Claims:We claim:

1. A mechanism for producing sheet metal blanks for making body panels of an automotive vehicle, the mechanism comprises

• an upper die;

• a stripper pad;

• a lower die;

• a coil feeding unit comprising:

(a) an uncoiling unit for uncoiling the coil steadily and continuously;

(b) a coil support unit to support the coil fed between the dies;

(c) a coil guide unit;

(d) a pinch roller;

(e) a coil washing unit;

(f) a coil looping mechanism;

(g) a coil shearing unit for producing metal blanks for body panels;

(h) blank chutes collecting the blanks produced and directing the same towards blank conveyor/s; and

(i) scrap chutes collecting the scrap pieces generated and directing the same towards scrap conveyor/s,

• blank conveyor/s for moving blanks dropped thereon from the blank chutes towards blank stacking system;

• blank stacking system; and

• scrap conveyor/s for moving scrap pieces dropped thereon from the scrap chutes towards blank scrap disposal system;

wherein the coil looping mechanism forms a coil loop to feed the coil for compensating the intermittent blanking press strokes to facilitate a continuous blanking operation.

2. Mechanism as claimed in claim 1, wherein the upper die comprises at least two pairs of profiled male cutters corresponding to the blank to be produced for making a respective panel of the automotive vehicle body, and the lower die comprises at least two pairs of profiled female cutters for making cavity corresponding to the blank to be produced for making a respective panel of the automotive vehicle body, wherein the cutters are fitted mutually opposed to form opposed blank cavities optimized in the metal sheet being processed.

3. Mechanism as claimed in claim 1, wherein the metal sheet moves by a distance equal to pitch distance after every blanking operation, in which two blanking out cutters are disposed mutually opposed.

4. Mechanism as claimed in claim 1, wherein the upper die is provided with guide bushes therein and the stripper pad is guided and held by the upper die.

5. Mechanism as claimed in claim 4, wherein the lower die is provided with guide pins for guiding the upper die.

6. Mechanism as claimed in claim 2, wherein each pair of cutters comprises a steel cutter for making blanks and a scrap cutter for cutting out scrap pieces from the metal sheet coil.

7. Mechanism as claimed in claim 2, wherein the upper die comprises:

• an idle pilot station holding the metal sheet;

• a respective pair of upper steel cutter and upper scrap cutter;

• a piercing punch provided on the die front side with the number of pilot piercing holes varying according to the coil size and the required accuracy;

• a pilot punch for locking the coil movement thereby and for guiding the metal sheet between pilot holes on aligning the upper die with lower die;

• a pressure forcing element, preferably a coil spring;

wherein the pressure forcing element applies a pressure for holding the coil and the piercing punch pierces pilot holes through the coil in cooperation with the die cavity and the upper steel cutter pierces the coil to cut the first blank in combination with the lower steel cutter by means of a predefined cutting clearance provided with respect to the upper steel cutter for producing burr-free blanks.

8. Mechanism as claimed in claim 2, wherein the lower die comprises a lower shoe for carrying a lower cutter, having a profile similar to the profile of the sheet metal blank to be produced for making a respective automotive body panel; wherein the lower die is a single unit, preferably a plurality of steel cutters bolted together.

9. Mechanism as claimed in claim 2, wherein the coil guide unit comprises a fixed roller at one end thereof and swinging roller at the other end thereof to maintain the coil center for adjusting the smallest variation in the coil width.

10. A method for producing sheet metal blanks for making body panels of an automotive vehicle using the mechanism as claimed in claims 1 to 9, wherein the method is used to produce blanks with or without scrap.

11. Method as claimed in claim 10, wherein the sheet metal blanks are collected at the sides of the die in case of method involving blanks production with scrap.

12. Method as claimed in claim 10, wherein the scrap is cut at the last stage on conveyor of blanking process in case of method involving blanks production without scrap.

