DESC:FIELD OF INVENTION

The present invention relates to sheet metal die operations. In particular, the present invention relates to eliminating the stamping of flakes / metal chips on the component during trimming operation of die. More particularly, the present invention relates to providing a safe environment for machine operator.

BACKGROUND OF THE INVENTION

In modern automotive manufacturing processes, sheet metal is widely used for making various sheet metal components on press machine by means of dies for shaping desired profiles and/or shapes of these pressed components.

The first operation uses a draw die for forming the basic shape of the component. The next operation uses a trimming die, in which the excess sheet metal is trimmed as per requirement. This trimming die mainly consists of three parts, i.e. cavity, punch and panel holder (PAD). During this trimming operation, the sheet metal panel is held between PAD and cavity and then pressed against the cutters by applying force of the press machine. For the subsequent cutting operation, the cutting die includes a primary die cutter and a secondary die cutter. This cutting operation takes place continuously and sheet metal is cut with die-cutters and small metal chips are generated at the cutting edges. These small metal chips create marks on sheet metal panel which are considered as defects in all automated press shops. Therefore, the die cutters must be frequently sharpened to avoid these marks.

DISADVANTAGES WITH THE PRIOR ART

However, there are many disadvantages associated with the conventional methods of manufacturing sheet metal components for automotive industries. These disadvantages are briefly discussed below:
During sheet metal cutting operations, metal is cut against the metal cutters and metal shearing takes place. This continuous shearing operation generates small fine metal chips, which get deposited at the edges of die cutters. Particularly on automated lines, when the parts are unloaded by robots / cross bar mechanisms / automated pick and place mechanisms, a vacuum is created between the sheet metal panel surface and the die surface for sucking air from the outer area.

The continuously working die-cutter deteriorates at very fine edge/s and generate flake/s or scrap piece/s. When the air is blown from the bottom of sheet metal component under process, it gets filled in the available space between the component and the lower die surface. Here, the moving-in air carries flakes or small metal chips therewith, which fall on the punch / die surfaces and stay there. When the next sheet metal panel is loaded on the punch / die surface, the flakes are trapped between the new panel and the die surface and on stamping further, create a mark on panel, which requires reworking before the painting process of the sheet metal component so formed, because the component’s appearance is hampered due to these marks.

This reworking of the component leads to cost increase and also reduces the press line efficiency. This occurs because, any such flakes should be removed by the checking personnel and the whole press operation must be put on hold until removing these flakes. Accordingly, on detecting flakes, the press line is stopped, and the operator needs to go to the place where he observes these marks being generated, then cleans the flakes from the die surface and restarts the press line in auto mode.

Any entry in the press line with the die kept in a clamped condition and motor still running, would compromise the safety of sheet metal component’s pressing operation as this poses a slipping hazard for the personnel and also the risk of injury due to the mishandling of components.

Further, the profile of different component is different, e.g. some components are configured flat and the others may have drawing depth of above 200 mm and thus, heavy cams need to be used for cutting the parts.

However, the length of sheet metal panel cutting edges normally ranges from 2-16 m and due to impact load on press machines and also because of vibrations at each stroke of press machine, maintaining the sharpness of the complex shaped cutters always poses challenges.

Moreover, the thickness and material grade of different component is also different, so these widely differing cutting requirements make it very difficult to maintain the clearances and requires highly skilled manpower. The manufacturing process consumes substantial time and resources for maintaining the sharpness of the cutting edges.

However, since cutters cut the components at high speeds with substantial vibrations due to impact loads and several cams are used in dies for cutting profiled components, wherein maintaining the clearance is a big challenge because of cams having many interfacing parts. The accuracy of press machine also plays an important role to precisely maintain these die clearances.

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 a low-cost system for making spotless pressed sheet metal components, which can be universally deployed.

Another object of the present invention is to provide a system for making spotless pressed sheet metal components, which is simple to manufacture and operate.
Still another object of the present invention is to provide an effective system for eliminating surface defects in sheet metal components while being made on press machines by press-forming operation.

Yet another object of the present invention is to provide a high-productivity system for making pressed sheet metal components

A further object of the present invention is to provide a safe and secure system for making spotless pressed sheet metal components.

Still further object of the present invention is to provide a system for making spotless pressed sheet metal components, which reduces press machine down-time to a minimum.

