CN113399582A - Novel vertical combined steel drum middle section forming equipment - Google Patents

Novel vertical combined steel drum middle section forming equipment Download PDF

Info

Publication number
CN113399582A
CN113399582A CN202110638743.1A CN202110638743A CN113399582A CN 113399582 A CN113399582 A CN 113399582A CN 202110638743 A CN202110638743 A CN 202110638743A CN 113399582 A CN113399582 A CN 113399582A
Authority
CN
China
Prior art keywords
temporary storage
flanging
storage station
top end
framework
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202110638743.1A
Other languages
Chinese (zh)
Inventor
赵伟
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cpmc Investment Co ltd
Original Assignee
Cpmc Investment Co ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Cpmc Investment Co ltd filed Critical Cpmc Investment Co ltd
Priority to CN202110638743.1A priority Critical patent/CN113399582A/en
Publication of CN113399582A publication Critical patent/CN113399582A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21DWORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D51/00Making hollow objects
    • B21D51/16Making hollow objects characterised by the use of the objects
    • B21D51/18Making hollow objects characterised by the use of the objects vessels, e.g. tubs, vats, tanks, sinks, or the like

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Press Drives And Press Lines (AREA)

Abstract

The invention discloses novel vertical combined steel drum middle section forming equipment which comprises a lower framework, an upper framework, a temporary storage station before flanging, a flanging lifting mechanism and a temporary storage station before rib expansion, wherein the upper framework is arranged above the lower framework, the temporary storage station before flanging is arranged on one side of the top end of the lower framework, the flanging lifting mechanism is arranged at the top end of the lower framework on one side of the temporary storage station before flanging, the temporary storage station before rib expansion is arranged at the top end of the lower framework on one side of the temporary storage station before flanging, the rib expansion lifting mechanism is arranged at the top end of the lower framework on one side of the temporary storage station before rib expansion, a connecting rod synchronous conveying mechanism is arranged at the top end of the lower framework on one end of the rib expansion lifting mechanism, and a drum body synchronous moving motor is arranged at the top end of the lower framework on one side of the connecting rod synchronous conveying mechanism. The invention not only ensures the quality of the workpiece when the forming equipment is used, improves the practicability of the equipment, but also improves the convenience when the forming equipment is used.

