed again, hydraulic pressure is applied to reciprocate the valve pin 22 to the open position and the high injection pressure is reapplied. ~s may be seen, the actuating mechanism 28 has positive stops in that the piston 60 abuts against the cap 70 in the open position and against a shoulder 91.
However, as mentioned above, as the valve pin 22 is securely connected to the piston 60, and the hydraulic fluid is essentially non-compressible, if the valve pin is too long it will impact against the valve gate 30 rather than shoulder 90 on closing resulting in considerable danger that the cavity plate 12 will eventually break down in the gate area. Conversely, if the valve pin is made too short it will not seat properly in the closed position, resulting in leakage or drooling when the mold is opened or generally leaves an unsightly gate mark.
~77Z13 1 Therefore, it is necessary to measure each system when it is pneumatically bench tested and then adjust the length of a valve pin 22 to exactly match the requirements of that p~rticular location in the system, with allowance for heat expansion for that particular applîcation. As shown in Figures 4 and 5, this is carried out by assembling the system according to operational requirements except that the valve pin 22 and the plug 78 which attaches it to the piston 60 are not inserted.
As may be seen, the cylinder 62 is actually bolted in position and it is important that cylinder bolts 64 as well as the other bolts 56 and 58 which hold the mold together are tightened to the required torque to closely simulate actual operating conditions. A digital depth micrometer 92 ~or other suitable instrument) is then inserted through the mouth 68 of the cylinder 62 to accurately measure dimension "a" into the shoulder 76 which supports the head 24 of the valve pin 22. A block 94 is then placed over the gate 30 flush with the cavity plate 12 and dimension "b" into it is accurately measured. The difference between dimensions "a" and "b" determines the necessary length of the valve pin 22 from the base of the head and a valve pin having the appropriate length is then selected or made. In view of the fact that the mouth 68 of the cylinder 62 is larger in diameter than the piston 60, it is not necessary to disassemble the system to add the valve pin. This is done by removing the piston 60 through the mouth 68 of the cylinder, inserting the valve pin through the central hole 74 in the piston and screwing the plug 78 in to hold it. It is, of coursQ, necessary to remove the piston 60 from the cylinder to do this or else provide some means by which the piston 60 may be held against rotation while the plug is tightened. The assembled piston 60 and valve pin 22 are then inserted through the mouth 68 of the cylinder 62, the cap 70 tightened into place and the bench test, either ~7-i~77Z~3 l pneumatic or hydraulic, proceeded with. Thus, a relatively easy and convenient procedure is provided for carrying out these measurements after most of the system has been assembled and it is not necessary to adjust the assembl~ of that portion of the system after doing so.
Although the description of this injection molding system has been given with respect to a particular embodiment of the invention, it is not to be construed in a limiting sense.
Variations and modifications will occur to those skilled in the art. For instance, different types of removable caps could be provided and other structures could be provided for connecting the valve pin to the piston. For a definition of the invention, reference is made to the attached claims.
~ Iydraulically actuated valve gated injection molding sys-tems with pistons which reciprocate in cylinders in alignment with the valve pins are well known. Normally, each system has a manifold plate which extends between a heater nozzle seated in a cavity plate and a back plate which receives the valve pin actuating mechanism. While all of these components are made with extremely close tolerances to predetermined dimensions, it has often been found that when they are assembled the valve pin does not seat in the gate with sufficient accuracy in the closed position. If the valve pin is shorter in length than that required by the tightly assembled components, the gate will-not be completely closed allowing the melt to leak or drool or leave an unsightly gate mark. On the other hand, if the valve pin is even slightly longer than required so that it hits the gate before the piston comes up against its mechanical stop, the very ~high hydraulic actuating pressures required will quickly cause the gate to break. Thus, extreme accuracy is required and the problem is much worse with hydraulically actuated systems than pneumatically actuated systems because the hydraulic fluid is not compressible resulting in very high impact stresses.
In the past, attempts to overcome this problem have included lapping the tip end of the valve pin when it is seated in the gate to adjust its effective length. However, this cannot really be effective unless the combined dimension of the operating assembly is known. This is, of course, dependent upon assembly ~77Z~3 1 procedures and operating conditions such as temperature, as well as upon manufacturing tolerances of the various components.
