DESC:FIELD OF THE INVENTION

This invention is related to a cylinder head assembly automation system.

SCOPE AND APPLICABILITY OF INVENTION

This invention is particularly related to a cylinder head assembly automation system for an IC engine.

BACKGROUD OF INVENTION

A cylinder head assembly is crucial for proper functioning of engine and requires accuracy while assembling various components on cylinder Head. Cylinder Head assembly has very minute and precise tolerated parts. It comprises the Exhaust and Inlet Valve assemblies, which have extremely high contribution towards the fuel efficiency, power and performance of the vehicle. Inlet and Exhaust valve assemblies comprises of very small and precise parts like inlet and exhaust valves, valve springs, seat, retainer, stem oil seal and cotter valves also called as collets. These parts need to be assembled through a series of operation. A typical 4 Valve cylinder head assembly has 7 different parts each & a total part count of 28 numbers in the valve assembly. Same is shown pictorially in figure 1.

PRIOR ARTS

Normally this assembly of cylinder head is done manually. The manual method of cylinder head assembly has many disadvantages. Highly skilled manpower required for manual method. For example a 4 valve cylinder head assembly operation may require 4 men in one shift for producing 1200 nos. of cylinder head assemblies. The manual method is low productive because of complicated assembly of collets, leading to repeated attempts to get collets locking correctly. For example a first time correct production of cylinder head assembly may not exceed 90%. Further there is time lost during model changeover in manual method due to change in position, parts etc. For example average 5 minutes per model change, leading to an average loss of 50 minutes per day for 10 models. Time is also lost because of non-availability of correct parts at the assembly stage. There are quality issues leading to high rework/ rejection. The main quality issues are seat missing in the sub assembly, double seat assembled, spring assembled reverse direction (Wrong orientation), collets assembly failure, part mix up (Different model part assembled), valve greasing not done and valve seat cleaning not done etc.

The applicant has invented an automation system for cylinder Head assembly to overcome the drawbacks of prior art.

OBJECTIVES OF THE INVENTION

An objective of the invention is to provide a cylinder head assembly automation system which reduces quality issues, rework and rejection.

Another objective of the invention is to provide a cylinder head assembly automation system that doesn’t required skilled manpower.

Another objective of the invention is to provide a cylinder head assembly automation system that requires less manpower.

Another objective of the invention is to provide a cylinder head assembly automation system which has high productivity.

Another objective of the invention is to provide a cylinder head assembly automation system which has substantially less time loss during model changeover.

Another objective of the invention is to provide a cylinder head assembly automation system which has a minimum time loss due to non-availability of right parts at the assembly stage.

Another objective of the invention is to provide a cylinder head assembly automation system which requires substantially less and compact space.

SUMMARY OF THE INVENTION

As per one of the embodiment of the invention, the cylinder head assembly automation system comprising plurality of stages for picking up of items, sub assembly and final assembly wherein the said stages are provided with vision systems, robotic devices with a pre-programmed sequence of operation/ movement; the said vision system capable of capturing the images of assembly parts and provide this input to said robotic devices to perform programmed/ desired activity.

The cylinder head assembly automation system comprising automatic work changer which consists of a atleast one fixtures for mounting atleast one cylinder head wherein the said fixture/s provided with plurality of servo motors for performing linear and rotary movement of fixture/s.

Preferably these fixtures are mounted of indexer; the said indexer is provided with a motor to index/ rotate the fixtures in various desired positions.

The cylinder head assembly automation comprising servo stacker module which consists of plurality of servo feeders and pallets wherein atleast one pallet is moved in vertical direction and atleast one pallet is moved in horizontal direction by servo feeders.
The cylinder head assembly automation system comprising a vision system which captures image of components stored in the pallets; the said vision system analyzes the image for predefined dimensions and orientation of components for selecting correct component and further identify the position of correct component in the pallet and communicate this position to robot for pickup.

The cylinder head assembly automation system comprising a robot which has at least one gripper which, acting on the feedback from the vision system, picks up the correct component from the pallet and moves it to desired position.

The cylinder head assembly automation system comprising feeder system; the said feeder system comprises a storage tray and atleast one vibratory tray to store and feed the components to robot.

Preferably the storage tray of the feeder system is a vibratory tray to feed the components to another tray by vibration.

Preferably, vibratory tray of feeder system has linear grooves in which the components are aligned in a particular direction for example the direction of grooves when the tray is vibrated.

The feeder of the cylinder head assembly automation system comprising atleast one collection box where remaining components in the vibratory tray, due to not picked by the robot after identified as wrong model or wrong orientation or wrong size, are collected.

The cylinder head assembly automation system comprising a robot which has plurality of grippers to hold and pick the parts wherein atleast one gripper has provided a hollow slot on one of its side surface to facilitate operation of another gripper through the said slot.