13. Method as claimed in claim 10, the method comprising the steps of:

• feeding a sheet metal coil steadily and continuously into the die unit from an uncoiling unit of the coil feeding unit;

• supporting the fed coil by the coil supporting unit;

• guiding the supported coil by means of the coil guide unit;

• making a first die stroke once coil moves by pitch distance equals at the end of the first stage by holding the coil by the pressure applied the stripper pad;

• making a pilot hole by piercing through the coil by means of piercing punch before completing the first stroke;

• pressing the upper die into the coil to cut the blank by blanking in cooperation with the lower steel cutter maintaining a predefined cutting clearance with respect to the upper steel cutter for producing burr-free sheet metal blanks;

• moving the first blank dropped in the blank chute by the blank conveyor towards the die side;

• Manually stacking the first blanks sideways;

• Retracting the upper upwards and releasing the pressure applied by the stripper pad on the coil;

• Moving the coil forward by pitch distance and ensuring locking the coil movement by a pilot punch moving downward with the upper die and aligning with the pilot hole pierced earlier;

• Moving the coil further by pitch distance;

• Moving the upper die moves downward and aligning with the guide unit;

• Holding the blanked coil sheet by applying pressure by the stripping pad and aligning the upper steel cutter and lower die cutters;

• Making a second stroke to cut a second blank and dropping in the blank chute for the moving the same by the blank conveyor towards the die side; and

• Manually stacking the first blanks sideways.

Dated: this day of 27th October 2017. SANJAY KESHARWANI
APPLICANT’S PATENT AGENT , Description:FIELD OF INVENTION

The present invention relates to forming vehicle bodies from sheet metals. In particular, the present invention relates to a mechanism for producing complicated blanks as part of vehicle bodies in a single step method. More particularly, the present invention relates to a faster method for producing complex sheet metal blanks for making vehicle bodies, however with substantially reduced scrap generation.

BACKGROUND OF THE INVENTION

Normally, a vehicle body is made by joining several sheet metal panels. These panels are formed by either forming or drawing process. In both the process, the input material is sheet metal blank, which varies from rectangular, square to any shape or profile. Generally, the straight-line sheet metal blanks are cut by swing dies for shaping e.g. rectangular, square, trapezoidal shapes etc.

But sheet metal blanks having complicated shapes can be produced only by using special blanking die for each such shape or by laser cutting of blanks. However, the laser cutting process used for large volume production of blanks is quite costly, time-consuming and also requires large initial investment.

PRIOR ART

US 20150020358 A1 discloses a method of motor vehicle sheet blanking and a system of the same, wherein the blanking method comprises: firstly, nesting for motor vehicle sheet material, and cutting it into group sheets with a shape and size confirmed by the multi length of the sheet; next, designing a backing die depending on scraps to be cut from the group sheet, and hollowing in areas corresponding to blanking openings in the backing die, in which the dimensions of the blanking openings are greater than that of the actual scraps to be cut; then, placing a group sheet onto backing die; laser cutting of group sheet based on the motor vehicle sheet shape, the cut scraps dropping through blanking openings in the backing die on a scrap conveyor belt underneath; stacking cut sheets. It effectively processes scraps cut from sheets to improve blanking efficiency. The sheet is nested by blank shape. A backing die is produced for scrap shedding. When the sheet is cut to the blank size by laser, scrap comes out of backing die openings and the blank sheet stacking is done by robots.

This disclosure does not focus on mechanical blank production method with very high SPM. Moreover, the complexity and size of the blanks affects the cost and time for each blank production.

US4362078 A discloses a method of blanking wherein an endless V-shaped groove of desired contour is formed on at least one of the top and bottom sides of a material sheet. The groove is shaped so that the external side thereof is at a right angle to the groove-cut surface of the sheet. A blank having the desired contour is then cut out of the sheet along the right-angled external side of the groove.

The object of this disclosure is to cut out the blank of desired shape with high precision by forming an endless V groove on the cutting periphery of the upper and lower cutting steel. The invention does not concern the method of blank production, but relates to tangential cutting of blank with negligible or no bridge between two blanks.

US7600312 A1 discloses a progressive die assembly and method for manufacturing lamina stacks from a strip of substantially planar material, in which at least some of the individual laminas are formed with portions which extend from, or are otherwise not within, the plane of the material strip. The die assembly includes die stations having punches for punching features substantially within the plane of the strip corresponding to individual laminas, such as lamina profiles and lamina interlock features. Additionally, the die assembly also includes at least one forming station which includes forming tool that can be a selectively actuated and is configured to form a lamina portion in the strip which is disposed outwardly of the strip plane, such as by bending a portion of the strip. The die further includes a blanking station including a blanking punch for blanking individual laminas from the strip, and at least one staking punch for engaging lamina interlock features to interlock a blanked lamina with previously blanked laminas in a choke cavity to form an interlocked lamina stack. This invention provides a progressive die assembly and method for manufacturing lamina stacks from a strip of substantially planar material, in which at least one of the individual laminas is formed with portions which extend from, or are otherwise not within, the plane of the material strip.

