Hydro ironing

Abstract

In the proposed hydro ironing method, through an innovative arrangement of loads and using a novel configuration for the die components, the thickness reduction in one stage of ironing is almost equal to twice the common approaches.

Claims

1. A 3d Hydro ironing tool comprising: An upper shoe, a middle shoe and a lower shoe, a die stem, wherein said tool is attached to said upper shoe via a place holder for said die stem; furthermore a mandrel is fixed to said upper shoe via a mandrel holder; a position of said upper, middle and lower shoes is adjusted and defined via two guide posts (preferably cylindrical posts) that are located in and fixed to said lower shoe by two post holders and screws or any connecting means capable of fixedly and tightly holding and securing said two posts to said lower shoe and keep them in place; wherein said two post holders are connected to said lower show and said two posts pass through and along a length of said two post holders; wherein said two posts are located parallel to and on either side of said mandrel keeping said upper, lower and middle shoes parallel to each other; wherein said mandrel moves up and down and is guided and adjusted in place, by two linear ball bearings located around said two posts and fixed in position by their respective housings in said upper shoe; wherein said housings are fixedly attached to said upper shoe and face said central shoe; said tool further comprises a die reinforce set attached and fixedly connected to said middle shoe having comprises two pins press fitted in prepared places in order to accurately guide a cup holder, wherein a hydro ironing die is also press fitted inside said die reinforce set on said middle shoe, and wherein an ironing ring is also press fitted in said mandrel, reducing elastic deformation through a hydro ironing process; said tool further comprises: a pump unit, first and second switches; wherein said pump unit controls flow of oil inside said drawn cup as well as a predetermined first and second pressures forces on an inside and outside surface of said drawn cup, and wherein said first and second switches open and close an inlet and outlet for said pump unit adjusting said first and second predetermined pressures as needed.

2. A 3D hydro ironing process comprising the steps of: placing a deep drawn cup in a die; wherein an ironing ring is placed and set on an edge of said drawn cup, where said cup edge is held by a holder; then a loader (attached to a jack rod) applies an axial constant preset force on a bottom of said drawn cup while a hydrostatic oil is pressure is applied to an inner surface of said drawn cup; then said ironing process starts from said cup edge; at this step said oil is forced into and inside said drawn cup via a central inlet through a mandrel therefore eliminating a need for sealing of said oil and having a containing chamber; at this point a pressure inside said drawn cup reaches to a first predetermined pressure wherein said pressure at a ring-cup interface prevents said oil from leakage; then said ring establishes a pressing contact from said cup edge into said inner surface of said drawn cup and moves downwards towards said bottom of said drawn cup and touches said bottom, meanwhile said loader applies a constant force which is defined by a second predetermined pressure on an outside surface of said drawn cup keeping it in place; at this step said ring is unloaded and comes out of said drawn cup while said first predetermined pressure is still present inside said drawn cup; then said loader returns back to its original place and therefore expels a drastically thin-walled formed specimen.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1, displays a schematic illustration of main parts and applied forces.

(2) FIG. 2, displays an isometric view of designed hydro ironing tooling.

(3) FIG. 3, displays cross section views of designed hydro ironing tooling.

(4) FIG. 4, displays detailed view (C) of main forming parts.

(5) FIG. 5, displays hydraulic circuit used in hydro ironing process.

(6) FIG. 6, displays schematic deformation of products through deep drawing and hydro ironing processes.

(7) FIG. 7, displays typical indents formed on a thin-walled product.

(8) FIG. 8, displays typical indents formed on a thin-walled product.

DETAILED DESCRIPTION OF SPECIFICATION

(9) Designed Tooling and Test Procedure:

(10) A schematic illustration of main parts and applied forces are shown in FIG. 1. At the beginning of the process, a deep drawn cup 19 is put into the die 17 and the ironing ring 7 is set on the cup edge 38 while the cup edge is held by holder 8. At the same time a part named Loader 16 which is set on jack rod 11 applies an axial force to the cup bottom while a hydrostatic oil pressure is applied to the inner surface of the drawn cup. The ironing process begins from the edge of the cup. This tool configuration makes it easy to apply hydro static oil pressure (P, FIG. 1) to the inner surface of the cup, eliminating the need for sealing of oil and the need for a containing chamber.

(11) The ring 7 comes down and establishes a pressing contact with the cup wall (FIG. 1, left). Then the cup is filled with the oil coming from the central hole 24 of the mandrel 6 and its pressure reaches to a pressure which is preset on R.sub.1 (FIG. 5). The pressure at ring-cup interface prevents the oil leakage. Afterward, the ring 7 comes down (FIG. 1, right) until it touches the cup bottom.

(12) Meanwhile, Loader 6 applies a constant force, which is defined by preset pressure on R.sub.2 (FIG. 5). After the ironing stage, the ring comes out of the cup while the cup edge is unloaded and there is still a low pressure (set by R.sub.1) in the cup. Then, loader comes back to its former place, expels the formed specimen and would be ready for putting the next specimen.