The cylinder head assembly automation system comprising atleast one conveyer which moves the pallets containing components and sub-assembly of components to desire positions; the said sub-assembly contains seat, spring, retainer and collets.

The cylinder head assembly automation system comprising a vision system which captures image of sub-assemblies stored on the pallets of conveyer; the said vision system analyzes the image to identify the correct assembly of sub-assembly on the pallet and communicate to robot for pickup.

The cylinder head assembly automation system comprising atleast one servo pressing tool which performs the assembly operation of Valves and the pre-assembled sub-assembly in the cylinder head by pressing the springs to a pre-defined length so that collet locking groove on valve stem and the collet locking projection on collets are placed opposite to each other.

Preferably, the servo pressing tool comprising a at least one ball point centre plunger which locates & holds the collet halves in the retainer securely during (a) pickup of the sub assembly from pallet, (b) during movement of sub-assembly from pallet to cylinder head, (c) during placing of the sub-assembly on cylinder head and (d)during pressing operation.

Preferably, the servo pressing tool comprising at least one collet pusher plunger which supports the collets from top during assembly operation.

Preferably, the servo pressing tool comprising a retainer guide provided with a taper profile at its outer periphery at its lower end; the said taper surface corresponding to taper profile of top surface of retainer for centralizing the retainer during assembly operation.

Preferably, the servo pressing tool comprising an orientation mechanism which consists of atleast one motor and gear to rotates the press tool along with gripper around axis of the pressing tool in desired position, so as to avoid fouling of the gripper with the projected portion of cylinder head and its holding fixture during assembly operation.

As per one of the embodiment of invention, the cylinder head assembly automation system as claimed in any above claims is arranged in a compact layout wherein automatic work changer is placed at one end of the layout. The servo stacker module is placed at another end opposite to the automatic work changer. Feeders are placed at another end of the layout adjacent to servo stacker module. The conveyer is placed at another end of the layout adjacent to automatic work changer .One Robot is placed between automatic work change and servo valve stacker. Other robots are placed between feeders and conveyer. Vision systems are place above the servo stacker module, vibratory trays and conveyer in the layout.

Preferably, the layout of cylinder head assembly automation system may be of any shape for example rectangular shape in the one of the embodiment of the present invention. The various modules are located at any place in the layout such as corners, sides etc. All permeation combination of the placement of module in the layout are within the scope of this invention.

Preferably, in the layout of the cylinder head assembly automation system, a robot is placed between feeder and pallet so that the movement of gripper of robot from feeder to pallet is least.
Preferably, in the layout of the cylinder head assembly automation system, plurality of feeders and valve stacker are placed at same side of layout adjacent to each other so that the refilling of components in feeders and stacker can be done easily by a single operator with very less movement.

Preferably, in the layout of the cylinder head assembly automation system, the conveyer is of close loop type so that the pallets of the conveyer on which the components and sub-assemblies are mounted are guided on the conveyer to desire positions and when these components are picked up by the robot, the empty pallets are guided for next position.

Preferably, in the layout of the cylinder head assembly automation system, plurality of control panels are placed at outer side of layout so that the maintenance of control panels can be done easily by an operator from outside of the layout. This also makes working area of layout compact.

A method of cylinder head assembly comprising steps of
a. Loading a cylinder head on automatic work changer.
b. Feeding the valves from stacker module to robot by moving the trays in horizontal and vertical direction by servo motors.
c. Identifying the correct valve and its position in the trays by vision system and communicating this to robot for picking up the valve.
d. Picking up the correct valve by robot and placing it on the cylinder head valve guide.
e. Feeding the sub-assembly components from respective storage trays to respective vibratory trays by vibration. or gravity.
f. Identifying the correct sub-assembly components and its position in the trays by vision system and communication this to respective robot for picking up the correct sub-assembly components.
g. Picking up the correct sub-assembly components by receptive robot and placing it on a locator provided on pallet of conveyer to make sub-assembly of these components.
h. Moving the pallet by conveyer near the servo press tool.
i. Checking the correct sub-assembly of components by vision system and communicating it to servo press.
j. Picking up of correct sub-assembly by servo press tool and placing it on cylinder head valve stem.
k. Pressing of sub-assembly on cylinder head by servo press tool.

A method of cylinder head assembly by servo press tool comprising steps of
a. Initial pressing of sub- assenbled componemts by servo press tool to creates a radial gap between outer faces of collets and taper surface of retainer guide allowing the collets halves to move sidewise in the gap and thus creating space for valve stem to enter between collet halves.
b. Further pressing by servo press tool to predefined stroke making entry of valve stem inside collet halves to bring collet locking groove on valve stem and the collet locking projection on collets opposite to each other.
c. Reverse movement of press tool allows locking of projection of collets in the groove of valve stem due to force exerted on collet halves by the taper face of retainer, thus completing the cylinder head assembly.