Description

Novel vertical combined steel drum middle section forming equipment
Technical Field
The invention relates to the technical field of steel drum manufacturing in the metal packaging industry, in particular to novel vertical combined type steel drum middle section forming equipment.
Background
A steel drum with 50-250L capacity is made up of steel sheet through rolling it into drum, welding, flanging the upper and lower ends of drum, expanding ribs, shaping corrugations, necking, and sealing top and bottom covers.
In the manufacturing process of a steel barrel body, a barrel-shaped workpiece with two openings formed after a thin steel plate is rolled and welded needs to be flanged at the end opening of the barrel, then ribs are expanded from inside to outside on the barrel body to increase the strength, then a plurality of corrugated reinforcing ribs are formed on the barrel body, then the barrel opening is selectively necked, four processes are performed in total, and then the next process is performed.
The traditional equipment for processing the steel barrel body in the current market mainly comprises two processes: one is horizontal, the workpiece moves horizontally in the conveying and processing process, the other is vertical, the workpiece moves vertically in the conveying and processing process, the processing equipment of the two processes has different shapes, but each process of flanging, expanding rib, corrugation and necking is completed by one independent equipment, and each equipment is connected by a conveying belt. No matter the vertical and horizontal barrel-making process, the processing method is similar to that of the vertical and horizontal barrel-making process, and the barrel body is driven to rotate through the die and is rolled on the barrel body to form the reinforcing ribs and the corrugations.
The existing forming equipment on the market has various types, can basically meet the use requirements of people, but still has certain defects, and has the following specific problems.
(1) The barrel body of the existing forming equipment is easy to scratch due to relative friction between the barrel body and a die, and the quality is also easy to be affected by workpiece scratching due to the long conveying system and large occupied area between the working procedures;
(2) the existing molding equipment ensures that the production line needs more labor hours for normal operation and maintenance and the labor cost is high because each procedure is completed by a single independent device;
(3) the upper framework and the lower framework of the existing molding equipment are mostly of an integrated structure, so that the transportation and the disassembly and the assembly are inconvenient, and people are often troubled.
Disclosure of Invention
The invention aims to provide novel vertical combined type steel drum middle section forming equipment, which aims to solve the problems that the drum body is easy to scratch due to relative friction between the drum body and a mould of the forming equipment, the labor hour required by normal operation and maintenance is large, and the upper framework and the lower framework are mostly in an integrated structure in the background technology.
In order to achieve the purpose, the invention provides the following technical scheme: a novel vertical combined steel drum middle section forming device comprises a lower framework, an upper framework, a temporary storage station before flanging, a flanging lifting mechanism and a temporary storage station before rib expansion, wherein the upper framework is arranged above the lower framework, the temporary storage station before flanging is arranged on one side of the top end of the lower framework, the flanging lifting mechanism is arranged at the top end of the lower framework on one side of the temporary storage station before flanging, the rib expansion lifting mechanism is arranged at the top end of the lower framework on one side of the flanging lifting mechanism, which is far away from the temporary storage station before flanging, the rib expansion lifting mechanism is arranged at the top end of the lower framework on one side of the rib expansion lifting mechanism, a connecting rod synchronous conveying mechanism is arranged at the top end of the lower framework on one side of the connecting rod synchronous conveying mechanism, a drum body synchronous moving motor is arranged at the top end of the lower framework on one side of the connecting rod synchronous conveying mechanism, and a drum holding opening and closing motor is arranged on the outer wall of the connecting rod synchronous conveying mechanism on one side of the drum body synchronous moving motor, the bottom end of the bucket-holding opening and closing motor is connected with the top end of the lower framework.
Preferably, equidistant support columns are installed at the two ends of the top of the lower framework, and the top ends of the support columns are connected with the bottom end of the upper framework, so that the upper framework and the lower framework are disassembled and assembled.
Preferably, one side of the top end of the upper framework is provided with a flanging forming mechanism, and the top end of the upper framework on one side of the flanging forming mechanism is provided with a rib expanding forming mechanism, so that the barrel body can be subjected to flanging and rib expanding process treatment.
Preferably, the top end of the upper framework, on the side of the rib expansion forming mechanism far away from the flanging forming mechanism, is provided with a corrugation forming mechanism, and the top end of the upper framework, on the side of the corrugation forming mechanism far away from the rib expansion forming mechanism, is provided with a necking forming mechanism, so that the barrel body is subjected to corrugation and necking process treatment.