Consequently, it has become necessary or at least highly desirable to take measurements during bench tests following assembly to determine the exact length of valve pin required. However, in the past, this procedure has suffered the disadvantage that the structure did not provide access for sufficiently accurate measurements to be taken without partially disassembling or at least loosening some of the components such as the cylinder whose 1 n relationship determine the very dimensions to be measured.
Accordingly, the practice has arisen of measurements being taken and then approximations being made to which the lengths of the valve pins are adjusted with the result that an unacceptable number of the systems eventually malfunction due to the dimensions not being sufficiently accurate.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to at least partially overcome these problems by providing a hydraulically actuated valve gated injection molding system with an improved structure which provides for more convenient and accurate measurement of the length of valve pin required.
To this end, in one of its aspects, the invention provides a hydraulically actuated valve gated injection molding system having a heater nozzle seated in a cooled cavity plate, a gate through the cavity plate leading to a cavity, an elongated valve pin which reciprocates in a bore in the heater nozzle between open and closed positions, the valve pin having a driven end and a tip end which seats in the gate in the closed position, a melt passage which extends through the heater nozzle and conveys pressurized melt from a molding machine to the gate, and i~77Z~3 1 valve pin actuating mechanism which includes a hydraulically driven piston which operatively engages the driven end of the valve pin and reciprocates in a cylinder seated in a back plate, the improvement wherein the hydraulic cylinder is secured directly to the back plate and has a mouth securely sealed by a cap, the mouth being centrally located in alignment with the valve pin, the cap being removable from the mouth whereby the valve pin may be conveniently installed and removed through the mouth after the rest of the system has been assembled.
Further objects and advantages of the invention will appear from the following description taken together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a sectional view of a portion of a valve gated injection molding system according to a preferred embodiment of the invention;
Figure 2 is an exploded isometric view of a portion of the system shown in Figure l;
Figure 3 is an enlarged sectional view of a portion of the system shown in Figure l; and, Figures4 and 5 are partially schematic views of the system shown in Figure 1 illustrating the provision for measure-ments being taken.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Reference is first made to Figure 1 which shows one heater nozzle 10 of a multi-cavity hydraulically actuated valve gated injection molding system seated in a cavity plate 12.
A manifold 14 positioned by locating ring 16 extends between the heater nozzle 10 and a ~ack plate 18. The heater nozzle 10 has ~77Z~3 1 a central bore 20 through which extends a valve pin 22 having a driven end 24 and a tip end 26. Hydraulically driven actuating mechanism 28 reciprocates the valve pin 22 in the bore 20 between an open position and the closed position shown in which the tip end 26 is seated in a gate 30 in the cavity plate 12 leading to the cavity 32. A melt passage 34 branches out from a recessed inlet 36 through the manifold 14 and extends through ~the heater nozzle 10 to the gate 30. As may be seen the melt passage 34 through the heater nozzle is provided around the valve pin 22 by an enlarged portion 38 of the bore 20 In this embodiment, the melt passage 34 joins the bore 20 in a stainless steel bushing seal 40 which is seated in the heater nozzle 10 formed of a beryllium copper alloy as descrlbed in the applicant's U.S.
patent 4,026,518 which issued May 31, 1977. The bushing seal 40 has a circumferential opening 42 which extends around the valve pin 22 and has a vent to atmosphere (not shown) to provide for the escape of harmful gases and fluids which seep out around the valve pin.
The heater nozzle 10 has an electr.ic heating element 44 which is cast into it and receives power through terminals 46 to provide the heat necessary to maintain the melt at the desired temperature. On the other hand, the cavity plate 12 a.round the cavity 32 and the back plate 18 are cooled by cooling elements 48. Thus, the hot manifold 14 and heater nozzle are separated from the cool cavity plate 12 and back plate 18 by an insulative air space 50 provided by the locating ring 16 and the insulation bushing 52 which supports the heater nozzle 10 in the cavity plate 12. The air space or gap 50 is bridged around the gate 30 by a hollow cylindrical nozzle seal 54 which is formed of a titanium alloy and seats in the heater nozzle 10 as described ~77Z13 1 in the applicant's U.S. patent 4,043,740 which issued August 23, 1977. The manifold 14 and the heater nozzle 10 are secured by bolts 56 which extend through them into the cavity plate 12 and the back plate is, in turn, secured in pLace by bolts 58.