DETAILED DESCRIPTION OF FIGURES

Numeral Description
1 Cylinder Head
2 Intake Valve
3 Exhaust valve
4 Stem oil seal
5 Seat
6 Spring
7 Retainer
8 Collet
10 Cylinder Head Assembly
11 & 12 Cylinder Head mounting fixtures
13 & 14 Cylinder heads
15 & 16 Servo motors
17 Indexer
20 Automatic Work Changer (AWC)
21 Pallets
22a, 22b, 22c, 22d Vision systems
23 & 24 feeders
25 Valve outer diameter
26 Valve inner merging diameter
27 identification letter
28 Valve face
30 Servo Valve Stacker module
31 Robot 1
32 & 33 Arms of robot 1
34 Pusher cylinder
35 & 36 valve guides
41 Robot 2
42 & 43 Feeders
44 & 45 Grippers
46 Locator
47 Pallet
51 Robot 3
52 & 53 Grippers
55 Conveyer
56 & 57 Feeders
58 Valve axis
61 Servo system
62 & 63 Servo presses
64 Indexer
65 Pick up gripper
66 Pressing tool
67 Ball point Plunger
68 Retainer guide
69 Pressing axis
70 Inner Taper face of retainer guide
71 Special Taper profile
72 Valve top face
73 Collet bottom face
75 Groove
76 collet pushing plunger
77 Valve stem
78 collet locking projection
79 Radial gap
80 Rectangular space
81, 83, 85, 87 4 corners of rectangle
82, 86 Small sides of rectangle
84, 88 Big sides of rectangle
89 Pre-assembly of Seat, Spring, Retainer & collets
90 Orientation Mechanism
91 Storage tray of Spring feeder
91a Vibratory tray of Spring feeder
91b Grooves or slots
92 Storage tray of Seat feeder
92a Vibratory tray of Seat feeder
93, 93a Storage & Vibratory tray of Collet feeder
94, 94a Storage & Vibratory tray of Retainer feeder
95, 96 Collection boxes
97 Slot
98 Indexer
99 Gear
100 Gear
101 Vision system checking seat and spring orientation
102 Vision system for checking sub-assembly of sear, spring, retainer & collets
103 Control panels
104 Main PLC panel

Figure 1 is pictorial view of a typical 4 valve cylinder head assembly of IC engine.

Figure 2a and 2b are side and top view of Automatic Work Changer (AWC) according to the preferred embodiment of the invention.

Figure 3a, 3b and 3c are front, top and side views of Servo Valve Stacker according to the preferred embodiment of the invention.

Figure 3d is an isometric view of a typical valve according to the preferred embodiment of the invention.

Figure 4a, 4b, 4c and 4d are views explaining the working of robot I according to the preferred embodiment of the invention.

Figure 5a, 5b, 5c, 5d, 5e and 5f are views explaining the working of robot II according to the preferred embodiment of the invention. Figures 5e’ and 5f’ are enlarged view of figures 5e and 5f respectively.

Figure 6a, 6b, and 6d are views explaining the working of robot III according to the preferred embodiment of the invention. Figures 6c and 6e are expanded views of marked parts of figures 6b and 6d respectively. Figure 6c’ and 6f are side views of figure 6c and 6e respectively.

Figures 7a & 7b are isometric view & front view of conveyer pallet according to the preferred embodiment of the invention.

Figure 8 is an isometric view of servo system according to the preferred embodiment of the invention.

Figure 8a and 8c are views explaining the working of servo system for transferring pre-assembled parts to pressing tool according to the preferred embodiment of the invention. Figures 8b and 8d are expanded views of marked parts of figures 8a and 8c respectively. Figure 8e is view explaining orientation mechanism.

Figure 9 is an enlarged view showing various parts of pressing tool and cylinder head assembly according to the preferred embodiment of the invention.

Figure 9a to 9g are views explaining the sequential working of pressing tool for collets assembly according to the preferred embodiment of the invention. Figures 9a’, 9c’, 9e’and 9f’ are expanded views of marked parts of figures 9a, 9c, 9e and 9f respectively.

Figure 10 is a top view explaining the compact layout of the cylinder head assembly automation system according to the preferred embodiment of the invention.

A typical 4 Valve cylinder head assembly 10 comprises a cylinder head 1, two inlet valves 2 and two exhaust valves 3. Each valve is assembled with 7 different parts namely Stem oil seal 4, seat 5, valve spring 6, retainer 7 and two collets 8. . Same is shown pictorially in figure 1.

According to one of the preferred embodiment, the cylinder head assembly automation system comprising 7 stages as follows and described with the help of figures 2 to 10.