Preferably, the top end of the lower framework, away from one side of the temporary storage station before the rib expansion, of the rib expansion lifting mechanism is provided with a corrugated temporary storage station, and the top end of the lower framework, away from one side of the rib expansion lifting mechanism, of the temporary storage station before the corrugations is provided with a corrugated lifting mechanism, so that the barrel body is conveyed to the position of the corrugated forming mechanism to be subjected to corrugated forming process treatment.
Preferably, the lower framework top end of one side of the corrugated lifting mechanism away from the corrugated temporary storage station is provided with a temporary storage station before necking, and the lower framework top end of one side of the corrugated lifting mechanism away from the temporary storage station before necking is provided with a necking lifting mechanism, so that the barrel body is conveyed to the necking forming mechanism to be subjected to necking forming process treatment.
Compared with the prior art, the invention has the beneficial effects that: the novel vertical combined type steel drum middle section forming equipment not only ensures the quality of a workpiece when the forming equipment is used, improves the practicability of the equipment, but also improves the convenience when the forming equipment is used;
(1) by arranging the temporary storage station before flanging, the flanging lifting mechanism, the temporary storage station before rib expanding, the rib expanding lifting mechanism, the temporary storage station before corrugation, the corrugation lifting mechanism, the temporary storage station before necking and the necking lifting mechanism, the temporary storage station before flanging, the flanging lifting mechanism, the temporary storage station before rib expanding, the rib expanding lifting mechanism, the temporary storage station before corrugation, the corrugation lifting mechanism, the temporary storage station before necking and the necking lifting mechanism are sequentially arranged at the top end of the lower framework from right to left, so that the barrel is respectively temporarily stored and conveyed to the flanging forming mechanism, the rib expanding forming mechanism, the corrugation forming mechanism and the necking forming mechanism are positioned, the phenomena of long conveying system and large occupied area between the working procedures are avoided, the phenomenon of scratching of the outer wall of a workpiece can be avoided, and the quality of the workpiece when the forming equipment is used is ensured;
(2) by arranging the flanging forming mechanism, the rib expanding forming mechanism, the corrugation forming mechanism and the necking forming mechanism and adopting a brand-new production process form, the flanging forming mechanism, the rib expanding forming mechanism, the corrugation forming mechanism and the necking forming mechanism are sequentially arranged at the top end of the upper framework from right to left, so that the four processes of flanging, rib expanding, corrugation forming and necking are integrated on one device to be completed, the labor hour for scratching and daily operation and maintenance in the workpiece conveying process is reduced, the labor cost is further reduced, and the practicability of the device is improved;
(3) through being provided with down skeleton, last skeleton and support column, all adopt components of a whole that can function independently shaping processing through skeleton and last skeleton down to skeleton and last skeleton under the connection of a plurality of support columns, make former keep integrative complete, and then can be convenient for carry out dismouting and transportation processing to it, thereby the convenience when having improved the former use.
Drawings
FIG. 1 is a schematic illustration of an explosive structure according to the present invention;
FIG. 2 is an exploded view of the flanging forming mechanism of the present invention;
FIG. 3 is an exploded view of the expansion forming mechanism of the present invention;
FIG. 4 is an exploded view of the corrugating mechanism of the present invention;
FIG. 5 is an exploded view of the necking mechanism of the present invention.
In the figure: 1. a lower framework; 2. temporarily storing a station before necking; 3. a necking down elevating mechanism; 4. mounting a framework; 5. a flanging forming mechanism; 6. a necking formation mechanism; 7. a corrugation forming mechanism; 8. a rib expansion forming mechanism; 9. a rib-expanding lifting mechanism; 10. a support pillar; 11. temporarily storing a station before flanging; 12. a flanging lifting mechanism; 13. a barrel body synchronous moving motor; 14. temporarily storing a station before the rib is expanded; 15. a connecting rod synchronous conveying mechanism; 16. a motor for opening and closing the bucket; 17. temporarily storing a station before corrugation; 18. ripple elevating system.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1-5, an embodiment of the present invention is shown: a novel vertical combined type steel drum middle section forming device comprises a lower framework 1, an upper framework 4, a temporary storage station 11 before flanging, a flanging lifting mechanism 12 and a temporary storage station 14 before rib expanding, wherein the upper framework 4 is arranged above the lower framework 1, supporting columns 10 with equal intervals are arranged at two ends of the top of the lower framework 1, and the top ends of the supporting columns 10 are connected with the bottom end of the upper framework 4 so as to assemble and disassemble the upper framework 4 and the lower framework 1;
a flanging forming mechanism 5 is arranged at one side of the top end of the upper framework 4, and a rib expanding forming mechanism 8 is arranged at the top end of the upper framework 4 at one side of the flanging forming mechanism 5 so as to carry out flanging and rib expanding process treatment on the barrel body;
the top end of the upper framework 4 on one side of the rib expansion forming mechanism 8, which is far away from the flanging forming mechanism 5, is provided with a ripple forming mechanism 7, and the top end of the upper framework 4 on one side of the ripple forming mechanism 7, which is far away from the rib expansion forming mechanism 8, is provided with a necking forming mechanism 6, so that the barrel body is subjected to ripple and necking process treatment;