The invention does not concern the method of blank production, but relates to forming and blanking stages in the process with one outline cutting operation in the last stage.

DISADVANTAGES WITH THE PRIOR ART

It is well-known that for making vehicle bodies two types of sheet metal blanks are required to be produced, i.e. sheet metal blanks with or without scrap generation. An automated blanking line is used for metal blanks not generating scrap from the metal sheet fed continuously thereon. As the name suggests, the method involving scrap less blanks, does not generate any scrap. Here, the blanks are nested in the sheet width and length such that no scrap is generated with the production of each sheet metal blank. A manual blanking line is generally used to produce blanks generating scrap.

However, the limitation with the manual blanking line is the requirement for manually feeding a metal sheet of a particular length, e.g. 2 meters and for every stroke, only one blank is produced and then sheet should be moved forward in the blanking die by pitch distance. This movement of the sheet on die is precisely controlled by the pilot hole pierced in the sheet when first blank is produced.

OBJECTS OF THE INVENTION

Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:

An object of the present invention is to provide an improved high-speed automation blanking line for producing sheet metal blanks.
Another object of the present invention is to provide a high-speed automation blanking line for producing sheet metal blanks with an improved die strip layout.

Still another object of the present invention is to provide a high-speed automation blanking line for producing sheet metal blanks to reduce scrap generation.

Yet another object of the present invention is to provide a low-cost high-speed automation blanking line for producing sheet metal blanks of complex shapes.

A further object of the present invention is to provide a high-speed automation blanking line for producing sheet metal blanks of complex shapes at high speed.

A yet further object of the present invention is to provide a high-speed automation blanking line for producing sheet metal blanks of accurate size and profile.

These and other objects and advantages of the present invention will become more apparent from the following description, when read with the accompanying figures of drawing, which are however not intended to limit the scope of the present invention in any way.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a mechanism for producing sheet metal blanks for making body panels of an automotive vehicle, the mechanism comprises

• an upper die;

• a stripper pad;

• a lower die;

• a coil feeding unit comprising:

(a) an uncoiling unit for uncoiling the coil steadily and continuously;

(b) a coil support unit to support the coil fed between the dies;

(c) a coil guide unit;

(d) a pinch roller;

(e) a coil washing unit;

(f) a coil looping mechanism;

(g) a coil shearing unit for producing metal blanks for body panels;

(h) blank chutes collecting the blanks produced and directing the same towards blank conveyor/s; and

(i) scrap chutes collecting the scrap pieces generated and directing the same towards scrap conveyor/s,

• blank conveyor/s for moving blanks dropped thereon from the blank chutes towards blank stacking system;

• blank stacking system; and

• scrap conveyor/s for moving scrap pieces dropped thereon from the scrap chutes towards blank scrap disposal system;

wherein the coil looping mechanism forms a coil loop to feed the coil for compensating the intermittent blanking press strokes to facilitate a continuous blanking operation.

Typically, the upper die comprises at least two pairs of profiled male cutters corresponding to the blank to be produced for making a respective panel of the automotive vehicle body; the lower die comprises at least two pairs of profiled female cutters for making cavity corresponding to the blank to be produced for making a respective panel of the automotive vehicle body, wherein the cutters are fitted mutually opposed to form blank cavities optimized in the metal sheet being processed.

Typically, the metal sheet coil moves by a distance equal to pitch distance after every blanking operation, in which two blanking out cutters are disposed mutually opposed.

Typically, the upper die is provided with guide bushes therein and the stripper pad is guided and held by the upper die.

Typically, the lower die is provided with guide pins for guiding the upper die.

Typically, each pair of cutters comprises a steel cutter for making blanks and a scrap cutter for cutting out scrap pieces from the metal sheet coil.