Stage1: Automatic Work Changer (AWC) (20):

Referring to the figures 2a & 2b, this AWC consists of a twin fixture 11 & 12 for mounting two cylinder heads 13 & 14 respectively. Each fixture consists of two servo motors 15 and 16. One servo motor 15 is for correction in axis Z (Linear movement of complete cylinder head to match insertion point of valve axis), and another servo motor 16 is for rotation of fixture ( to align valve axis 58 with press tool axis 69 which is always vertical). These are required to accommodate any model of cylinder head, to adjust the system to the variations in designed Valve angles. The fixtures are mounted on 180 degree indexer 17 which reduces the load/unload time of cylinder head. When operator unloads assembled cylinder head 13 & loads new cylinder head (not shown) on fixture 11 for assembly, the other cylinder head 14 on 2nd fixture 12 is being assembled at other side by robot.

An auto cleaning facility (not shown) may be provided on AWC. When the cylinder head is loaded on fixture, an automatic ionized air blast is blown for 10 seconds towards fixture, which cleans the valve seats & valve guides on cylinder head. Ionized blaster neutralizes static electricity and removes dust.

Stage 2: Servo Valve Stacker Module(30):

Referring to the figures 3a, 3b, 3c & 3d, this module has an array of pallets 21 (for example ten pallets for the present embodiment) to store the Inlet valves 2 and exhaust valves 3 of various models. The data of model name to each pallet is stored in the system. Each pallet 21 stores number of valves of one model, for example sixty four Valves in the present embodiment. Stacker module has programmed intelligence to offer the correct model of valves to the system. The pallet 21 containing the correct model of valves is moved vertically by means of a linear servo (vertical) feeder 23 and positioned at the output area by means of a pneumatic (horizontal) feeder 24. It also has two vision systems 22 which cross checks the valve being assembled is as per the required model or not. Vision system 22 captures image of pallet where valves are stored. This vision system further analyze this image and measures the dimensions of valves such as outer diameter 25, inner merging diameter 26 & identification marks 27 punched on the valve face 28 and compares it with already saved dimensions of valves of various models to identify correct valve. The vision system 22 further communicates the position of correct valve on pallet to robot I for picking up.

Stage 3: Robot I (31) for assembling Valves:

Referring to the figures 4a, 4b, 4c & 4d, this is a multi axis Robot I (31) (for example 6 axis in this embodiment), which picks up the inlet valves 2 and exhaust valves 3 from the Servo Valve stacker pallet 21 with its arms 32 & 33 respectively according to feedback received from vision system 22 and moves it to auto greasing unit (not shown), where the grease is applied to valves (2,3) and then inserts the valve (2 or 3) in the cylinder heads 1 in respective valve guide (35 or 36) which is mounted on AWC (as indicated in earlier paragraph of stage 1) and hold the valves 2 or 3 in their desired position by pusher cylinder 34. This pusher cylinder 34 may be an integral part of robot I (31). Very minimal time is required for valve insertion. (For example 7 seconds in this embodiment). The same procedure of valve insertion is repeated for remaining valve after completing the first valve assembly.

Stage 4: Robot II (41) & feeders for sub-assembly of Spring-Seat and Springs:

Referring to the figures 5a, 5b, 5c, 5d, 5e & 5f, there are feeder 42 for springs 6 and another feeder 43 for seats 5. Feeders 42 and 43 has storage trays 91 and 92 respectively where components are stored. Components (springs 6 and seats 5) are kept in respective trays (91, 92) from where controlled number of components is fed into vibratory trays (91a, 92a) by vibration or gravity. Vibratory tray 91a has grooves or slots 91b in which the springs 6 are aligned in the direction of grooves 91b when vibrated. The components are vibrated here for a fixed time for few seconds, after which Vision system 22 captures the image of this tray (91a, 92a) where components are stored. This vision system 22 further analyze this image and measures the dimensions of components such as size, orientation and compares it with already saved dimensions of components of various models to identify correct component and further communicates the position of these components on the vibratory tray (91a, 92a) to the Robot II (41) for picking up. Some components may remain in the vibratory trays 91a and 92a and are not picked by the robot due to reasons that they may be identified as wrong model or wrong orientation or wrong size etc. These components are collected in the collection box 95 and 96 below the vibratory trays 91a and 92a for further disposal.

Robot II (41) has pluralities of gripper (For example two grippers 44 for picking springs 6 and two grippers 45 for picking seats 5 in this embodiment). Robot II (41), acting on the feedback from Vision system 22a & 22b , moves in and picks up the springs 6 and seats 5 using respective grippers (44 & 45). It assembles the seat 5 and spring 6 sequentially on locator 46 of the pallet 47. Pluralities of locator 46 are available on the pallet 47 to assemble pluralities of springs & seats. (For example two locators 46 in this embodiment). Vision system 101 checks the spring 6 & seat 5 for correct orientation. Once the vision system 101 confirms the assembly is done correctly, the pallet 47 indexes forward to next position for Robot III (51). Each pallet 47 has assembly of plurality numbers of assemblies of seat 5 and spring 6, (For example 2 assemblies in this embodiment). This assembly is completed in a very less time. (For example cycle time of less than 12 seconds in this embodiment).