a flanging front temporary storage station 11 is arranged on one side of the top end of the lower framework 1, a flanging lifting mechanism 12 is arranged on the top end of the lower framework 1 on one side of the flanging front temporary storage station 11, a rib expansion front temporary storage station 14 is arranged on the top end of the lower framework 1 on one side, away from the flanging front temporary storage station 11, of the flanging lifting mechanism 12, a rib expansion lifting mechanism 9 is arranged on the top end of the lower framework 1 on one side, away from the rib expansion front temporary storage station 14, of the rib expansion front temporary storage station 14, a ripple front temporary storage station 17 is arranged on the top end of the lower framework 1 on one side, away from the rib expansion lifting mechanism 9, of the ripple front temporary storage station 17, and therefore the barrel body is conveyed to the position 7 of the ripple forming mechanism to be subjected to ripple forming process;
a necking front temporary storage station 2 is arranged at the top end of the lower framework 1 on the side, away from the corrugation front temporary storage station 17, of the corrugation lifting mechanism 18, and a necking lifting mechanism 3 is arranged at the top end of the lower framework 1 on the side, away from the corrugation lifting mechanism 18, of the necking front temporary storage station 2, so that the barrel body can be conveyed to the position of the necking forming mechanism 6 to be subjected to necking forming process treatment;
and the top of the lower framework 1 at one end of the tendon-expanding lifting mechanism 9 is provided with a connecting rod synchronous conveying mechanism 15, the top of the lower framework 1 at one side of the connecting rod synchronous conveying mechanism 15 is provided with a barrel body synchronous moving motor 13, the outer wall of the connecting rod synchronous conveying mechanism 15 at one side of the barrel body synchronous moving motor 13 is provided with a barrel holding opening and closing motor 16, and the bottom end of the barrel holding opening and closing motor 16 is connected with the top end of the lower framework 1.
The working principle is as follows: when the forming equipment is used, firstly, the connecting rod synchronous conveying mechanism 15 is arranged at the top end of the lower framework 1, and is driven by the barrel body synchronous moving motor 13 and the barrel holding opening and closing motor 16, because the top of the lower framework 1 is provided with eight stations, wherein four stations are the positions of the flanging lifting mechanism 12, the rib expanding lifting mechanism 9, the ripple lifting mechanism 18 and the necking lifting mechanism 3, the barrel body can be lifted to the height of a processing mold, the other four stations are the temporary storage station 11 before flanging, the temporary storage station 14 before rib expanding, the temporary storage station 17 before ripple and the temporary storage station 2 before necking, which are temporary storage stations designed for ensuring synchronous continuous processing, when the equipment is operated, the connecting rod synchronous conveying mechanism 15 repeatedly feeds the barrel body in a uniform reciprocating motion, simultaneously holds eight barrels to move forward one station when the equipment moves forward, releases the holding of all the barrels to move backward one station when the equipment moves backward, the barrel body to be processed is gradually conveyed to the next station, the barrel body is conveyed out of the combined forming machine to enter a conveyer belt after processing, the concrete process mode is that the barrel body which is well rolled and welded is conveyed to a temporary storage station at the inlet of the combined machine, the barrel body is sequentially conveyed to a temporary storage station 11 before flanging by a connecting rod synchronous conveying mechanism 15, a flanging lifting mechanism 12 enables the barrel body to be lifted to abut against an upper flanging die of a flanging forming mechanism 5, the upper end opening and the lower end opening of the barrel body complete flanging under the action of a jacking force, the flanged barrel body is continuously conveyed to a temporary storage station 14 before a rib expanding by the connecting rod synchronous conveying mechanism 15, a rib expanding lifting mechanism 9 lifts the flanged barrel body to a position between an inner rib expanding die and an outer rib expanding die of a rib forming mechanism 8, the inner die and the outer rib expanding die act to form a barrel body reinforcing rib, reinforcing ribs at different positions can be temporarily stored for a plurality of times by the barrel body according to requirements, the barrel body after rib expanding is continuously conveyed to a corrugated front station 17 by the connecting rod synchronous conveying mechanism 15, the ripple elevating system 18 lifts the barrel after the rib expansion to the position between the ripple inner and outer dies of the ripple forming mechanism 7, the ripple inner and outer dies act to complete the ripple forming of the barrel, the barrel can form ripples at different positions from top to bottom for many times as required, the barrel after the ripple is completed is continuously conveyed to the temporary storage station 2 before necking by the connecting rod synchronous conveying mechanism 15, the necking elevating system 3 lifts the barrel to the position between the necking inner and outer dies of the necking forming mechanism 6, the necking inner and outer dies act to enable the upper barrel opening to be pressed laterally to complete the necking forming, and finally the barrel after being processed is conveyed out of the combiner by the connecting rod synchronous conveying mechanism 15, so that the use of the forming equipment is completed.