The actuating mechanism 28, which is clearly shown in Figures 2 and 3, has a hydraulically driven piston 60 which reciprocates in a cylinder 62. The cylinder 62 is seated in an opening through the back plate 18 in alignment with the valve pin 22 and is secured in position by bolts 64 which extend through a collar portion 66 and into the back plate 18. The cylinder 62 has a threaded mouth 68 which also is in alignment with the valve pin 22 and which is larger in diameter than the piston 60 to allow the piston to pass through it. The mouth 68 of the cylinder 62 is normally seale.d by a circular cap 70 which screws into it and is tightened by a special forked wrench (not shown) which has pins that fit into the small holes 72 in the top of the cap 70. The piston 60 fits inside the cylinder 62 and, in turn, receives the valve pin 22 which extends through a central hole 74 with its enlarged head or driven end 24 supported against a shoulder 76. The valve pin 22 is secured to the piston 60 by a plug 78 which is screwed into a well 80 in the piston and tightened against a washer 82 on the head 24 of the valve pin 22 using a hexagonal wrench which fits into socket 84. The piston 60 is driven by a controlled source of pressurized hydraulic fluid (not shown) which is connected on opposite sides of the piston 60 by hydraulic fluid ducts 86. A high temperature seal is provided by a V-shaped flexible ring 88 which is seated in the cylinder 62 and extends around the piston 60 to prevent the escape of the pressurized hydraulic fluid. Numerous other O-rings 90 are also provided between the cylinder 62 and the back ~77Z~3 1 plate 18, between the piston 60 and the cylinder and around the cap 70 and the plug 7~ to reduce leakage of the pressurized hydraulic fluid.
In use, following assembly of the system, electrical power is applied to the terminals 46 of the heating element 44 to heat the heater nozzle 10 up to operating temperature~
Pressurized melt from the molding machine is then introduced into the melt passage 34 and controlled hydraulic pressure is applied to the actuating mechanism according to a predetermined cycle in a conventional manner. After sufficient melt has been injected to fill the cavity 34 and the high injection pressure held for a short period to pack, the hydraulic pressure is applied to reciprocate the valve pin 22 and piston 60 to the closed position in which the valve pin tip end 26 is seated in the gate 30.
The melt pressure is then reduced and the position held for a cooling period before the mold is opened for ejection. After the mold is closed again, hydraulic pressure is applied to reciprocate the valve pin 22 to the open position and the high injection pressure is reapplied. ~s may be seen, the actuating mechanism 28 has positive stops in that the piston 60 abuts against the cap 70 in the open position and against a shoulder 91.
However, as mentioned above, as the valve pin 22 is securely connected to the piston 60, and the hydraulic fluid is essentially non-compressible, if the valve pin is too long it will impact against the valve gate 30 rather than shoulder 90 on closing resulting in considerable danger that the cavity plate 12 will eventually break down in the gate area. Conversely, if the valve pin is made too short it will not seat properly in the closed position, resulting in leakage or drooling when the mold is opened or generally leaves an unsightly gate mark.
~77Z13 1 Therefore, it is necessary to measure each system when it is pneumatically bench tested and then adjust the length of a valve pin 22 to exactly match the requirements of that p~rticular location in the system, with allowance for heat expansion for that particular applîcation. As shown in Figures 4 and 5, this is carried out by assembling the system according to operational requirements except that the valve pin 22 and the plug 78 which attaches it to the piston 60 are not inserted.
As may be seen, the cylinder 62 is actually bolted in position and it is important that cylinder bolts 64 as well as the other bolts 56 and 58 which hold the mold together are tightened to the required torque to closely simulate actual operating conditions. A digital depth micrometer 92 ~or other suitable instrument) is then inserted through the mouth 68 of the cylinder 62 to accurately measure dimension "a" into the shoulder 76 which supports the head 24 of the valve pin 22. A block 94 is then placed over the gate 30 flush with the cavity plate 12 and dimension "b" into it is accurately measured. The difference between dimensions "a" and "b" determines the necessary length of the valve pin 22 from the base of the head and a valve pin having the appropriate length is then selected or made. In view of the fact that the mouth 68 of the cylinder 62 is larger in diameter than the piston 60, it is not necessary to disassemble the system to add the valve pin. This is done by removing the piston 60 through the mouth 68 of the cylinder, inserting the valve pin through the central hole 74 in the piston and screwing the plug 78 in to hold it. It is, of coursQ, necessary to remove the piston 60 from the cylinder to do this or else provide some means by which the piston 60 may be held against rotation while the plug is tightened. The assembled piston 60 and valve pin 22 are then inserted through the mouth 68 of the cylinder 62, the cap 70 tightened into place and the bench test, either ~7-i~77Z~3 l pneumatic or hydraulic, proceeded with. Thus, a relatively easy and convenient procedure is provided for carrying out these measurements after most of the system has been assembled and it is not necessary to adjust the assembl~ of that portion of the system after doing so.
