CN215550611U - Male die assembly and die - Google Patents

Male die assembly and die Download PDF

Info

Publication number
CN215550611U
CN215550611U CN202120572926.3U CN202120572926U CN215550611U CN 215550611 U CN215550611 U CN 215550611U CN 202120572926 U CN202120572926 U CN 202120572926U CN 215550611 U CN215550611 U CN 215550611U
Authority
CN
China
Prior art keywords
male
plate
connector
male die
cavity
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.)
Active
Application number
CN202120572926.3U
Other languages
Chinese (zh)
Inventor
张亮
吴陈卫
黄海锋
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.)
Shenzhen Baoxinchuang Information Technology Co ltd
Original Assignee
Shenzhen Baoxinchuang Technology 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 Shenzhen Baoxinchuang Technology Co Ltd filed Critical Shenzhen Baoxinchuang Technology Co Ltd
Priority to CN202120572926.3U priority Critical patent/CN215550611U/en
Application granted granted Critical
Publication of CN215550611U publication Critical patent/CN215550611U/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Landscapes

  • Moulds For Moulding Plastics Or The Like (AREA)

Abstract

The utility model discloses a male die component and a die, wherein the male die component comprises: the male die plate is provided with a male die cavity; an exhaust channel is arranged in the male die plate and is communicated with the male die cavity; the moving part, the moving part includes connector and movable rod, the connector set up in the one end of movable rod, the movable rod activity set up in the exhaust passage. Through be formed with the exhaust passage on public mould subassembly, the exhaust passage with public mould die cavity intercommunication set up the moving part in the exhaust passage, the position of moving part is removed in the in-process accessible of moulding plastics, can make in the exhaust passage is put into to the connector, because the connector is more than or equal to the internal diameter of exhaust passage, the connector removes extremely in the exhaust passage, it is sealed the exhaust passage, and then prevent the infiltration of material bits or greasy dirt in the exhaust passage, and then guarantee the exhaust effect of public mould subassembly.