Claims (6)

1. A novel vertical combined steel drum middle section forming device is characterized by comprising a lower framework (1), an upper framework (4), a temporary storage station (11) before flanging, a flanging lifting mechanism (12) and a temporary storage station (14) before rib expansion, wherein the upper framework (4) is arranged above the lower framework (1), the temporary storage station (11) before flanging is arranged on one side of the top end of the lower framework (1), the flanging lifting mechanism (12) is arranged on the top end of the lower framework (1) on one side of the temporary storage station (11) before flanging, the temporary storage station (14) before rib expansion is arranged on the top end of the lower framework (1) on one side of the flanging lifting mechanism (12) far away from the temporary storage station (11) before flanging of the flanging lifting mechanism (12), the rib expansion lifting mechanism (9) is arranged on the top end of the lower framework (1) on one side of the rib expansion lifting mechanism (9), and a connecting rod synchronous conveying mechanism (15) is arranged on the top of the lower framework (1), barrel body synchronous motion motor (13) is installed at lower skeleton (1) top of connecting rod synchronous motion mechanism (15) one side, and installs on connecting rod synchronous motion mechanism (15) outer wall of barrel body synchronous motion motor (13) one side and embraces bucket motor (16) that opens and shuts, embraces the bottom of bucket motor (16) that opens and shuts and is connected with the top of lower skeleton (1).
2. The novel vertical combined type steel drum middle section forming equipment as claimed in claim 1, is characterized in that: support columns (10) with equal intervals are installed at two ends of the top of the lower framework (1), and the top ends of the support columns (10) are connected with the bottom end of the upper framework (4).
3. The novel vertical combined type steel drum middle section forming equipment as claimed in claim 1, is characterized in that: and one side of the top end of the upper framework (4) is provided with a flanging forming mechanism (5), and the top end of the upper framework (4) on one side of the flanging forming mechanism (5) is provided with an expansion rib forming mechanism (8).
4. The novel vertical combined type steel drum middle section forming equipment as claimed in claim 3, wherein: and a ripple forming mechanism (7) is arranged at the top end of the upper framework (4) on one side of the rib expansion forming mechanism (8) far away from the flanging forming mechanism (5), and a necking forming mechanism (6) is arranged at the top end of the upper framework (4) on one side of the ripple forming mechanism (7) far away from the rib expansion forming mechanism (8).
5. The novel vertical combined type steel drum middle section forming equipment as claimed in claim 1, is characterized in that: the top end of the lower framework (1) on one side, away from the rib expansion front temporary storage station (14), of the rib expansion lifting mechanism (9) is provided with a ripple front temporary storage station (17), and the top end of the lower framework (1) on one side, away from the rib expansion lifting mechanism (9), of the ripple front temporary storage station (17) is provided with a ripple lifting mechanism (18).
6. The novel vertical combined type steel drum middle section forming equipment as claimed in claim 5, wherein: ripple elevating system (18) keep away from lower skeleton (1) top of ripple preceding temporary storage station (17) one side and be equipped with before the necking temporary storage station (2), and just temporary storage station (2) keep away from lower skeleton (1) top of ripple elevating system (18) one side before the necking is equipped with necking down elevating system (3).
CN202110638743.1A 2021-06-08 2021-06-08 Novel vertical combined steel drum middle section forming equipment Pending CN113399582A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110638743.1A CN113399582A (en) 2021-06-08 2021-06-08 Novel vertical combined steel drum middle section forming equipment

