Description:1 TITLE OF INVENTION
Positioning Fixture for a Surface Conversion Process of Metallic Components
2 FIELD OF INVENTION
The invention relates to surface engineering, tool engineering & mechanical engineering, in general and in particular to a positioning fixture used in a surface conversion process in which the components are required to be positioned at pre-defined holding stations with sufficient firmness & safe spatial separation.
3 BACKGROUND OF INVENTION
Aerospace Industry involve various critical surface treatment processes involving the interactions among electrolytic chemicals & metallic surfaces for enhancing the specific surface characteristics like corrosion resistance, wear resistance & aesthetic appeal. Components are often required to be immersed inside the electro-chemical process baths of particular concentrations for pre-defined cycles with specific gradients of voltages &/or temperature for specific durations. In general, custom fixtures are designed for specific configurations of aerospace components, for loading the charges into the process baths. Hence, along with the components, these custom fixtures also undergo the same process cycles.
Fixture Life and usability is limited to a certain number of process cycles which depends on the fixture design, material of construction, process cycles and the thermal fatigue experienced. Periodic maintenance & repairs of the fixtures are carried out to extend the life of the fixtures by correcting the thermal warpages, structural distortions & welding failures, wherever possible.
The surface conversion process under discussion consists of a large metallic tank in which electrolyte solution of specific concentration is filled. The top side of the surface conversion bath tank is open for loading/unloading of the charge. A removable long electrical conducting bar [B] is placed on a conducting holder which in turn is connected to electricity source. Metallic components like Sheet Metal stiffeners, splice plates, machined stringers etc. are required to be suspended into the bath from the said electrical conducting bar by means of an electrical conducting suspension media to undergo pre-defined process cycle with set parameters.
Conventionally, for clamping conductive metallic wires, arms, trays, fixtures are used to firmly hold the metallic components while immersing them in the electrolytic surface conversion baths. The contact areas between the component and the fixture elements doesn’t undergo the electro-chemical process resulting in surface defects. However, these contacts are essential to hold the component safely in the bath, while the contact area shall be minimal to avoid any undesirable surface defects & subsequent surface repairs.
To ensure safe loading & unloading of the charges, it is a general practice to load the charges in batches of small quantities with significant distances in between them. This is to avoid the possible collisions/contacts among the charges/clamping elements during movements of loading/unloading.
This leads to a practice of providing larger spatial separation than actually required thereby inefficient space utilization, which is often observed across the industry & smaller batch quantities result in the uneconomical under-utilization of the process bath capacity.
3.1 Prior art KR102106370B1: The AL anodizing stack structure of reusable spacer with middle bar for work piece.
This invention relates to a stack structure for anodizing aluminum of a reusable spacer with a middle bar for a work-piece to recycle a structure of a spacer form of a plurality of aluminum objects to be plated such as automobile wheels are simultaneously anodized in an electrolytic cell.
According to an embodiment of this invention, the stack structure for anodizing aluminum of a reusable spacer with a middle bar for a work-piece is applied to a stack structure for anodizing aluminum of a reusable spacer with a middle bar for a work-piece to form an aluminum oxide film on the surface of an aluminum object to be plated which is immersed in an electrolytic cell holding an electrolyte.
The stack structure comprises: a middle bar made of a conductive material; anodizing jigs which maintain equal intervals in a longitudinal direction be coupled to the middle bar to be separated, and have a hook on which the object to be plated is detachably mounted; and an elastic member to press the anodizing jigs coupled to the middle bar in an axial direction of the middle bar to prevent the anodizing jigs from being moved from the middle bar during anodizing.
This invention relates to a simultaneous stack structure made of conductive materials to maintain equal interval for anodizing the aluminum work-pieces in longitudinal direction.
This invention in the explained configuration is not applicable for the plurality of longer slender components with the configurations like stiffeners or stringers as the longitudinal & simultaneous loading mechanism of this invention is unsuitable due to the long lengths of the subject components which may result in undesirable contacts/collisions leading to surface defects. To accommodate the long slender components plurality of this invention is required which will increase the weight of the fixture, which is undesirable.
