CN109501060A - For making the method and mold of unmanned aerial vehicle body shell - Google Patents

For making the method and mold of unmanned aerial vehicle body shell Download PDF

Info

Publication number
CN109501060A
CN109501060A CN201811493344.5A CN201811493344A CN109501060A CN 109501060 A CN109501060 A CN 109501060A CN 201811493344 A CN201811493344 A CN 201811493344A CN 109501060 A CN109501060 A CN 109501060A
Authority
CN
China
Prior art keywords
die holder
mold
vehicle body
aerial vehicle
unmanned aerial
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.)
Granted
Application number
CN201811493344.5A
Other languages
Chinese (zh)
Other versions
CN109501060B (en
Inventor
孙康文
孙谋
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.)
Beihang University
Original Assignee
Beihang University
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 Beihang University filed Critical Beihang University
Priority to CN201811493344.5A priority Critical patent/CN109501060B/en
Publication of CN109501060A publication Critical patent/CN109501060A/en
Application granted granted Critical
Publication of CN109501060B publication Critical patent/CN109501060B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C33/00Moulds or cores; Details thereof or accessories therefor
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C33/00Moulds or cores; Details thereof or accessories therefor
    • B29C33/70Maintenance
    • B29C33/72Cleaning
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/28Shaping operations therefor
    • B29C70/30Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
    • B29C70/34Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation
    • B29C70/342Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation using isostatic pressure
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29LINDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00Other particular articles
    • B29L2031/30Vehicles, e.g. ships or aircraft, or body parts thereof
    • B29L2031/3076Aircrafts
    • B29L2031/3082Fuselages

Abstract

The invention belongs to air vehicle technique fields, more particularly to a kind of for making the method and mold of unmanned aerial vehicle body shell.1) method is the following steps are included: designing and processing the mold for making unmanned aerial vehicle body shell, mold includes upper die holder, lower die holder and internal model, internal model is used for the laying of shell laminated material, when upper die holder is connect with lower die holder, upper die holder and lower die holder carry out the type chamber of dimension shape when being encircled into for solidifying to shell laminated material;2) raw material of unmanned aerial vehicle body shell are surround to laying in internal model, stay certain interval distance in intermediate region in the die transition area laying of internal model, to guarantee the unmanned aerial vehicle body shell produced as front shell and aft case and not contact each other;3) internal model is placed in the type chamber that upper die holder and lower die holder surround, and upper die holder and lower die holder is fixedly connected;4) mold is integrally put into curing molding autoclave to be heating and curing, obtains the front shell and aft case of unmanned aerial vehicle body shell.