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110638743.1A CN113399582A (en) 2021-06-08 2021-06-08 Novel vertical combined steel drum middle section forming equipment

Publications (1)

Publication Number Publication Date
CN113399582A true CN113399582A (en) 2021-09-17

Family

ID=77677230

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110638743.1A Pending CN113399582A (en) 2021-06-08 2021-06-08 Novel vertical combined steel drum middle section forming equipment

Country Status (1)

Country Link
CN (1) CN113399582A (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3797429A (en) * 1973-02-22 1974-03-19 United Can Co Method and apparatus for necking and flanging can bodies
CN2130619Y (en) * 1992-07-21 1993-04-28 西安市机械研究所 Shaper for metallic cylinder body
CN202804005U (en) * 2012-09-28 2013-03-20 张立君 Necking bucket integrated machine
CN111482509A (en) * 2020-03-26 2020-08-04 南阳浩帆车辆部件有限公司 Machining system and machining method of dragging seat assembly
CN111745073A (en) * 2020-05-18 2020-10-09 广州中粮制桶有限公司 Barrel frame forming combination machine

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3797429A (en) * 1973-02-22 1974-03-19 United Can Co Method and apparatus for necking and flanging can bodies
CN2130619Y (en) * 1992-07-21 1993-04-28 西安市机械研究所 Shaper for metallic cylinder body
CN202804005U (en) * 2012-09-28 2013-03-20 张立君 Necking bucket integrated machine
CN111482509A (en) * 2020-03-26 2020-08-04 南阳浩帆车辆部件有限公司 Machining system and machining method of dragging seat assembly
CN111745073A (en) * 2020-05-18 2020-10-09 广州中粮制桶有限公司 Barrel frame forming combination machine

Similar Documents

Publication Publication Date Title
CN1654162A (en) Automatic manufacturing technique of large sized steel pipe
CN112045087A (en) Rib mechanism and system jar production line that rises of adjustable muscle line
CN201304445Y (en) Die for producing aluminum shell blank of capacitor with coiled material
CN113399582A (en) Novel vertical combined steel drum middle section forming equipment
CN111745073B (en) Barrel frame forming combination machine
CN112091110A (en) Steel pail system jar production line
CN204735576U (en) Flange flanger
CN108326145B (en) Composite stamping forming die for hinge piece
CN104148455A (en) Swing-up forming manufacturing system for heavy steel plate silo
CN210998485U (en) Rubber ring sleeving machine for producing automobile valve sleeves
CN210412123U (en) Deformed steel clamping, overturning, pushing and punching mechanism
CN206951960U (en) The automobile back door upper hinge reinforcing plate progressive die
CN107716623B (en) Steel pipe shaping press
CN112355140A (en) Novel multi-station flaring progressive die and stamping method for stainless steel round pipe
CN2130619Y (en) Shaper for metallic cylinder body
CN112045017A (en) Corrugated steel plate manufacturing method
CN218873344U (en) Rim rounding device
CN204974989U (en) A hot briquetting mould structure for seamless elbow
CN110961508A (en) Rim one shot forming roll forming machine
CN104858280A (en) Flange flanging machine
CN216324525U (en) Progressive die process structure of automobile air compressor gasket
CN218192181U (en) Local shaping equipment for large steel pipe
CN218252444U (en) Multi-station special-shaped can expanding machine
CN220216374U (en) Stamping processing die for oil tank door cover
CN219817731U (en) Tunnel annular wall protection steel plate forming device

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
RJ01 Rejection of invention patent application after publication

Application publication date: 20210917

RJ01 Rejection of invention patent application after publication