3.2 Prior art UK GB 2089838 Jigs for electrochemical treatment of elongated work-pieces.
This invention is related to an electrolytic treatment of the elongated metal work-pieces as they are supported by a jig, which carries work-pieces in at least two parallel planes electrically connected to a first framework of the jig. Counter-electrodes carried by a second frame which is electrically insulated from the first frame of the jig, form at least one assemblage lying between the work-pieces. The work-pieces and counter-electrodes form a single assembly for lifting into and out of an electrolytic treatment bath.
This prior-art invention is not applicable for the surface conversion process as the complete fixture along with the components together act as a single anode electrode, whereas this prior art invention comprises of at least one assemblage of electrodes lying between said assemblages of work-pieces. Also, this prior-art invention is robust in construction resulting in very heavy structure making it unsuitable for the suspension of the fixture and components system from electrically conducting bar.
3.3 Prior art CN214694428U Anodic oxidation jig
The utility model discloses an anodic oxidation jig, which comprises a connecting rod; the connecting rod is detachably and fixedly connected with a plurality of clamping rings; a plurality of support plates are uniformly arranged on each clamping ring along the circumferential direction, and each support plate is detachably and fixedly connected with the clamping ring; each support plate can be detachably and fixedly connected with a clamping seat, and each clamping seat can be detachably provided with a clamp. The utility model discloses a plurality of snap rings are established on the connecting rod, a plurality of backup plates are established on the snap ring, and the anchor clamps are established on the backup plate, realize surrounding a plurality of anchor clamps that can fix the work piece around a connecting rod, only need put into the anodic oxidation reaction pond with a connecting rod, can carry out anodic oxidation treatment to a plurality of work pieces simultaneously, the oxidation efficiency is high, and the whole volume of tool is less; the detachable fixed connection structure is arranged for connection among the parts, so that the positions and the number of the work-pieces and the clamping positions and modes of the clamps can be adjusted according to actual conditions, the work-pieces with different structural sizes can be conveniently and flexibly fixed, and the fixture is wide in application range.
This prior-art invention is specifically designed for cylindrical, ring-like structures and involves circumferential clamping. This cannot be used effectively for linear components of long length and light weight. Also, it is observed that contact regions of the clamps are relatively more in quantity ensuing in non-anodized zones at clamping areas which would result in local surface defects. These characteristics of the fixture make it undesirable for long metallic components which would need a large & heavy anodizing fixture following the concept of this invention.
4 BRIEF SUMMARY OF PRESENT INVENTION
The objective of this invention is to design a compact light-weight positioning fixture which can load large batch size of plurality of components of same or different configurations in a single charge so that uniform surface characteristics are obtained for the full batch of the charge resulting in improved productivity and quality.
This innovative system is successfully proven for components of different lengths up to 4m and the concept can be extended for longer components as well. This invention resulted in optimal utilization of the facility at full capacity with uncompromising aerospace quality at low cost & minimal maintenance.
5 DETAILED DESCRIPTION OF THE DRAWINGS
This invention can be better understood by reading detailed description of the invention correlating with the detailed description of the drawings in which
FIGURE - 1 Perspective view of the Positioning Fixture
FIGURE - 2: Enlarged ballooned view of the Positioning Fixture
FIGURE - 3: Plurality of components loaded on Positioning Fixture
FIGURE - 4 & 5: Positioning fixture & components immersed in Tank
This invention is designed & constructed using a set of fabricated welded structural frame made of plates [5] which acts as a support module, a set of staggered strap claw clamp pairs [6, 7 & 8, 9] for holding the parts at defined holding stations, twisted hanging hooks [1] so that the connection and disconnection to rectangular bar is easy and can be done smoothly and also to provide structurally stable connection, the bar is an electric conducting bar [B] for the process of surface conversion. The design also consists of fastening elements like tightening bolts, nuts and lock pins [2, 3, 4].
[B]- The bar is an important part of the setup of an electrochemical process of surface treatment, its main function is to conduct electricity to the work piece via an electrically conducting suspension media so that the electrolysis reaction can take place on the work-piece.