Stage 5: Robot III (51) & feeders for assembly of Retainer and Collet:

Referring to the figures 6a, 6b, 6c, 6c’, 6d, 6e, 6f, 7a, 7b & 10, there are another 2 feeders (56 & 57) in this stage, one feeder 56 for retainers 7 and another feeder 57 for collets 8 respectively. Functioning of these feeders is same as described for Robot II feeders. In this stage also there are 2 vision systems (22c, 22d) for identifying the correct components and position of component in the tray (93a, 94a).

Robot III (51) has pluralities of gripper (For example two grippers 52 for picking retainers 7 and four grippers 53 for picking collets 8 in this embodiment). Robot III (51), acting on the feedback from Vision systems 22c, 22d, moves in and picks up the retainer 7 and collets 8 using respective grippers (52 & 53). Gripper 52 has a hollow vertical slot 97. Gripper 53 is a vacuum type gripper. Gripper 53 picks two collets 8 by vacuum cup. It rotates by 90 degrees and enters through the hollow slots 97 of gripper 52 from both sides to keeps two collets 8 on retainer 7 simultaneously in correct position. Gripper 52 keeps this assembly of one retainer 7 and two collets 8 on the already assembled seat 5 and spring 6 on each locator 46 of pallet 47. (For example two assemblies in this embodiment). This is completed in a very less cycle time. (For example cycle time of less than 12 seconds in this embodiment).

Stage 6: Conveyor (55) with pallets (47):

Referring to the figures 7a, 7b & 10, there is belt driven close loop conveyor 55 of rectangular shape having plurality of pallets 47 (for example 16 in this embodiment) on which Seat 5, spring 6, retainer 7 and collets 8 are pre-assembled on each locator 46 of pallets 47. The conveyor 55 positions the pallets 47 precisely in front of Robot 2, Robot3 and Servo system for assembly / pick up operations by means of stoppers & locators (not shown). The sub-assembly 89 of 4 parts (Seat 5, spring 6, retainer 7 and collets 8) is firmly held in the locator 46 to avoid disorder in transit. The disorder if any is checked by a vision system 102 before picking up of this sub-assembly by gripper 65 and the faulty sub-assembly is dumped in the rejection tray (not shown).

Stage 7: Servo system (61) with 2 servo presses and press tools:

Referring to figures 8, 8a, 8b, 8c & 8d, this stage consists of linear servo system 61, which consist of 2 servo presses (62 & 63) (Servo cylinders for pressing operation). The servo presses (62 & 63) have an indexer 64, pick up gripper 65 and a pressing tool 66 mounted on each of them. Pressing tool 66 has a plunger 67 at center which supports sub-assembly (89) from top. The pre-assembled sub-assembly (89) (of seat 5, spring 6, retainer 7 & collets 8) on conveyor pallet 47 is picked up from the pallet 47 by the gripper 65, supported from top by the plunger 67 in press tool 66 and transferred it to the cylinder head 1 on AWC fixture 20, where valves (2, 3) are already inserted by robot-1 (31) and held in position by pusher cylinder 34 as explained earlier in stage 3.

Next, the presses (62, 63) perform the assembly operation of Valves (2, 3) and the pre-assembled sub-assembly 89 by pressing the springs 6 to a pre-defined length. The force on the servo press (62, 63) is continuously monitored with reference to the stroke of the press to confirm adequacy of collets 8 locking. During pressing stroke, servo presses (62 & 63) confirms for spring seat (5) missing, reverse or double assembly by monitoring forces of servo presses. (In case of missing of the seat, less force is observed with respect to pre defined force of servo press. In case of presence of double seat or reverse orientation of seat 5, more force is observed with respect to pre defined force of servo press). Thus errors in the assembly are detected. In case of such errors are detected, the automation system generates alarm of faulty assembly and such component is to be removed by acknowledging alarm by operator & sent for dismantling.

During return stroke, servo presses (62 & 63) monitors whether collets (8) are locked or not. As the pressing tool 66 moves upwards during return stroke, the collets 8 get fully locked in a groove 75 of valve stem 77. At this point the force of servo press reduced almost to zero. If the collets 8 are not locked, the force of servo press will continued and not reduced. This condition is identified by sensing deviation from the pre defined values of force. In this condition, the pressing operation is automatically repeated by the presses (62 & 63) to get correct assembly.

All these 7 stages are described just to explain the functioning of the invention. Number of stages does not limit the invention. Combination of one or more stages and separation of few stages are in the purview of the invention.

The function of pressing tool mechanism for collet assembly in cylinder head is explained in details as below.

Referring to figures 9a, 9b, 9c, 9d, 9e, 9f & 9g.

The Pressing tool mechanism consists of 3 main sub-assemblies,

(A) Pressing tool 66,
(B) Gripper assembly 65,
(C) Orientation mechanism 90

Initially the cylinder head sub assembly (with valves inserted) is supported on AWC fixture 20. The valve (2,3) is in inverted vertical direction and supported from bottom by pusher cylinder 34 which is mounted on robot-1 (30) as explained earlier in stage 3.