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 system for removing flakes or scrap pieces from dies during pressing of sheet metal components, said system comprising:

• an upper die assembly equipped with an upper tool and on the press-slide fitted on press crown and movable by means of an electric motor;

• a lower die assembly equipped with a lower tool;

• scrap chutes for removing flakes/scrap pieces generated during metal cutting/trimming operations;

• a bolster plate fitted over a plurality of cushion pin plates supported on the sheet metal press bed; said cushion pin plates vertically movable by means of a cushion unit assembly; and
• a sheet metal panel to be cut/trimmed between said upper and lower die assemblies for making a targeted sheet metal component;

wherein an air blowing system is configured between said upper die portion and said lower die portion to blow air in a predefined pattern on the bottom face of said sheet metal panel supplied from a compressed air source.

Typically, the upper die assembly comprises: an upper tool having a pierce punch fitted between a pad holding and said upper press-slide and provided with springs on both sides thereof; said pad holding fitted with a plurality of upper scrap cutters thereon.

Typically, the lower die assembly comprises: a lower tool fitted with a punch and die button, and scrap chutes provided on either side thereof for removing scrap/flakes therethrough.

Typically, the air blowing system comprises a plurality of nozzles each connected via respective pneumatic pipe to a compressed air source.

Typically, the plurality of pneumatic pipes is connected to a common pneumatic pipe supplying compressed air from said compressed air source, such as an air compressor.

Typically, the plurality of nozzles comprises a predetermined number of nozzles, which are selected depending on the complexity of said sheet metal component.

Typically, the tips of the nozzles are disposed at different locations on the upper surface of said punch, said locations are selected depending on the targeted coverage area for blowing the flakes/scrap pieces away from said sheet metal component.

Typically, the nozzles are disposed to cover a coverage area of 900 to 1200 thereabout.
Typically, the nozzles are disposed such that said coverage area of each nozzle overlaps about 10% of the coverage area of the adjoining nozzle/s thereof.

Typically, the air supply to said nozzles is stopped as soon as said press slide reaches the topmost position thereof.

DESCRIPTION OF THE INVENTION

In order to overcome the aforesaid issues, in accordance with the present invention, an air blowing system is provided from bottom of the sheet metal panel through nozzles connected via pneumatic pipes. This air-blowing system is integrated in the sheet metal dies of the press machine used for making pressed sheet metal components.

It further includes a plurality of nozzles to blow air between the lower die and pressed sheet metal component being manufactured. The position of these nozzles can be determined depending on the complexity of the sheet metal component to be made and the area requiring coverage by blowing the flakes off therefrom. The nozzle point should cover 90-1200 angle and each nozzle position should be configured such that it overlaps 10% of area covered by the other (adjoining) nozzles.

Moreover, the number of nozzles is decided on basis of the size and complexity of the component to be made. The cam-operated cutting areas require the most air coverage and the vertical cutting areas require the least air coverage.

The nozzle points, direction/position, air pressure requirements can be varied with the size and complexity of the components to be made.

Since, air acquires the shape of any container filled therewith and leaks therefrom even if a very fine gap exists therein. This completely prevents the entry of flakes/scrap pieces in the cavity formed between the sheet metal panel and lower die to eliminate any marks being made on the pressed, trimmed/cut sheet metal component, as was prevalent in the conventional cutting/trimming die application in sheet metal presses.

The air filled in this space during cutting/trimming operation escapes from the gap between the aforesaid fine edge/s generating flakes and carries the flake/s away from the dies to prevent from getting stamped therebetween, which would otherwise have made undesirable marks on the sheet metal components, thus manufactured.

Moreover, after cutting the pressed component from the sheet metal panel, it becomes light in weight and is slightly lifted to allow this air to escape from the periphery of the component surface to carry these flakes further away.

Once the unloader unloads the sheet metal panel, no vacuum is generated at the bottom of the component, because air is supplied from the bottom of the sheet metal panel, the outside air is not sucked in, so no venturi effect is created. Thus, any flakes remaining near the die cutting edge do not get carried inside the punch.

It is a simple and effective way to blow away the flakes generated from the damaged edges. Because air escapes from the gap between the sheet metal panel edge/s and damaged edge/s of the die-cutters, it carries the flakes lying at the edge.

Whatever is the shape of die and the component, due to its natural tendency, air occupies the shape of container and escapes from the finest gap in the compressed condition, which is damaged edge of the cutter here.

Also, the major concern of flakes flying in on the die surface when the component is unloaded due to vacuum effect is attended to. Since air is blown from the bottom of the sheet metal panel, the vacuum effect is not generated and the flakes flying on punch surface is eliminated.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

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

Figure 1a shows a conventional sheet metal press machine for making the components of diverse profiles/section/sheet metal thickness by using suitable dies and punches.