Description

For making the method and mold of unmanned aerial vehicle body shell
Technical field
The invention belongs to air vehicle technique field, more particularly to a kind of method for making unmanned aerial vehicle body shell and Mold.
Background technique
With the further development of technical field of aerospace, unmanned plane has become the emphasis of various countries' research.This kind of aircraft by In small in size, unmanned, the flight time is long, high-precision the features such as, it can be used for border district communication relay, monitoring, investigation monitoring Etc. various fields, have wide dual-use application prospect.Currently, grinding for Conventional compact grade unmanned aerial vehicle body shell System is generally used covering bonding, the clinching method of fitting fuselage framework ontology, generally can not through the casing that the method is developed Guarantee good aerodynamic characteristic and aesthetics, will increase the flight resistance of unmanned plane, to influence flight endurance, and then restricts this The application range of class unmanned plane.Therefore, it is necessary to the production method for improving unmanned aerial vehicle body shell, to better ensure that casing Aerodynamic characteristic.
Summary of the invention
The purpose of the present invention is at least solving one of above-mentioned problems of the prior art, which is by following skill What art scheme was realized:
The invention proposes a kind of methods for making unmanned aerial vehicle body shell, comprising the following steps:
1) mold for making unmanned aerial vehicle body shell is designed and processes, the mold includes upper die holder, lower die holder And internal model, internal model are used for the laying of shell laminated material, are removably connected between upper die holder and lower die holder, upper die holder and lower die When seat connection, upper die holder and lower die holder carry out the type chamber of dimension shape when being encircled into for solidifying to shell laminated material;Upper die holder, under Die transition area is equipped on mold and internal model, die transition area is that corresponding mold carries out at fuselage profile maximum secting area Congruence expands long and is formed;
2) raw material of unmanned aerial vehicle body shell are surround to laying in internal model, wherein spread in the die transition area of internal model Certain interval distance is stayed in intermediate region when layer, to guarantee the unmanned aerial vehicle body shell produced as front shell and aft case And it does not contact each other;
3) internal model is placed in the type chamber that upper die holder and lower die holder surround, and company is fixed in upper die holder and lower die holder It connects;
4) mold is integrally put into curing molding autoclave to be heating and curing, thus before obtaining unmanned aerial vehicle body shell Portion's shell and aft case.
Further, the method also includes following steps:
5) flash and sharp parts of front shell and aft case are removed;
6) shell connecting hole is processed in front shell and aft case;
7) cleaning treatment is carried out with surface of the alcohol to front shell and aft case.
Further, the length in the die transition area is 20mm.
Further, in the step 2) in the die transition area laying of internal model, in the clearance distance that intermediate region is stayed For 10mm.
Further, when mold being put into curing molding autoclave in the step 4) and being heating and curing, heating temperature It is 135 DEG C, heating-up time control was at 45 minutes, and in 1.1 standard atmospheric pressures, heating time is 2 hours for pressure control.
The invention also provides a kind of for making the mold of unmanned aerial vehicle body shell, including upper die holder, lower die holder and interior Mould, the internal model are used for the laying of shell laminated material, are removably connected between the upper die holder and lower die holder, the upper mold When seat is connect with the lower die holder, the upper die holder and lower die holder carry out dimension shape when being encircled into for solidifying to shell laminated material Type chamber.
Further, the upper die holder, lower die holder and internal model are manufactured in conjunction with mold public according to unmanned aerial vehicle body profile Difference, will be made of the production and processing of Mold Making material using mold engraving machine.
Further, die transition area, the die transition area are correspondingly provided in the upper die holder, lower mold and internal model Congruence is carried out at fuselage profile maximum secting area for upper die holder, lower mold or internal model to expand long 20mm and formed.
Further, it is bolted between the upper die holder and lower die holder.
The present invention has the advantages that
1, the unmanned aerial vehicle body shell produced using method proposed by the invention, can guarantee that body shell has Good aerodynamic characteristic and aesthetics, so that it is guaranteed that the flying quality of unmanned plane, makes unmanned plane have broader practice range. 2, method proposed by the invention has been taken into account in current unmanned plane development process to body shell intensity, good aerodynamic characteristic, light Various composite requests such as matter, aesthetics, simple to install, detachable.3, the present invention makes to make by setting die transition area The body shell made is divided into the shell front not being in contact each other and rear, connects convenient for cutting and fuselage installation, To realize simple to install and dismountable demand.4, the unmanned aerial vehicle body shell produced using the method for the present invention can be full While foot such unmanned plane application demand, the structure gross weight of shell is reduced to the maximum extent.
Detailed description of the invention
By reading the following detailed description of the preferred embodiment, various other advantages and benefits are common for this field Technical staff will become clear.The drawings are only for the purpose of illustrating a preferred embodiment, and is not considered as to the present invention Limitation.And throughout the drawings, the same reference numbers will be used to refer to the same parts.In the accompanying drawings:
Fig. 1 is the schematic diagram of the mold of the embodiment of the present invention;
Fig. 2 is the schematic diagram of the internal model of the embodiment of the present invention;
Fig. 3 is the schematic diagram of the structure of unmanned plane machine entirety.
The paraphrase respectively marked in above-mentioned attached drawing is as follows:
1: upper die holder, 2: lower die holder, 3: internal model, 4: shell laminated material, 5: die transition area, 6: shell connecting hole.
Specific embodiment