(13) Although using a double action press would ease the process and lower the number of tooling components, the hydro ironing tooling (FIG. 2) was designed so that it could be used in an ordinary workshop with a simple single action press. As shown in FIG. 3, the tooling is connected through prepared place for the die stem 1 in the upper shoe 2. The mandrel is fixed on the upper shoe by mandrel holder 15.

(14) This shoe is guided by two linear ball bearings 3 which are fixed in position by two housings 4 on the upper shoe. The hydro ironing die 17 is press fitted in a part named Die Reinforce 18 and so was the ironing ring 7 on the mandrel 6, to reduce elastic deformation through the Hydro ironing process. The ironing die and Die Reinforce were set on the middle shoe 9.

(15) The position of lower 14, middle and upper shoes are specified using two guide posts 5 which are positioned in the lower shoe by two guide post holders 13 and are fixed by two Allen screws placed in 14. Almost all cylindrical parts (like 5, 7 and 17) are positioned in their places using their cylindrical feature and non cylindrical parts (like 4, 13, 15 and 18) are fixed in shoes using four screws (like 32 for 4) and positioned by two pins (like 33 for 4 or 22 for 18).

(16) A pipe 10 was used to prepare needed space between middle and lower plates to place hydraulic jack there. Some parts of it, 24 and 25, where removed as a path for outlet 27 and inlet 26 of the jack cylinder 12. The pipe between lower and middle plates is fixed using two partially threaded rods 30 and four screws 31.

(17) As shown in FIG. 4, the punch is fixed through a circular plate 35 and four conic Allen screws 34 on the mandrel. The conic part of common ironing rings is considered as a combination of an arc (corresponding to the cup final bottom curvature, 37) and a conic part 36.

(18) Also, a projection like a draw bead 40 was used on ironing die for better clamping of deep drawn cup edge 38. In order to precisely put the cup holder on the cup edge, two pins 20 are press fitted in prepared places 21 on the Die Reinforce which will accurately guide the cup holder.

(19) A pump unit was used in hydro ironing process to supply needed pressures as is shown in FIG. 5. The cup, and ring together with mandrel are shown as a C.sub.1 cylinder which is set on the hydraulic jack C.sub.2. The oil flow to C.sub.1 and C.sub.2 would be controlled by S.sub.1 and S.sub.2, respectively. Also, the pressure of both C.sub.1 and C.sub.2 can be monitored and adjusted independently by G.sub.1 and G.sub.2, and R.sub.1 and R.sub.2, respectively.

(20) Using an automatically controlled hydraulic circuit would drastically enhance speed of the process. Also, if the gap between cup holder 8 an mandrel 6 is sealed at the beginning of the process (FIG. 1), the initial specimen can be a plane blank 41 which is first deep drawn 42 (sheet hydro forming) and then hydro ironed 44 consequently in the same die (FIG. 6).

(21) Furthermore, as there is outflow during the forming step, low flow components can be chosen for the hydraulic circuit which is important from the initial-tooling-cost point of view.

(22) Products:

(23) This process is capable of producing thin-walled components, with a drastic reduction in thickness in one stage of hydro ironing. The isometric view of initial blank 41, deep drawn cup 42, deep drawn cup during hydro ironing process 43 and hydro ironed specimen 44, and their cross section (45, 46, 47, and 48, respectively) are shown in FIG. 6.

(24) This drastic reduction in thickness (the wall thickness of 46 in comparison with 48) results in a great increase in height of products and a significant improvement in their mechanical properties like tensile strength and hardness. High dimensional accuracy and surface roughness of products are other advantages which are of the nature of ironing process as a cold forming process.

(25) The capability of producing thin-walled products with convexities on their outer surfaces is another application of this process. Typical indents 49 which are produced on a thin-walled cup 50, its upper view 51 and cross section views with 52 and without 53 indents (cross sections D-D and E-E, respectively) are shown in FIG. 7. Also, a typical rib 54 which is produced on the cup 55, its upper view 56 and cross section F-F 57 is shown in FIG. 8.

(26) These features may act as any type of indents on hollow cylindrical products (like that of drum clutches of automobiles) or a replacement of curled, bulged or threaded parts of them. These applications will reduce the stages of manufacturing a product and also may provide the possibility of producing features which were hard or impossible to produce in conventional methods.

(27) In the end this process will: 1. Increases the reduction in area by two folds and even more as compared to the conventional process. 2. Prepares the capability of using materials with low workability characteristics based on the compressive nature of the proposed method. 3. Uses fewer tooling and operations which results in reducing the manufacturing time and expenses. 4. Reduces the energy consumption and pollution 5. Reaches products with better mechanical properties like higher hardness and tensile strength due to severe plastic deformation (SPD) of workpiece. 6. Prepares the capability of adding some features like ribs, indents etc., which from assembling point of view could reduce the manufacturing cost and time.

(28) It is understood that the above description and drawings are illustrative of the present invention and that changes may be made in materials, design and method steps without departing from the scope of the present invention as defined in the following claims.