Typically, the upper die comprises:

• an idle pilot station holding the metal sheet;

• a respective pair of upper steel cutter and upper scrap cutter;

• a piercing punch provided on the die front side with the number of pilot piercing holes varying according to the coil size and the required accuracy;

• a pilot punch for locking the coil movement thereby and for guiding the metal sheet between pilot holes on aligning the upper die with the lower die;

• a pressure forcing element, preferably a coil spring;

wherein the pressure forcing element applies a pressure for holding the coil and the piercing punch pierces pilot holes through the coil in cooperation with the die cavity and the upper steel cutter pierces the coil to cut the first blank in combination with the lower steel cutter by means of a predefined cutting clearance provided with respect to the upper steel cutter for producing burr-free blanks.

Typically, the lower die comprises a lower shoe for carrying a lower cutter, having a profile similar to the profile of the sheet metal blank to be produced for making a respective skin panel; wherein the lower die is a single unit, preferably a plurality of steel cutters bolted together.

Typically, the coil guide unit comprises a fixed roller at one end thereof and swinging roller at the other end thereof to maintain the coil center for adjusting the smallest variation in the coil width.

In accordance with the present invention, there is also provided a method for producing sheet metal blanks for making body panels of an automotive vehicle using the aforesaid mechanism, wherein the method is used to produce blanks with or without scrap.

Typically, the sheet metal blanks are collected at the sides of the die in case of method involving blanks production with scrap.

Typically, the scrap is cut at the last stage on conveyor of blanking process in case of method involving blanks production without scrap.

Typically, the method comprises the steps of:

• feeding a sheet metal coil steadily and continuously into the die unit from an uncoiling unit of the coil feeding unit;

• supporting the fed coil by the coil supporting unit;

• guiding the supported coil by means of the coil guide unit;

• making a first die stroke once coil moves by pitch distance equals at the end of the first stage by holding the coil by the pressure applied the stripper pad;

• making a pilot hole by piercing through the coil by means of piercing punch before completing the first stroke;

• pressing the upper die into the coil to cut the blank by blanking in cooperation with the lower steel cutter maintaining a predefined cutting clearance with respect to the upper steel cutter for producing burr-free sheet metal blanks;

• moving the first blank dropped in the blank chute by the blank conveyor towards the die side;

• Manually stacking the first blanks sideways;

• Retracting the upper upwards and releasing the pressure applied by the stripper pad on the coil;

• Moving the coil forward by pitch distance and ensuring locking the coil movement by a pilot punch moving downward with the upper die and aligning with the pilot hole pierced earlier;

• Moving the coil further by pitch distance;

• Moving the upper die moves downward and aligning with the guide unit;

• Holding the blanked coil sheet by applying pressure by the stripping pad and aligning the upper steel cutter and lower die cutters;

• Making a second stroke to cut a second blank and dropping in the blank chute for the moving the same by the blank conveyor towards the die side; and

• Manually stacking the first blanks sideways.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will be briefly described with reference to the accompanying drawings.

Figure 1 shows a conventional arrangement of automated blanking line. The sheet metal has a straight-line profile, which is to be cut into sheet metal blanks for producing vehicle body components.

Figure 2 shows a conventional arrangement of manual blanking line.

Figure 3a shows a method of producing sheet metal blanks and involving scrap generation for each blank produced.

Figure 3b shows the sequence of operations during the sheet metal blank production method of Figure 3a.

Figure 4a shows the shows conventional method of producing sheet metal blanks on an automated blanking line by using a metal sheet coil and scrap generated between the blanks produced.

Figure 4b shows the method of Figure 4a for producing sheet metal blanks performed on an automated blanking line with second and third scrap generation.
Figure 5a shows a schematic diagram of the coil feeding unit 100 for performing the overall process devised in accordance with the present invention.

Figure 5b shows die-strip layout 100 for high-speed automated blanking line configured in accordance with the present invention.

Figure 6a shows the perspective view of the lower die of the automated blanking line 200 of Figure 5b and the constructional features thereof.

Figure 6b shows the perspective view of the upper die of the automated blanking line 200 of Figure 5b and the constructional features thereof.

Figure 7 shows the perspective view of the stripper pad required in the automated blanking line of Figure 5b for holding and pressurizing the metal sheet in the position during the blank cutting/blanking process.