Figure 1b shows a schematic sheet metal panel holding attachment used in the press machine of Figure 1a.

Figure 2a shows the schematic arrangement of the trimming/cutting mechanism in the conventional press machine of Figure 1a, depicting the first stage of trimmed flakes/scrap pieces getting sucked between the panel and die surface due to vacuum created therebetween.

Figure 2b shows another view of the arrangement of Figure 2a depicting the trimmed flakes/scrap pieces getting stamped between the panel and the die surface to produce marks, which are considered disadvantageous for the components made thereby.

Figure 3a shows the schematic arrangement of the sheet metal press machine equipped with the system configured in accordance with the present invention for making spotless pressed sheet metal components, whereby trimmed flakes/scrap pieces are pushed out of the cavity formed between the formed sheet metal component and die surface due to air blown inside the cavity.

Figure 3b shows a detailed view in the region of the cavity and cutters with air blowing mechanism depicted in Figure 3a.

Figure 3c shows another detailed view of the air blowing mechanism of Figure 3a.
DETALED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following, the sheet metal press machine equipped with the system configured in accordance with the present invention for making spotless pressed sheet metal components 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 1a shows a conventional sheet metal press machine 10 for making the components of diverse profiles/section/sheet metal thickness by using suitable dies and punches. It includes a press crown and motor 12 fitted at the top thereof. A press-slide 14 and pad holding 16 fitted in upper tool 22 thereunder. A plurality of springs 18 are fitted between the upper tool 22 and the upper scrap cutters 24 on either side thereof. A pierce punch 32 is also provided between the pad holding 16 and upper tool 22. In the lower portion of the press machine 10, a pressed (profiled) sheet metal panel 50 is shown in thick dashed line. The scrap cutters 26 are fitted on either side of the lower tool 28. The scrap cutters or trimmers 26 trim the panel 50 in the scrap area 20 to generate many scrap pieces or flakes 36, which drop down in the scrap chute 30. This lower portion components are fitted on the press bed 40 by means of the bolster plate 42 and cushion pin plate 44.

Figure 1b shows a schematic arrangement of the attachment 60 used in the press machine of Figure 1a for holding the sheet metal panel 50.

Figure 2a shows the schematic arrangement of the trimming/cutting mechanism in the conventional press machine 10 of Figure 1a, which depicts the first stage of trimmed flakes/scrap pieces 36 generated by the trimming action of the trim cutters 24 on the lower die 35. These flakes 36 get sucked (marked as flakes 38 in the direction of bold arrows). The flakes 38 fly in on the punch due to a venturi effect and thereby reach between the panel 50 and upper surface of die 25 because of the vacuum created therebetween.

Figure 2b shows another view of the arrangement of Figure 2a depicting the upper trim cutters 24 fitted on the upper die 25. On pressing down the upper die on sheet metal panel 50, the upper trim cutters 24 trim the panel to produce flakes/scrap pieces 36 which are sucked between the panel 50 and the upper surface of the lower die/punch 35 and get stamped therebetween. These stamped flakes/scrap pieces 38 produce marks 70 on the panel 50, which are considered disadvantageous for the quality of sheet metal components thus manufactured.

Figure 3a shows the schematic arrangement of the sheet metal press machine 100 equipped with the system configured in accordance with the present invention for making spotless pressed sheet metal components, wherein trimmed flakes/scrap pieces are pushed out of the cavity formed between the formed sheet metal component and die surface due to air blown inside the cavity. The sheet metal press machine 100 includes a press crown and motor 112 fitted at the top thereof. A press-slide 114 and an upper tool 122 fitted thereunder. A lower tool 128 carries a profiled punch 132 for shaping the desired profile of the component to be made in the sheet metal panel 150. This punch 132 is provided with a plurality of air outlet nozzles 182 connected to an air supply 180 via a respective pneumatic/air pipe 184. In the lower portion of the press machine 100, the press bed 140 carries the bolster plate 142 and cushion pin plate 144, which in turn are supported on a cushion unit which includes a cushion piston and cylinder arrangement 190. This cushion unit 200 is operated to raise or lower the lower die assembly for producing the pressed sheet metal components.

Figure 3b shows a detailed enlarged view of the scrap cutters 124 on the die surface 126 in scrap area 120 provided with an air blowing mechanism 182, 184 depicted in Figure 3a.