Description

Male die assembly and die
Technical Field
The utility model belongs to the technical field of dies, and particularly relates to a male die assembly and a die.
Background
The traditional mould usually adopts an exhaust inlet or exhaust steel for exhaust, and the exhaust inlet or exhaust steel is arranged on the core insert and is exposed on the surface of the core insert; during the production process, material scraps or oil stains are easy to permeate into the exhaust inlet or exhaust steel, so that the exhaust effect is reduced; the unsmooth gas is removed, high pressure is formed in the cavity and permeates into the die body under a certain compression degree, so that quality defects such as air holes, cavities, loose tissues and the like are caused, and the yield of products is influenced.
SUMMERY OF THE UTILITY MODEL
The main purpose of the embodiments of the present invention is to provide a male mold assembly and a mold, aiming to improve the defect of low exhaust effect of the male mold core.
In order to solve the above technical problems, the present invention provides a male mold assembly, which includes: the male die plate is provided with a male die cavity; an exhaust channel is arranged in the male die plate and is communicated with the male die cavity; the movable part comprises a connector and a movable rod, the connector is arranged at one end of the movable rod, the movable rod is movably arranged in the exhaust channel and drives the connector to move towards the exhaust channel when moving along the exhaust channel, or pushes the connector to move towards the male die cavity; the diameter of the movable rod is smaller than the inner diameter of the exhaust channel, and the connecting head is larger than or equal to the inner diameter of the exhaust channel.
Further, the connector is in a round table shape, and the upper bottom surface of the connector is connected with the movable rod.
Furthermore, a chamfer is arranged at the joint of the channel wall of the exhaust channel and the cavity wall of the male die cavity, or a limiting piece is arranged in the exhaust channel.
Furthermore, a driving device is arranged on the movable rod, and one end of the movable rod, which is far away from the connector, is connected with the driving device; the driving device is fixed on the male template and is positioned in the exhaust channel.
Furthermore, the driving device is an air pump, and one end of the movable rod, which is far away from the connector, is connected with a piston rod of the air pump; the male die plate is also provided with a gas circuit inlet and a gas circuit outlet, and the gas circuit inlet and the gas circuit outlet are respectively communicated with the cylinder of the air pump.
Further, the male mold assembly further comprises: the lower fixing plate is connected to the surface of the male die plate, which is far away from the cavity of the male die; the thimble structure is arranged between the male template and the lower fixing plate; the thimble structure comprises an upper thimble plate and a lower thimble plate, the lower thimble plate is arranged on the lower fixing plate, and the upper thimble plate is connected with the lower thimble plate; the die leg is arranged between the male die plate and the lower fixing plate and used for connecting the male die plate and the lower fixing plate.
The utility model also provides a mold, comprising: the female die assembly is internally provided with a female die cavity; the male die assembly as described above, the male die assembly being connected to the female die assembly; and the male die cavity is in butt joint with the female die cavity to form a die cavity.
Further, the master mold assembly further comprises: a master template on which the master mold cavity is formed; and the upper fixing plate is connected to one side of the female die plate, which deviates from the cavity of the female die.
Further, the master mold assembly further comprises: at least one runner pipe fixed on the upper fixing plate; and is communicated with the female mold cavity through a stub bar; the hot runner plate is arranged between the upper fixing plate and the female template; the hot runner plate is internally provided with a runner for heat conduction liquid to flow, and the runner surrounds the runner pipe.
Further, the mold further comprises: and the male die assembly is connected with the female die assembly through the positioning piece.
The embodiment of the utility model provides a male die component and a die, wherein an exhaust channel is formed on the male die component, the exhaust channel is communicated with a male die cavity, a movable part is arranged in the exhaust channel, the position of the movable part can be moved in the injection molding process, so that a connector can be placed in the exhaust channel, and the connector moves into the exhaust channel to seal the exhaust channel due to the fact that the connector is larger than or equal to the inner diameter of the exhaust channel, so that material scraps or oil stains are prevented from permeating into the exhaust channel, and the exhaust effect of the male die component is further ensured.
Drawings
FIG. 1 is a schematic structural view of a male mold assembly according to the present invention;
fig. 2 is a schematic structural view of the mold of the present invention.
The reference numbers illustrate:
reference numerals Name (R) Reference numerals Name (R)
100 Male die assembly 33 Gas path outlet
11 Male template 41 Lower fixing plate
12 Male die cavity 42 Thimble structure
13 Exhaust passage 43 Mould foot
21 Movable part 51 Female die assembly
22 Connecting head 52 Mother template
23 Movable rod 53 Upper fixing plate
31 Drive device 54 Hot runner plate
32 Gas path inlet
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the utility model and are not intended to limit the utility model.
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. 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.
It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.
In addition, the descriptions related to "first", "second", etc. in the present invention are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
As shown in fig. 1, the present invention discloses a male mold assembly, wherein the male mold assembly 100 comprises: the male die plate 11 is provided with a male die cavity 12; an exhaust channel 13 is arranged in the male die plate 11, and the exhaust channel 13 is communicated with the male die cavity 12; the movable part 21 comprises a connector 22 and a movable rod 23, the connector 22 is arranged at one end of the movable rod 23, and the movable rod 23 is movably arranged in the exhaust channel 13 and drives the connector 22 to move towards the exhaust channel 13 when moving along the exhaust channel 13 or pushes the connector 22 to move towards the male mold cavity 12; the diameter of the movable rod 23 is smaller than the inner diameter of the exhaust channel 13, and the connecting head 22 is larger than or equal to the inner diameter of the exhaust channel 13.