DETALED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following, the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention in any way.

Figure 1 shows a conventional arrangement of automated blanking line. The sheet metal has a straight-line profile SL, which is to be cut into sheet metal blanks B for producing vehicle body components. In each cycle, the coil with a width w, pitch P is fed with a feed rate F and a predefined blanking press-stroke is used to cut it into a first sheet metal blank 1 and the remaining half portion of the sheet metal forms the other blank 2 simultaneously. The number of 50-60 blanks produced per minutes by this method is much higher than the manual blanking line due to the rate of 25-30 strokes/minute, which also depends on the blank shape to be cut. Here, one blank is collected on the front side conveyor and the other blank is collected at the side, either manually or on the side conveyor. This type of blank cutting mainly requires that both blanks should have the same profiles and width of the blank should be equal to the coil width fed. Also, the width of the blank should be in straight line and no scrap should get be generated in this process.

Figure 2 shows a conventional arrangement of manual blanking line. The metal sheet of specific length L and width w is manually fed into the die. This method is similar to the automated blanking line of Fig.1. However, the main disadvantage of this method is low number of blanks produced per minute, e.g. about 3-5 SPM than the automated blanking line of Fig.1. Since each stroke produces 2 blanks, only 6-10 blanks/minute are produced here and both the blanks are collected manually. This blanking line mainly requires a manual feeding of the sheet metal for performing blanking operation thereon. Moreover, the width w and length L of the sheet fed also impacts sheet weight and thus affects the number of blanks (6-10) produced. Each sheet produces a plurality of blanks, so sheets should be fed consecutively after each consumed sheet. Moreover, the blank width should be in straight line and no scrap is generated. However, the main differences between the arrangements of Fig. 1 and Fig. 2 are given below:

i. Automated blanking line can produce 25-30 blanks per minute, whereas the conventional manual blanking line can produce only 6-10 blanks per minute.

ii. Automated blanking line produces continuous blanks until whole coil is exhausted, whereas the conventional manual blanking line requires a new sheet to be fed after only a few blanks are produced from a single metal sheet.

iii. In conventional manual blanking line, human ergonomics is also to be considered for stacking etc. e.g. sheet weight, size; blank weight, size. This is no required at all in automated blanking line.

iv. In conventional manual blanking line, stacking of blanks produced is done manually; whereas in automated blanking line, it is done either by stacking robots if blanks produced are placed on conveyor. If blanks are not placed on conveyor of automated blanking line and come out sideways from the die, the blanks are collected manually.

Figure 3a shows a method of producing sheet metal blanks using a blanking die with die outline D and involving generation of scrap 25 for pair of blanks 1, 2 produced. The volume of scrap 25 generated depends on the minimum bridge/hold of material required to be kept between two blanks 1, 2. If the material sheet is oversized, each sheet generates scrap 26 at its end. The volume of scraps 25, 26 is significant, considering the large volume of blanks B produced from multiple material sheets and each sheet contributing in generating sheet metal scraps 25, 26. The blanks B produced are collected manually. However, the disadvantages associated with this method are as given below:

• Scrap is generated due to the bridge kept between two blanks in every sheet.

• Any oversized sheet generates sheet scrap at the end thereof.

• Sheet rotation and feeding is manual and needs precise manual handling.

• Sheet metal blank production from metal sheets is a repetitive and tedious work and thus causes operator’s fatigue.

• Scrap type blanks have limitations in terms of size and shape for production on a conventional manual blanking line due to completely manual handling.

• For big-sized blanks involving scrap generation, the automated blanking line is a must, because this activity substantially affects the yield from input sheet material coil. Big sized blanks are also difficult to handle manually due to sagging or bending of blank possible during their handling, which may hamper its acceptance for subsequent processing.

• Any human intervention is more prone to occurrence of accidents, which may often be fatal.

Therefore, the conventional manual blanking line with scrap generation has very limited scope, in which the sheet size (L x w) to be fed should be easy to handle, sheet weight should be lesser and blanking operation should be easily carried by an operator. The blank shape should ergonomically less tiring and should not be prone to damage during handling thereof. Further, the size of the produced blanks should be easy to be carried by an operator.