Gripper finger 65 of pressing tool 66 picks the spring sub assembly 89 (seat, spring, retainer & collets) from conveyor pallet 47 and places it on the cylinder head cavity for valve fitment.

The spring sub-assembly 89 is supported from top by a special ball point center plunger 67. This plunger 67 locate & hold the loose collet half’s 8 in the retainer 7 securely during (a) pickup of the spring sub assembly from pallet 47, (b) during movement from pick up station to pressing station, (c) during placing of the stack on cylinder head and (d)during pressing operation.

Referring to figure 9, a retainer guide 68 in the pressing tool 66 centralizes the retainer 7 & thus total spring sub-assembly 89 to get aligns with the valve axis 58. The guide 68 of the pressing tool 66 has a special taper profile 71 at bottom corresponding to taper profile of retainer 7. The centralization of retainer 7 is done due to this special taper profile 71 of the guide 68. The centralization of retainer 7 is important for getting equal contact of the valve face 72 with the collets half’s bottom face 73, to raise the collet half’s equally to form diameter for getting entry into this collet assembly. A guide 68 of the pressing tool 66 presses the retainer 7 and spring 6 to predefined length.

The pressing tool operation sequence is explained in the figures 9a to 9g

Fig.9a: Pressing tool 66 moves down, the face 71 of the retainer guide 68 of press tool touches corresponsing face of retainer7. Collet centering plunger 67 & collet pushing plunger 76 of press tool touch on collets 8 from top. Top face 72 of valve stem 77 touches to collets bottom face 73.

Fig.9b: Pressing tool 66 further moves down, the retainer guide 68 of press tool pushes the retainer 7 along with spring 6 downwards and the spring 6 gets compressed. Due to this a radial gap 79 is developed between outer faces of collets 8 and taper surface 70 of retainer guide 68.

Fig. 9c: Pressing tool 66 further moves down, the collets 8 moves sidewise in the gap 79 due to force on collets by plunger 67 of pressing tool, creating space for valve stem 77 to enter between collets 8.

Fig.9d: Further downward movement of pressing tool 66 to predefined stroke results in entry of valve stem 77 inside collets 8 . At this point the collet locking groove 75 on valve stem 77 and the collet locking projection 78 on collets 8 are placed opposite to each other.

Fig.9e: At this point the retainer guide 68 of pressing tool 66 starts moving up while the locking projection 78 of collets 8 are pushed in the groove 75 of valve stem 77 by force exerted by the taper face of retainer 7 while moving upwords.

Fig.9f: Further upward movement of retainer guide 68 of pressing tool 66 releases the pressure on retainer 7. Retainer 7 moves slightly up due to spring force & collets 8 further gets pushed in the groove 75 of valve stem 77, due to taper on retainer 7. At this stage collets 8 are locked in the groove75 of valve stem 77. Spring 6 and retainer 7 are also locked in this position. Further collet pusher plunger 76 maintains contact with collets 8 from top to support the collets 8 till it gets fully lock.

Fig.9g: Collets 8 are fully locked, pressing tool 66 is at fully upward condition, electrical gripper 65 fingers return to its original position. This completes the valve assembly operation.

Referring to figure 8e, the Orientation mechanism 90 consists of pneumatic indexer 98 with gears which are housed in steel block with ball bearings. One gear 99 from indexer shaft connects with the gear 100 fixed on housing, on which pick-up gripper 65 is attached. It rotates the electric pick up gripper assembly 65 around pressing axis 69, so as to avoid fouling of the gripper assembly 65 with the projected portion of cylinder head 1 as well as clamp on the cylinder head. This is required when the cylinder head changes from intake pressing axis to exhaust pressing axis and vice versa.

Another important use of this design is to achieve exact orientation required for the gripper fingers 65 to open in the cylinder head cavity for placing the spring assembly smoothly.

All above stages are arranged in a compact layout.

This compact layout may be arranged in a suitable shape; for example a rectangular space (80) as seen from top. Refer figure 10. As per one embodiment of the invention, the size of rectangle (80) is approximately 5.4 meter X 3.3 meters. Automatic work changer (AWC) 20 is placed at one corner (81) of the rectangle (80). The servo valve stacker (30) is placed at another corner (83) adjacent to one small side (82) of rectangle (80) and near the AWC (20). Robot 1 (31) is placed between AWC (20) and servo valve stacker (30) near the valve stacker (30). Robot 2 (41) is placed next to the valve stacker (30) and adjacent to one big side (84) of rectangle. Feeders (42 & 43) are placed between robot 2 (31) and big side (84) of rectangle (80). Robot 3 (51) is placed next to the robot 2 (41) adjacent to the same big side (84) of rectangle and at another corner (85) of rectangle. Feeders (56 & 57) are placed between robot 3 (51) and big side (84) of rectangle (80). The conveyer (55) is placed at central part of rectangle. Vision system 101 is place above the conveyer 55 near robot II (41) and vision system 102 is placed above conveyer 55 near pick-up gripper 65. Servo system (61) with press tools (62 & 63) are arranged above the AWC (20) in the rectangle (80). All control panels 103 and main PLC (programmable logic controller) panel 104 are arranged near the small sides (82 & 86) of rectangle 80.