Although the description of this injection molding system has been given with respect to a particular embodiment of the invention, it is not to be construed in a limiting sense.
Variations and modifications will occur to those skilled in the art. For instance, different types of removable caps could be provided and other structures could be provided for connecting the valve pin to the piston. For a definition of the invention, reference is made to the attached claims.
Claims (4)
1. In a hydraulically actuated valve gated injection molding system having a heater nozzle seated in a cooled cavity plate, a gate through the cavity plate leading to a cavity, an elongated valve pin which reciprocates in a bore in the heater nozzle between open and closed positions, the valve pin having a driven end and a tip end which seats in the gate in the closed position, a melt passage which extends through the heater nozzle and conveys pressurized melt from a molding machine to the gate, and valve pin actuating mechanism which includes a hydraulically driven piston which operatively engages the driven end of the valve pin and reciprocates in a cylinder seated in a back plate, the improvement wherein;
the hydraulic cylinder is secured directly to the back plate and has a mouth securely sealed by a cap, the mouth being centrally located in alignment with the valve pin, the cap being removable from the mouth whereby the valve pin may be conveniently installed and removed through the mouth after the rest of the system has been assembled.
the hydraulic cylinder is secured directly to the back plate and has a mouth securely sealed by a cap, the mouth being centrally located in alignment with the valve pin, the cap being removable from the mouth whereby the valve pin may be conveniently installed and removed through the mouth after the rest of the system has been assembled.
2. An injection molding system as claimed in claim 1 wherein the mouth of the cylinder is larger in diameter than the piston, whereby the valve pin and the piston may be conveniently installed and removed through the mouth after the rest of the system has been assembled.
3. An injection molding system as claimed in claim 2 wherein the mouth of the cylinder and the cap are threaded and the cap has wrench engaging means whereby the cap may be screwed into a sealed position in the mouth and conveniently removed therefrom.
4. An injection molding system as claimed in claim 3 wherein the cylinder is bolted to the back plate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000398866A CA1177213A (en) | 1982-03-19 | 1982-03-19 | Hydraulically actuated injection molding system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000398866A CA1177213A (en) | 1982-03-19 | 1982-03-19 | Hydraulically actuated injection molding system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1177213A true CA1177213A (en) | 1984-11-06 |
Family
ID=4122352
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000398866A Expired CA1177213A (en) | 1982-03-19 | 1982-03-19 | Hydraulically actuated injection molding system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1177213A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3609054A1 (en) * | 1985-04-30 | 1986-10-30 | Jobst Ulrich Georgetown Ontario Gellert | INJECTION MOLDING SYSTEM |
| US4747770A (en) * | 1986-10-17 | 1988-05-31 | Mold-Masters Limited | Fluid cooled hydraulic actuating mechanism for injection molding |
| US4964795A (en) * | 1985-12-09 | 1990-10-23 | Tooman Patrick A | Manifold assembly for plastic injection molding |
| CN113814701A (en) * | 2021-10-25 | 2021-12-21 | 山东里能鲁西矿业有限公司 | Mining coal mining hydraulic pin dismounting device and matched dismounting method |
-
1982
- 1982-03-19 CA CA000398866A patent/CA1177213A/en not_active Expired
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3609054A1 (en) * | 1985-04-30 | 1986-10-30 | Jobst Ulrich Georgetown Ontario Gellert | INJECTION MOLDING SYSTEM |
| US4669971A (en) * | 1985-04-30 | 1987-06-02 | Gellert Jobst U | Valve gated probe |
| US4964795A (en) * | 1985-12-09 | 1990-10-23 | Tooman Patrick A | Manifold assembly for plastic injection molding |
| US4747770A (en) * | 1986-10-17 | 1988-05-31 | Mold-Masters Limited | Fluid cooled hydraulic actuating mechanism for injection molding |
| CN113814701A (en) * | 2021-10-25 | 2021-12-21 | 山东里能鲁西矿业有限公司 | Mining coal mining hydraulic pin dismounting device and matched dismounting method |
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