Figure 3b shows the sequence of operations during the sheet metal blank production method of Figure 3a. It includes step 12 of cutting first blank, followed by taking out sheet at the rear side of the die at step 14. Subsequently, a rotation 1 of the sheet is to change sides longitudinally at step 20, followed by a second rotation is for changing sides transversely at step 16. Now, a second rotation 2 is done at step 18 and blank 2 is cut at step 20 to complete blanking of this sheet to cut-off and disposing off the scrap pieces 25, 26.

Figure 4a shows the shows conventional method of producing sheet metal blanks on an automated blanking line by using a metal sheet coil having its width W equal to blank width w and scrap 27 is generated between two blanks so produced. Thus, the steel cutters used for blanking are made in the shape of scrap 27 and blank B is produced after each stroke and collected on the press conveyor provided at the rear side RS of the blanking press and stacked by stacking robots provided at the end of conveyor line (not shown). The sheet metal coil moves forward by a coil feed rate F and a pitch P for each stroke to produce blanks B. The scrap sheet 27 fall down through the scrap chute (not shown) on the scrap conveyor. Here, the produced blanks B are moved by the conveyor and are stacked by stacking robots.

However, some of the disadvantages of this method are:

• Only one blank/stroke produced.

• Scrap its produced in every stroke of the blanking press, so each blank generates scrap.
• The cumulative scrap weight for a coil length is very high, thus considerably reduces the blank yield.

• Unlike manual line, rotation of the sheet not possible to attain the yield optimization.

• Only 25-30 blanks/minute are produced, which is very low.

• Blank shape generating scrap along the width of the coil reduces the number of cutting stages in the die.
Figure 4b shows the method of Figure 4a for producing sheet metal blanks performed on an automated blanking line with first 28, second 29 and third scrap 30 generation. Since the blank shape generates different types of scrap along its width, the scrap cutting should be distributed in a plurality of die stages. For example, scraps 28 and 29 are cut in stage I, which move towards the scrap conveyor through the scrap chute (not shown) and a bridge is left between two blanks 2, 3 at the end of stage I end leaves a bridge between two blanks as third scrap 30. At stage II, this bridge is cut and the first blank 1 moves towards the conveyor disposed at the die rear side RS. Subsequently, the metal coil moves forward by pitch P and the aforesaid process repeats for each die stroke. However, the disadvantages with this method are as follows:

• In order to get the blank in final stage, scraps need to be cut successively in every stage. Thus, this blank is the result of scrap cutting.

• Each stroke of the die produces one blank.

• Each blank contributes the scrap.

Figure 5a shows a schematic diagram of the coil feeding unit 100 for performing the overall process developed in accordance with the present invention. In this method, the coil 110 is loaded on the uncoiler unit and centered. Thereafter, it is unfolded to be passed through the pinch roller 120 to eliminate the curvature and to straighten the coil. If blanks to be produced require washing, metal sheet is passed through the washing unit 130. Generally, the washing of blanks is required for skin panels of the automobile. After washing, a coil loop 140 is formed for coping with the velocity of uncoiler and press stroke. The die requires intermittent feeding of the material, whereas the uncoiler 110 uncoils the coil steadily and continuously. This gap between the input at the die and output at uncoiler 110 is maintained by this loop. For example, if the die requires 2.5 meters of sheet for each stroke and each blanking stroke requires 5 seconds, then uncoiler 110 continuously rotates and unfolds 2.5 meters of coil in 5 seconds. After coil loop 140, it is passed on to the shear unit 150 to cut blanks by a blanking die. Finally, the blanks produced are dropped on a blank conveyor 160 and blanks are stacked in the step of blank stacking 170.
Figure 5b shows die-strip layout 200 for high-speed automated blanking line configured in accordance with the present invention. It includes four stages, i.e. stage I, II, III and IV. The assembly of this die arrangement includes a stripper pad 250 (Fig. 7) guided and held by an upper die 240. The upper die 240 is guided in a lower die 230 (Fig. 6b) by means of guide pins 215 in the lower die 230 (Fig. 6a) with guide bush 248 in the upper die 240. Here, sheet metal coil guided by coil guides 222, 224 and supported by coil support system 220 is fed into the die by a coil feeding unit (not shown). At stage I, the coil travels by pitch distance P and first die stroke occurs to cut metal sheet for producing the first blank B1. At stage II, the blanked sheet moves further by pitch distance P ensured by locking the coil movement by a pilot punch. The coil remains idle at stage III and no cutting occurs. At stage IV, the sheet moves further by pitch distance and the second die stroke occurs to cut metal sheet for producing the second blank B2. Further, scrap pieces s1, s2, s3 and s4 are cut by the scrap cutter cutting edges S1, S2, S3 and S4. These cut scrap pieces s1, s2, s3 and s4 are moved to the scrap conveyor by means of scrap chutes. As the coil starts feeding continuously and moves forward with pitch distance, two blanks B1 and B2 are cut by two different cutting die cavities and blanks B1, B2 pass through the respective roller conveyor.