[1]-This hanging hook is a metallic twisted hook which is used to hang the fixture structure. This design ensures sufficient contact surface for conduction of electricity and sufficient strength for the load bearing of suspending members.
[2]- Tightening bolts will be used to fasten the hook against the conducting bar [B], this will ensure firm positioning of the fixture structure at desired location and restricts the unnecessary swinging movements of the fixture structures to avoid contacts/collisions between the parts/fixture elements which will result in surface defects due to contact burns.
[3]- The tightening lock nuts are specifically used to lock the structure using its self-locking mechanism, it is designed to resist loosening under any loads this structure might experience during transits & operation.
[4]- Lock pins are used to secure the connection between the hook [1] & the structural members [5], to avoid any oscillatory/swinging movements.
[5]- It is a structural support frame, consisting of 4 plates welded together making a rectangular support structure.
[6]- Short Claw (bottom) is designed to take the most of the load of the component with minimal contact.
[7]- Short Claw (top) is placed right above the botom claw to hold the component firmly in position with minimal contact.
[8]- Long Claw (bottom) has the same function as [6], but there is a difference in length which will enable staggered yet firm positioning of components. This also helps in effective space utilisation and the risk of undesired contacts between the components is also eliminated by virtue of this design.
[9]- Long Claw (top) has the same function as that of the short claw (top) [7] but designed with a matching length as that of Long Claw (bottom).
[E]- Electrolytic solution which is the electricity conducting media
[W]- Workpieces with different representative configurations, but not limited to, having lengths varying between 500mm & 4000mm
[T]- Surface Conversion process bath tank assembly
[A]- Set of all fixture elements [1] to [9], conducting bar [B], along with components [W] together act as Anode
6 DETAILED DESCRIPTION OF INVENTION
“Positioning Fixture for a Surface Conversion Process of Metallic Components” is an inventive solution for loading, surface conversion & unloading the charge, employed for in particularly, but not limited to, long thin sheet metal components of different lengths & widths.
The fixture system is made up of metallic structural elements & fasteners. The material used for the construction of the fixture is selected to have relatively significantly lesser electrical conductivity and higher non-reactivity than that of the components to ensure minimal effect of the electro-chemical reaction of the process on the fixture system. This property also results in slower electro-chemical process with better process control & non-contamination of the process bath due to the selected fixture material.
Main support structure is a set of fabricated welded structural frame made of 4 pieces of plates [5]. The design also includes bottom claw clamps [6 & 8] which act as component’s weight bearing members. Top Claw Clamps [7 & 9] are designed to firmly hold the components in pre-determined spatial position. Limited inherent flexibility achieved by the design of the claw clamps helps in forced opening of the clamp mouth for loading & unloading the components easily without causing any damages. The clamps hold the components firmly & safely throughout the process with minimal surface contact. For additional reinforcement, bottom clamps [6 & 8] can be supported by suitable gussets on need-basis. Additionally, the claw clamps have two different selected lengths, short claws [6 & 7] & long claws [8 & 9]. The sets of short & long claws are alternatively arranged to obtain staggered positioning of the components which allows loading the components safely at relatively shorter distances by means of loading on different lateral planes.
Twisted hanging hooks [1] are connected to the frame by means of lock pins [4] and also welded to the frame for rigid joint. Hooks are useful in getting easily connected or disconnected to rectangular bar which is an electric conducting bar [B] for the process of surface conversion. Tightening Bolts [2] & Tightening Lock Nuts [3] are used to position the support frames firmly at a desired position as required based upon the lengths of the components.
For longer components, it is required to have at least two clamping zones along the length. This is achieved by introducing one more set of support frame with claw clamps & twisted hook arrangement at geometrical linear orientation at a set distance which can be adjusted by means of changing the location of the hanging hooks [1] to accommodate the components of different lengths.
Additional set of the claw clamp arrangement is mounted on the back sides of the both frames effectively resulting in front side & back side loading of the components which helps in counter-balancing resulting in better stability apart from bigger batch size for loading. This results in loading of large number of similar components in a single process cycle to obtain comparable surface characteristics on in a single batch of loaded components.