As the robot 1 (31) is located between AWC (20) and valve stacker (30), it picks the valves (2 & 3) from valve stacker (30) and insert it in cylinder head (1) on AWC (20). Sub-assemblies (89) of spring (6), seat (5), retainer (7) & collets (8) are done by robot 2 (41) at another corner (85) of rectangle (80) and these sub-assemblies (89) are brought closed to the AWC (20) by conveyer (55). The servo pressing tool 66 is arranged above AWC (20) and near conveyer (55) so that the gripper (65) quickly picks the sub-assemblies (89) from conveyer (55) and place it on cylinder head (1) on AWC (20), Then pressing tool (66) which is located above AWC (20) perform the pressing operation on cylinder head (1) on AWC (20).

All feeders (23, 24, 42, 43, 56 & 57) are placed at one big side (84) of rectangular space (80) so that refilling of components in feeders can be done easily by an operator.

A conveyer (55) consist of plurality of pallets. Various components/ sub-assemblies are mounted on these pallets sequentially and are guided on conveyer to next desired position. Lastly a complete sub-assembly 89 is pick up from pallet by the robot and empty pallets are guided on conveyer 55 for next position. As this is a close loop conveyer, it saves space of the layout.

All control panels are arranged such that all are accessible from outside of the automation system for easy maintenance.

Thus this compact layout of fully automated operation requires only one man for loading/ unloading of cylinder heads and feeding all components from one side. No additional manpower and equipments are required for material movement as all material is stored at one place within layout of the system.

By implementing this automation system, the manpower required is reduced to one man as compared to four men in manual system for producing 1200 cylinder head assemblies in one shift. Rejection of assemblies also reduced to 2% from 7%.

Modifications and variations to the secondary air injection system described may be apparent to the skilled reader of this specification. Such modifications and variations are deemed within the scope of the present invention. The applicant intends to rely on the provisional specification and drawings annexed to the provisional specification.
,CLAIMS:1. The cylinder head assembly automation system comprising plurality of stages for picking up of items, sub assembly and final assembly wherein the said stages are provided with vision systems, robotic devices with a pre-programmed sequence of operation/ movement; the said vision systems capable of capturing the images of assembly parts and provide this input to said robotic devices to perform desired activity.

2. The cylinder head assembly automation system as claimed in claim 1 comprising automatic work changer (20) which consists of atleast one fixture(11) for mounting atleast one cylinder head (13) wherein the said fixture/s provided with plurality of servo motors (15,16) for performing linear and rotary movement of fixture/s.

3. The cylinder head assembly automation system as claimed in claim 2 wherein the fixtures are mounted of indexer (17); the said indexer (17) is provided with a motor (16) to index/ rotate the fixtures (11,12) in various desired positions.

4. The cylinder head assembly automation system as claimed in claim 1 comprising servo stacker module (30) which consists of plurality of servo feeders (23,24) and pallets (21) wherein atleast one pallet (21) is moved in vertical direction and atleast one pallet (21) is moved in horizontal direction by servo feeders (23,24).

5. The cylinder head assembly automation system as claimed in claim 4 comprising a vision system (22) which captures image of components stored in the pallets (21); the said vision system (22) analyzes the image for predefined dimensions and orientation of components for selecting correct component and further identify the position of correct component in the pallet (21) and communicate this position to robot (31) for pickup.

6. The cylinder head assembly automation system as claimed in claim 5 comprising a robot (31) which has at least one gripper (32) which, acting on the feedback from the vision system (22), picks up the correct component from the pallet (21) and moves it to desired position.

7. The cylinder head assembly automation system as claimed in claim 1 comprising feeder system; the said feeder system comprises a storage tray (91) and atleast one vibratory tray (91a) to store and feed the components to robot 41.

8. The feeder system of the cylinder head assembly automation system as claimed in claim 7 wherein storage tray (92) is a vibratory tray.

9. The feeder system of the cylinder head assembly automation system as claimed in claim 7 wherein a vibratory tray (91a) has linear grooves (91b) in which the components are aligned in the direction of grooves (91b) when the tray is vibrated.

10. The cylinder head assembly automation system as claimed in claim 1 comprising a robot (51) which has plurality of grippers (52.53) to hold and pick the parts wherein atleast one gripper (52) has provided a hollow slot (97) on one of its side surface to facilitate operation of another gripper (53) through the said slot (97).