Figure 6a shows the perspective view of the lower die 230 of the automated blanking line 200 of Figure 5b and depicting the constructional features required for working the present invention. It consists of a lower shoe 202 carrying a lower cutter 204, the shape of which is similar to the shape of the blank B to be produced. This lower steel construction may be a single unit, or multiple steels bolted together. The scrap cutter 206 at the extreme rear side of the die are arranged to cut scrap from the coil to produce the blank. At this last station, all scrap pieces generated during the blanking process are cut and moved through scrap chutes 208, 226. After cutting the blank by using blank cutter, it is moved through roller chutes 216, 218 to the sides and collected manually. On feeding the coil into the die, it is supported by coil support unit 220 to avoid any uneven curvature formed on the coil. The coil center is maintained by coil guide unit, which helps to adjust even a small variation in the coil width. This unit consist of a fixed roller 222 at one end and swing type of roller 224 at the other end. The guiding unit 222 and 224 support the metal sheet from variation in coil width.

Figure 6b shows the perspective view of the upper die 240 of the automated blanking line 200 of Figure 5b depicting the constructional features of the present invention. An idle pilot station holds the sheet due to the pressure applied by the pressure forcing element (Coil spring 234 in this case) on stripper pad 250 (Fig.7). Upper steel cutter 242 and upper scrap cutter 244 246 etc. are mounted in the upper die 240. A piercing punch 246 (Fig. 6a) is provided on the die front side FS and the number of pilot piercing holes is varied based on coil size and the desired accuracy. A pilot punch 232 guides metal sheet in pilot hole 214 when upper die aligns with lower die 230. The coil is held due to the pressure applied by stripping pad and a pilot hole is pierced through the coil using a piercing punch and die cavity 246 and the upper steel cutter 242 pierces the coil to cut the first blank B1 with the lower steel cutter having a predefined cutting clearance with respect to the upper steel cutter 242, sufficient to produce burr-free blanks. On moving the upper die 240 upward, the pressure is released from the initially blanked sheet to move forward in the die by pitch distance. On moving the blanked sheet further by pitch distance ensured by locking the coil movement by a pilot punch 232, which moves downward with the upper die 240 and aligns with the stripping pad 250 through the pilot hole 5 made in the coil. At fourth stage, the blanked sheet moves further by pitch distance and the stripping pad 250 holds the panel on moving the upper die 240 downward and aligns with the guide. Now, a second blank B2 is cut by aligning upper and lower cutters 242 204 to exit from the roller conveyor to die side and to be stacked by the operator.

Figure 7 shows the perspective view of the stripper pad required in the automated blanking line 200 of Figure 5b for holding and pressurizing the metal sheet in the position during the blank cutting/blanking process. During blanking operation, the coil is held by pressure applied by stripper pad 250, which is guided in upper die 240 by means of guide pins 245 sliding against guide bush 252 fitted in the stripper pad 250. This stripper pad 250 maintains very close tolerances of 5-10 microns by means of guide pins 245 while operating in the upper die 240.
WORKING OF THE INVENTION

The present invention relates to a blanking die strip configured for an automated blanking line capable of producing two blanks /stroke. The method using the sheet metal blanks produced by this blanking die strip is applicable for producing sheet metal blanks both with and without scrap.

For producing blanks with scrap, the blanks are collected at the sides of the die, whereas for producing blanks without scrap, the scrap is cut at the last stage on conveyor of blanking process.