Above arrangement results in horizontal loading of components which is preferred over vertical loading because it prevents a single clamp to undergo the entire load thus, decreasing the chances of failure. Also, it ensures uniform temperature zone across the entire length of the component.
The range of lengths for which this positioning system is designed for efficient use is defined to be up to four meters.
The said positioning fixture is assembled such that, the fixture, conducting bar, and the work piece, all act as anode [A], while the process bath tank acts as the cathode [C]. All the components acting as anode [A] are immersed into the electrolyte of electro-chemical process bath without disturbing their relative positions.
This system results in conjoint staggered arrangement of aerospace components to completely avoid any unwanted loose contacts among themselves as well as with tooling items. At the same time, the system maintains necessary firm & safe spatial separation due to the design & positioning of holding stations. This system also results in undamaging, essential & minimal contact resulting in no contact burns.
By means of all of the above features, the system provides the necessary uniform surface conversion to obtain uncompromised aerospace quality even when running at full capacity of the system. Material selected for the construction is non-reactive to the electrolyte, because of which this system can be used for a significantly large number of loading cycles (around 1,000 cycles) with nominal to no requirements of maintenance and also without contamination of process bath solution.
Current innovation resulted in optimal utilization of the facility at full capacity, covering a wide range of components of different lengths. Multiple numbers (up to 60 no’s) of components of similar configurations can be loaded for a single process cycle resulting in comparable surface properties in the full batch.
This re-usable system uses the space efficiently, with which different configurations of components can be processed in a single load. This system is user-friendly and at the same time no rejections or reworks were found, thereby productivity is increased by almost THREE times, which resulted in significant energy savings & cost savings in process operations as well as maintenance.
This invention is particularly in use, but not limited to the said surface conversion application for loading plurality of components of different configurations in multiplicity of parallel planes in longitudinal & staggered lateral planes in an optimized manner providing firm & safe spatial separation of components apart from minimal surface contact, resulting in very high productivity, efficient process tank capacity utilization and uniform aerospace class quality. This invention can be adapted to suit other similar applications. , C , C , Claims:We claim,
1. A method involving the surface conversion process of a plurality of slender metallic components, positioned in multiplicity of parallel longitudinal and lateral planes and a positional fixture comprising:
a conjoint and electrically conductive fixture further comprising:
a set of metallic structural elements like the structural members [1 to 9], conducting bar [B], and the work pieces [W];
a electro-chemical surface conversion process bath tank [T] consisting of electrolyte solution [E] as conducting media;
wherein the said conductive positioning fixture [1 to 9], along with the components [W] and conducting bar [B] together act as anode [A] and said process bath tank act as cathode [C]; and
said set of anodic elements [A] are immersed into said electro-chemical process bath tank [T] ensuring firm and safe spatial separation.
2. According to the claim 1, the hanging hooks [1] in the said positioning fixture can be adjusted to clamp components of different lengths.
3. According to claim 1 & 2, the holding stations of the said positioning fixture are arranged in a manner such that one holding station is placed vertically over the other.
4. As per claim 1 to 3, longitudinal axes of the said components are placed in parallel horizontal planes with a provision of positioning alternative, staggered lateral vertical planes.
5. The positioning fixture system given in claim 1 to 5 consists of a main structural support frame [5] made of four plates welded together, a set of twisted hanging hooks [1] are connected to the said support frame [5] through a pair of lock pins [4] generating a structurally stable connection between the two. Other end of the said hook is hung on an electrically conductive bar [B] by the means of tightening bolts [2] and nuts [3] to facilitate the surface conversion process of the components [W] with firm and safe spatial separation inside the electrolytic solution [E] of the surface conversion process tank [T].
6. The positioning fixture of claim 1 comprises of two sets of claw clamps [6 & 7; 8 & 9] of different pre-defined lengths, which are arranged in alternate manner for lateral separation of the loaded components in a staggered way, using the space efficiently.
7. The fixture according to claims 6 and 7 comprises of sets of claw clamps placed on top [7 & 9] and bottom [6 & 8] which are used to hold the components firmly by keeping it steady and to take the entire weight of the component respectively.
8. As per claim 1 to 5, the fixture is possessing component holding stations on frontal and rear direction of the said structural support frame [5].