The illustrative embodiments of the disclosure are more fully described below with reference to accompanying drawings.Although showing this public affairs in attached drawing The illustrative embodiments opened, it being understood, however, that may be realized in various forms the disclosure without the reality that should be illustrated here The mode of applying is limited.It is to be able to thoroughly understand the disclosure on the contrary, providing these embodiments, and can be by this public affairs The range opened is fully disclosed to those skilled in the art.
It should be understood that term used herein merely for description particular example embodiment purpose, and have no intention into Row limitation.Unless the context clearly indicates otherwise, otherwise singular " one " as used in the text, "one" and " described " Can also indicate to include plural form.The terms "include", "comprise", " containing " and " having " are inclusives, and therefore It indicates the presence of stated feature, step, operations, elements, and/or components, but presence or addition one or more is not precluded A other feature, step, operation, component, assembly unit, and/or their combination.Method and step, process, the Yi Jicao of described in the text It is not interpreted as that them is necessarily required to execute with described or explanation particular order, executes sequence unless explicitly stated otherwise.Also answer The step of working as understanding, can be used additionally or alternatively.
The invention proposes a kind of methods for making unmanned aerial vehicle body shell, comprising the following steps:
1) mold for making unmanned aerial vehicle body shell is designed and processes, the mold includes upper die holder 1, lower die holder 2 and internal model 3, internal model 3 is used for the laying of shell laminated material 4, is removably connected between upper die holder 1 and lower die holder 2, upper die holder 1 with lower die holder 2 when connecting, and upper die holder 1 and lower die holder 2 carry out tieing up the type of shape when being encircled into for solidify shell laminated material 4 Chamber;Die transition area 5 is equipped in upper die holder 1, lower mold and internal model 3, die transition area 5 is corresponding mold in fuselage profile Congruence is carried out at maximum secting area to expand long and formed;
2) raw material of unmanned aerial vehicle body shell are surround to laying in internal model 3, wherein in the die transition area 5 of internal model 3 Certain interval distance is stayed in intermediate region when laying, to guarantee the unmanned aerial vehicle body shell produced as front shell and rear portion shell It body and does not contact each other;
3) internal model 3 is placed in the type chamber that upper die holder 1 and lower die holder 2 surround, and upper die holder 1 and lower die holder 2 is consolidated Fixed connection;
4) mold is integrally put into curing molding autoclave to be heating and curing, thus before obtaining unmanned aerial vehicle body shell Portion's shell and aft case.
It is good can to guarantee that body shell has for the unmanned aerial vehicle body shell produced using method proposed by the invention Good aerodynamic characteristic and aesthetics, so that it is guaranteed that the flying quality of unmanned plane, makes unmanned plane have broader practice range.
In above-described embodiment, it is preferable that the method for making unmanned aerial vehicle body shell is further comprising the steps of:
5) flash and sharp parts of front shell and aft case are removed;
6) shell connecting hole 6 is processed in front shell and aft case;
7) cleaning treatment is carried out with surface of the alcohol to front shell and aft case.
In above-described embodiment, it is preferable that the length in die transition area 5 is 20mm.
In above-described embodiment, it is preferable that in step 2) in 5 laying of die transition area of internal model 3, stayed in intermediate region Clearance distance is 10mm.
In above-described embodiment, it is preferable that when mold being put into curing molding autoclave in step 4) being heating and curing, add Hot temperature is 135 DEG C, and heating-up time control was at 45 minutes, and in 1.1 standard atmospheric pressures, heating time is 2 hours for pressure control.
In above-described embodiment, it is preferable that shell laminated material 4 be carbon cloth, glass fabric, aryl fiber cloth or Vectran fiber cloth.
In above-described embodiment, it is preferable that the material that the making material of mold can select deformation affected by environment small, such as Metal, solid wood etc..
Based on the above method, the invention also provides a kind of for making the mold of unmanned aerial vehicle body shell, including upper mold Seat 1, lower die holder 2 and internal model 3, internal model 3 are used for the laying of shell laminated material 4, between upper die holder 1 and lower die holder 2 removably Connection, when upper die holder 1 connect with lower die holder 2, when upper die holder 1 and lower die holder 2 are encircled into for the solidification of shell laminated material 4 into The type chamber of row dimension shape.
In above-described embodiment, it is preferable that upper die holder 1, lower die holder 2 and internal model 3 are according to unmanned aerial vehicle body profile, in conjunction with mould Have manufacturing tolerance, it will be made of the production and processing of Mold Making material using mold engraving machine.
In above-described embodiment, it is preferable that be correspondingly provided with die transition area 5, mold in upper die holder 1, lower mold and internal model 3 Transition region 5 is that upper die holder 1, lower mold or internal model 3 carry out at fuselage profile maximum secting area the long 20mm of congruence expansion and formed.
In above-described embodiment, it is preferable that be bolted between upper die holder 1 and lower die holder 2.
Further, the mold for making unmanned aerial vehicle body shell proposed by the invention is before design, first with Modeling of aircraft software carries out unmanned aerial vehicle body design according to unmanned plane general design requirement, to establish complete fuselage profile Figure recycles modeling of aircraft software design to go out mold later.Modeling of aircraft software is mainly some common drawing softwares, such as CATIA, UG etc..
The foregoing is only a preferred embodiment of the present invention, but scope of protection of the present invention is not limited thereto, In the technical scope disclosed by the present invention, any changes or substitutions that can be easily thought of by anyone skilled in the art, It should be covered by the protection scope of the present invention.Therefore, protection scope of the present invention should be with the protection model of the claim Subject to enclosing.