11. The cylinder head assembly automation system as claimed in claim 1 comprising atleast one conveyer (55) which moves the pallets (47) containing components and sub-assembly of components to desire positions; the said sub-assembly contains seat (5), spring (6), retainer (7) and collets (8).

12. The cylinder head assembly automation system as claimed in claim 11 comprising a vision system (22a) which captures image of sub-assemblies stored on the pallets (47) of conveyer (55); the said vision system (22a) analyzes the image to identify the correct assembly of sub-assembly on the pallet (47) and communicate to robot 51 for pickup.

13. The cylinder head assembly automation system as claimed in claim 1 comprising atleast one servo pressing tool (61) which performs the assembly operation of Valves and the pre-assembled sub-assembly in the cylinder head (1) by pressing the springs (6) to a pre-defined length so that collet locking groove (75) on valve stem (77) and the collet locking projection (78) on collets (8) are placed opposite to each other.

14. The servo pressing tool (61) of the cylinder head assembly automation system as claimed in claim 13 comprising a at least one ball point center plunger (67) which locates & holds the collet halves (8) in the retainer securely during (a) pickup of the sub assembly from pallet, (b) during movement of sub-assembly from pallet to cylinder head, (c) during placing of the sub-assembly on cylinder head and (d) during pressing operation.

15. The servo pressing tool (61) of the cylinder head assembly automation system as claimed in claim 13 comprising at least one collet pusher plunger (76) which supports the collets (8) from top during assembly operation.

16. The servo pressing tool (61) of the cylinder head assembly automation system as claimed in claim 13 comprising a retainer guide (68) provided with a taper profile at its outer periphery at its lower end; the said taper surface corresponding to taper profile of top surface of retainer (8) for centralizing the retainer (8) during assembly operation.

17. The servo pressing tool (61) of the cylinder head assembly automation system as claimed in claim 13 comprising an orientation mechanism (90) which consists of atleast one motor and gear (99) to rotate the press tool along with gripper (65) around axis (69) of the pressing tool in desired position, so as to avoid fouling of the gripper (65) with the projected portion of cylinder head and its holding fixture during assembly operation.

18. The cylinder head assembly automation system as claimed in any above claims is arranged in a compact layout wherein automatic work changer (20) is placed at one end of the layout. The servo stacker module (30) is placed at another end opposite to the automatic work changer (20). Feeders (24) are placed at another end of the layout adjacent to servo stacker module (30). The conveyer (55) is placed at another end of the layout adjacent to automatic work changer (20). One Robot (31) is placed between automatic work change (20) and servo valve stacker (30). Other robots (41) are placed between feeders (56, 57) and conveyer (55). Vision systems (22a, 22b, 22c, 22d) are place above the servo stacker module (30), vibratory trays (91a, 92a, 93a) and conveyer (55) in the layout.

19. The layout of the cylinder head assembly automation system as claimed in claim 18 where in plurality of feeders (56,57) and valve stacker (30) are placed at same side of layout adjacent to each.

20. The layout of the cylinder head assembly automation system as claimed in claim 18 wherein the conveyer (55) is of close loop type.

21. The layout of the cylinder head assembly automation system as claimed in claim 18 where in plurality of control panels (103) are placed at outer side of layout.

22. A method of cylinder head assembly comprising steps of
a. loading a cylinder head on automatic work changer,
b. feeding the valves from stacker module to robot by moving the trays in horizontal and vertical direction by servo motors,
c. identifying the correct valve and its position in the trays by vision system and communicating this to robot for picking up the valve,
d. picking up the correct valve by robot and placing it on the cylinder head valve guide,
e. feeding the sub-assembly components from respective storage trays to respective vibratory trays by vibration or gravity,
f. identifying the correct sub-assembly components and its position in the trays by vision system and communication this to respective robot for picking up the correct sub-assembly components,
g. picking up the correct sub-assembly components by receptive robot and placing it on a locator provided on pallet of conveyer to make sub-assembly of these components,
h. moving the pallet by conveyer near the servo press tool,
i. checking the correct sub-assembly of components by vision system and communicating it to servo press,
j. picking up of correct sub-assembly by servo press tool and placing it on cylinder head valve stem, and
k. pressing of sub-assembly on cylinder head by servo press tool.

23. A method of cylinder head assembly by servo press tool comprising steps of
a. initial pressing of sub- assembled components by servo press tool to creates a radial gap between outer faces of collets and taper surface of retainer guide allowing the collets halves to move sidewise in the gap and thus creating space for valve stem to enter between collet halves,
b. further pressing by servo press tool to predefined stroke making entry of valve stem inside collet halves to bring collet locking groove on valve stem and the collet locking projection on collets opposite to each other, and
c. reverse movement of press tool allows locking of projection of collets in the groove of valve stem due to force exerted on collet halves by the taper face of retainer, thus completing the cylinder head assembly.