Accordingly, a sheet metal coil is fed into the die by a coil feeding unit. This coil is supported by a coil support system 220 and guided by coil guides 222, 224. It is assumed that coil feeding into the die is started from the first blank to be cut.

Stage I - Once the coil reaches a distance equals to end of stage I, the die makes a first stroke, in which the coil is held by pressure applied by means of the stripping pad 250. As the stroke of the stripper pad 250 is proceeded to completion, a pilot hole 214 is pierced through the coil by means of piercing punch 210 and die cavity 210. At the same time, upper die 240 enters into the coil to cut the blank by means of the lower steel cutter 204, which maintains a cutting clearance with respect to the upper steel cutter 242 just sufficient to produce burr-free blanks. The first blank B1 cut at this stage I moves through the roller conveyor 216 towards the die side and the sideway stacking of the first blank is done by the operator. On the upper die 240 moving upward, the pressure on the blanked metal sheet is removed and it moves forward by a pitch distance P.

Stage II - As the first blanked sheet moves further by pitch distance P ensured by locking the coil movement by a pilot punch 232 which moves downward with upper die 240 and aligns with pilot hole 214 pierced on the coil at stage I through the stripping pad 250.

Stage III - Coil is idle and no cutting occurs at this stage.
Stage IV - Sheet moves further with pitch distance P and as the upper die 240 moves downward and aligns with guide, the stripping pad 250 holds the panel by pressure and so by aligning the upper steel cutter 242 and lower die cutters 204, a second blank B2 is cut and exits the roller conveyor 218 to the die side and stacked by the operator. In the same stage, scraps 16, 17, 18, 19 are cut in the scrap cutter 2. This cut scrap S1, S2, S3, S4 are moved to the scrap conveyor 218 by means of scrap chutes 208 and 226. Since the coil is fed continuously and moved forward by pitch distance P, two blanks B1 and B2 are started to be cut by two cutting die cavities 204 and moved by the roller conveyors 216 and 218 respectively. Hence, for each die stroke, the coil progresses by pitch distance P and two blanks are produced thereby.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The automated blanking line with an improved die-strip layout for producing sheet metal blanks at high-speed and configured in accordance with the present invention has the following technical and economic advantages:

• Blanks are produced after by drop through and scrap is cut in the last stage.

• On automated blanking line, the nesting of the blank with scrap is possible and for producing the blanks with very high accuracy.

• The scrap cutting occurs only in the last stage of the die.

• Offers faster process to produce two blanks/stroke, on automated blanking line running at very high speeds of 25-30 SPM to increase blank production.

• No operator intervention is necessary for blanking operation on metal coil.

• Extra material leaves only at the end of the oversized coils.

• Single stage process ensures fine blank edge.

• Facilitates a highly accurate and consistent blank production.

• Significantly improved yield due to nested together blanks.

• Strip layout for body panel component production applicable for producing and nesting together blanks with scrap.

The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which this embodiment may be used and to further enable the skilled person in the relevant art to practice this invention. The description provided herein is purely by way of example and illustration.

Although, the embodiments presented in this disclosure have been described in terms of its preferred embodiments, the skilled person in the art would readily recognize that these embodiments can be applied with modifications possible within the spirit and scope of the present invention as described in this specification by making innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies and assemblies, in terms of their size, shapes, orientations and interrelationships without departing from the scope and spirit of this invention.

While considerable emphasis has been placed on the specific features of the preferred embodiment described here, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other changes in the preferred embodiment of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

Many of the fastening, connection, processes and other means and components utilized in this invention are widely known and used in the field of the invention described, and their exact nature or type is not necessary for an understanding and use of the invention by a person skilled in the art and they will not therefore be discussed in significant detail. The numerical values given of various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher or lower than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the disclosure unless there is a statement in the specification to the contrary.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.

The use of the expression “a”, “at least” or “at least one” shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.

Also, any reference herein to the terms ‘left’ or ‘right, ‘up’ or ‘down, or ‘top’ or ‘bottom’ are used as a matter of mere convenience, and are determined by standing at the rear of the machine facing in its normal direction of travel.

Furthermore, the various components shown or described herein for any specific application of this invention can be widely known or used in the art by persons skilled in the art and each will likewise not therefore be discussed in significant detail. When referring to the figures, like parts are numbered the same in all of the figures.