Figure 3c shows another detailed view of the air blowing mechanism of Figure 3a. Here, a plurality of scrap cutters 124 are provided on the die surface 126 which is provided with die pockets 192.
The air blowing mechanism includes air blow 194 issued by means of air outlet nozzles 184 connected to air pipes 182. The nozzles 184 produce air blow 194 spread at an angle of 1200 thereabout. The air spreading zone of the adjoining nozzles 184 overlap to a certain extent to completely cover the scrap generation area 120 to ensure complete blowing of the flakes/scrap pieces 136 produced therein.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The system proposed in accordance with the present invention offers the following technical and economic advantages:

• Simple, cost effective mechanism with tremendous potential for its horizontal deployment across various press shops.

• Mostly eliminates loose flakes stamping problem from trimming die.

• Low-cost and very effective mechanism reducing rework and frequent line stoppage on noticing flake marks on the panel, thus increasing press line efficiency and reducing COPQ (cost of poor quality).

• Enhanced productivity because of die down-time reduction by 1%, the cost saving in critical and common facility of press shop is about Rs. 17 lakhs.

• Generates an additional capacity of about 22000 press-strokes.

• Eliminates unsafe condition for machine operators.

It is to be understood that the present invention is not limited in its application to the details of the construction and to the arrangements of the components as mentioned in the above description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, the terminologies used herein are for the purpose of description and should not be regarded as limiting.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept.

Therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. 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.

The description provided herein is purely by way of example and illustration. The various features and advantageous details are explained with reference to this non-limiting embodiment in the above description in accordance with the present invention.

The descriptions of well-known components and manufacturing and processing techniques are consciously omitted in this specification, so as not to unnecessarily obscure the specification. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Therefore, while the embodiments herein have been described in terms of preferred embodiments, the skilled person will recognize that the embodiments herein can be practiced with modification within the spirit and scope of embodiments described herein.

The skilled person can easily make innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies, assemblies and in terms of the size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.

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. ,CLAIMS:We claim:

1. A system for removing flakes or scrap pieces from dies during pressing of sheet metal components, said system comprising:

• an upper die assembly equipped with an upper tool and on the press-slide fitted on press crown and movable by means of an electric motor; and

• a lower die assembly equipped with a lower tool;

• scrap chutes for removing flakes/scrap pieces generated during metal cutting/trimming operations;

• a bolster plate fitted over a plurality of cushion pin plates supported on the sheet metal press bed; said cushion pin plates vertically movable by means of a cushion unit assembly; and

• a sheet metal panel to be cut/trimmed between said upper and lower die assemblies for making a targeted sheet metal component;

wherein an air blowing system is configured between said upper die portion and said lower die portion to blow air in a predefined pattern, on the bottom face of said sheet metal panel, supplied from a compressed air source.

2. System as claimed in claim 1, wherein said upper die assembly comprises: an upper tool having a pierce punch fitted between a pad holding and said upper press-slide and provided with springs on both sides thereof; said pad holding fitted with a plurality of upper scrap cutters thereon.

3. System as claimed in claim 1, wherein said lower die assembly comprises: a lower tool fitted with a punch and die button, and scrap chutes provided on either side thereof for removing scrap/flakes therethrough.

4. System as claimed in claim 1, wherein said air blowing system comprises a plurality of nozzles, each connected via a respective pneumatic pipe to a compressed air source.
5. System as claimed in claim 4, wherein said plurality of pneumatic pipes are connected to a common pneumatic pipe which supplies compressed air from said compressed air source, such as an air compressor.

6. System as claimed in claim 4, wherein said plurality of nozzles comprises a predetermined number of nozzles, which is selected depending on the complexity of said sheet metal component.

7. System as claimed in claim 4, wherein the tips of said nozzles are disposed at different locations on the upper surface of said punch, said locations are selected depending on the targeted coverage area for blowing the flakes/scrap pieces away from said sheet metal component.

8. System as claimed in claim 7, wherein said nozzles are disposed to cover a coverage area of 900 to 1200 thereabout.

9. System as claimed in claim 8, wherein said nozzles are disposed such that said coverage area of each nozzle overlaps about 10% of the coverage area of the adjoining nozzle/s thereof.

10. System as claimed in claim 9, wherein the air supply to said nozzles is stopped as soon as said press slide reaches the topmost position thereof.

Digitally Signed.

Dated: this day of 25th January 2018. (SANJAY KESHARWANI)
APPLICANT’S PATENT AGENT