Claims (10)

1. a kind of method for making unmanned aerial vehicle body shell, comprising the following steps:
1) design and process mold for making unmanned aerial vehicle body shell, the mold includes upper die holder, lower die holder and interior Mould, internal model are used for the laying of shell laminated material, are removably connected between upper die holder and lower die holder, and upper die holder and lower die holder connect When connecing, upper die holder and lower die holder carry out the type chamber of dimension shape when being encircled into for solidifying to shell laminated material;Upper die holder, lower mold Be equipped with die transition area in internal model, die transition area is that corresponding mold carries out congruence at fuselage profile maximum secting area Expand long and is formed;
2) raw material of unmanned aerial vehicle body shell are surround to laying in internal model, wherein in the die transition area laying of internal model Stay certain interval distance in intermediate region, using guarantee the unmanned aerial vehicle body shell produced as front shell and aft case and that This is not contacted;
3) internal model is placed in the type chamber that upper die holder and lower die holder surround, and upper die holder and lower die holder is fixedly connected;
4) mold is integrally put into curing molding autoclave to be heating and curing, to obtain the front shell of unmanned aerial vehicle body shell Body and aft case.
2. the method according to claim 1 for making unmanned aerial vehicle body shell, which is characterized in that the method is also wrapped Include following steps:
5) flash and sharp parts of front shell and aft case are removed;
6) shell connecting hole is processed in front shell and aft case;
7) cleaning treatment is carried out with surface of the alcohol to front shell and aft case.
3. the method according to claim 1 for making unmanned aerial vehicle body shell, which is characterized in that the die transition The length in area is 20mm.
4. the method according to claim 3 for making unmanned aerial vehicle body shell, which is characterized in that in the step 2) It is 10mm in the clearance distance that intermediate region is stayed in the die transition area laying of internal model.
5. the method according to claim 1 for making unmanned aerial vehicle body shell, which is characterized in that in the step 4) When mold being put into curing molding autoclave being heating and curing, heating temperature is 135 DEG C, and the heating-up time controlled at 45 minutes, In 1.1 standard atmospheric pressures, heating time is 2 hours for pressure control.
6. the method according to claim 1 for making unmanned aerial vehicle body shell, which is characterized in that shell laminated material For carbon cloth, glass fabric, aryl fiber cloth or Vectran fiber cloth.
7. a kind of for making the mold of unmanned aerial vehicle body shell, which is characterized in that including upper die holder, lower die holder and internal model, institute State internal model for shell laminated material laying, be removably connected between the upper die holder and lower die holder, the upper die holder with When the lower die holder connects, the upper die holder and lower die holder carry out the type of dimension shape when being encircled into for solidifying to shell laminated material Chamber.
8. according to claim 7 for making the mold of unmanned aerial vehicle body shell, which is characterized in that the upper die holder, Lower die holder and internal model are according to unmanned aerial vehicle body profile, in conjunction with mold manufacturing tolerance, using mold engraving machine by Mold Making Made of material production and processing.
9. according to claim 7 or 8 for making the mold of unmanned aerial vehicle body shell, which is characterized in that the upper mold Die transition area is correspondingly provided in seat, lower mold and internal model, the die transition area is upper die holder, lower mold or internal model in machine Congruence is carried out at body profile maximum secting area to expand long 20mm and formed.
10. according to claim 7 or 8 for making the mold of unmanned aerial vehicle body shell, which is characterized in that the upper mold It is bolted between seat and lower die holder.
CN201811493344.5A 2018-12-07 2018-12-07 Method and mold for manufacturing unmanned aerial vehicle body shell Active CN109501060B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201811493344.5A CN109501060B (en) 2018-12-07 2018-12-07 Method and mold for manufacturing unmanned aerial vehicle body shell

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201811493344.5A CN109501060B (en) 2018-12-07 2018-12-07 Method and mold for manufacturing unmanned aerial vehicle body shell

Publications (2)

Publication Number Publication Date
CN109501060A true CN109501060A (en) 2019-03-22
CN109501060B CN109501060B (en) 2020-02-07

Family

ID=65753022

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201811493344.5A Active CN109501060B (en) 2018-12-07 2018-12-07 Method and mold for manufacturing unmanned aerial vehicle body shell

Country Status (1)

Country Link
CN (1) CN109501060B (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006289445A (en) * 2005-04-12 2006-10-26 Nippon Steel Corp Mold for hydroforming
CN101870172A (en) * 2010-06-09 2010-10-27 哈尔滨工业大学 Preparation mould of carbon fiber composite material casing of airplane and aircraft and forming method thereof
CN204414642U (en) * 2015-01-06 2015-06-24 王梁 The mold pressing assembling die of replaceable internal mold
CN105563851A (en) * 2016-02-04 2016-05-11 上海晋飞新材料科技有限公司 Moulding process for fuselage of UAV (Unmanned Aerial Vehicle)
CN106217697A (en) * 2016-08-30 2016-12-14 山东双科技股份有限公司 A kind of mould of composite many rotor wing unmanned aerial vehicles horn and preparation method thereof

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006289445A (en) * 2005-04-12 2006-10-26 Nippon Steel Corp Mold for hydroforming
CN101870172A (en) * 2010-06-09 2010-10-27 哈尔滨工业大学 Preparation mould of carbon fiber composite material casing of airplane and aircraft and forming method thereof
CN204414642U (en) * 2015-01-06 2015-06-24 王梁 The mold pressing assembling die of replaceable internal mold
CN105563851A (en) * 2016-02-04 2016-05-11 上海晋飞新材料科技有限公司 Moulding process for fuselage of UAV (Unmanned Aerial Vehicle)
CN106217697A (en) * 2016-08-30 2016-12-14 山东双科技股份有限公司 A kind of mould of composite many rotor wing unmanned aerial vehicles horn and preparation method thereof

Also Published As

Publication number Publication date
CN109501060B (en) 2020-02-07

Similar Documents

Publication Publication Date Title
CN104626605B (en) Composite material wing integral molding technological method and composite material wing integral molding tool
CN103221305B (en) The cabin porthole with program control distortion, the method manufacturing this kind of porthole and comprise the aerocraft of this kind of porthole
KR101930609B1 (en) Method and apparatus for producing a sandwich component, and sandwich component
CN111186143B (en) Integrated forming process for composite nose cone of unmanned aerial vehicle electric cabin
CN106828967A (en) Full-height foaming structure multi-rotor unmanned aerial vehicle manufacture method
CN103407170B (en) A kind of preparation method of satellite antenna reflecting surface
CN108959744A (en) A kind of small and medium size unmanned aerial vehicles composite wing wing box manufacturing method
CN110193957A (en) A kind of small drone composite aileron moulding technique
CN104290338A (en) Method for realization of co-curing of reinforcing rib web composite produced part by high strength soft tooling
CN103231464A (en) Honeycomb preforming method for large-curvature composite material interlayer piece
CN108943766A (en) Co-bonding forming process for T-shaped reinforced wall plate made of composite material
US9744700B2 (en) Methods and apparatus for forming workpiece components
CN103935042B (en) The manufacture method of the hollow rotor of unmanned vehicle and hollow rotor
CN104626548A (en) Composite-material vertical fin combination method of unmanned aerial vehicle
CN103963288A (en) Method for assembling elements of composite material for aircrafts, capable of releasing stress in the elements
CN107775849A (en) A kind of 3D printing foundry resin mould process
CN102848579A (en) Manufacturing method of double-sided honeycomb sandwich composite material product
CN109501060A (en) For making the method and mold of unmanned aerial vehicle body shell
CN203109064U (en) Assembled die for cold punch forming of automobile body covering part
CN110757830B (en) Thermal diaphragm forming method for hat-shaped stringer
CN211869726U (en) Universal composite material repairing instrument for aviation and aircraft
US8491829B2 (en) Method of producing a structural part made from a thermosetting resin by drawing
CN106217906A (en) A kind of global formation composite shape for hat muscle manufacture method
CN204869434U (en) Preceding hot briquetting mould that gives sound insulation and fill up that encloses
CN211105742U (en) Six rotor unmanned aerial vehicle fuselage moulds of integrated molding

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
GR01 Patent grant
GR01 Patent grant