It should be noted that, in this embodiment, the exhaust inlet of the conventional mold has no closed exhaust inlet, so that gas in the cavity can flow out of the exhaust inlet during injection molding, and after exhaust, the exhaust inlet is easily penetrated by chips or oil stains due to the absence of the closed air inlet end of the exhaust inlet, so that the problem of unsmooth exhaust of the exhaust inlet during next use occurs. The utility model provides a male die component, wherein an exhaust channel 13 is formed on a male die component 100, the exhaust channel 13 is communicated with a male die cavity 12, a movable piece 21 is arranged in the exhaust channel 13, a connector 22 can be placed in the exhaust channel 13 by moving the position of the movable piece 21 in the injection molding process, and the connector 22 moves into the exhaust channel 13 to seal the exhaust channel 13 because the connector is larger than or equal to the inner diameter of the exhaust channel 13, so that material scraps or oil stains are prevented from permeating into the exhaust channel 13, and the exhaust effect of the male die component 100 is further ensured.
Specifically, the movable rod 23 is movably disposed in the exhaust channel 13, when the movable rod 23 drives the connector 22 to move along the exhaust channel 13, and when the connector 22 wants to move the male mold cavity 12, because the diameter of the movable rod 23 is smaller than the inner diameter of the exhaust channel 13, the gas in the male mold cavity 12 can flow out of the male mold plate 11 from the gap between the movable rod 23 and the channel wall of the exhaust channel 13; when the injection molding is to be completed, the connector 22 moves to the exhaust channel 13 along with the movable rod 23, and moves to the exhaust channel 13, and because the connector 22 is larger than or equal to the inner diameter of the exhaust channel 13, the connector 22 can seal the exhaust channel 13, and material scraps and oil dirt are prevented from entering the exhaust channel 13.
Further, as shown in fig. 1, the connecting head 22 is in a circular truncated cone shape, and an upper bottom surface of the connecting head 22 is connected to the movable rod 23.
It should be noted that, in this embodiment, the connecting head 22 is set to be a circular truncated cone with unequal upper and lower bottom surfaces, and one end of the smaller bottom surface is connected to the movable rod 23, so that when the movable rod 23 moves in the exhaust channel 13 and drives the connecting head 22 to move toward the exhaust channel 13, the connecting head 22 can better enter the exhaust channel 13, and because the side edge of the connecting head 22 is a bevel edge, the connecting head 22 can more easily move into the exhaust channel 13 when moving to the exhaust channel 13; when the connector 22 moves into the exhaust channel 13 partially or completely, the exhaust channel 13 can be better sealed, and material scraps are prevented from entering the exhaust channel 13, so that the exhaust effect of the exhaust channel 13 is influenced; a good venting effect is obtained each time the male mold assembly 100 is used.
Further, the channel wall of the exhaust channel 13 is provided with a chamfer at the connection with the cavity wall of the male mold cavity 12, or a limiting member is provided in the exhaust channel 13.
It should be noted that, in this embodiment, the channel wall of the exhaust channel 13 is provided with a chamfer adapted to the inclined side surface of the connecting head 22, so that the connecting head 22 can abut against the chamfer provided on the channel wall of the exhaust channel 13 when moving into the exhaust channel 13, and the connecting head 22 is prevented from penetrating into the exhaust channel 13, and further the exhaust channel 13 is prevented from being penetrated by material scraps; and the chamfer with during the connector 22 butt, have better leakproofness, connector 22 seals more easily exhaust passage 13.
In a possible embodiment, when the diameter of the lower bottom surface (the bottom surface with the larger diameter) of the connector 22 is the same as the diameter of the exhaust passage 13, in order to prevent the connector 22 from completely falling into the exhaust passage 13, a limiting member is arranged in the exhaust passage 13, and when the upper bottom surface of the connector 22 is just parallel to the cavity wall of the male mold cavity 12, the limiting member abuts against the connector 22 to prevent the connector 22 from falling into the exhaust passage 13; the limiting piece protrudes out of the channel wall of the exhaust channel 13, and when the upper bottom surface of the connector 22 is just parallel to the cavity wall of the male mold cavity 12, the upper bottom surface of the connector 22 abuts against the upper bottom surface of the connector 22, so that the connector 22 is prevented from continuously moving into the exhaust channel 13.
Further, as shown in fig. 1, a driving device 31 is disposed on the movable rod 23, and one end of the movable rod 23, which is far away from the connector 22, is connected to the driving device 31; the driving device 31 is fixed on the male die plate 11 and is positioned in the exhaust passage 13.
It should be noted that, in this embodiment, the movable rod 23 is provided with a driving device 31, the driving device 31 provides power to drive the movable rod 23 to move in the exhaust passage 13, so that the connector 22 moves towards the exhaust passage 13, or the connector 22 is pushed to move in the male mold cavity 12.
Specifically, the driving device 31 is fixed on the core plate 11 and located in the exhaust channel 13, and the driving device 31 is arranged in the exhaust channel 13, so that the occupied position is small, and the fixing arrangement is convenient.
Further, as shown in fig. 1, the driving device 31 is an air pump, and one end of the movable rod 23, which is far away from the connector 22, is connected to a piston rod of the air pump; the male die plate 11 is further provided with an air path inlet 32 and an air path outlet 33, and the air path inlet 32 and the air path outlet 33 are respectively communicated with the air cylinder of the air pump.
It should be noted that, in this embodiment, the driving device 31 is an air cylinder, so that the driving device 31 is conveniently disposed in the exhaust passage 13, and a piston rod of the air pump reciprocates in the exhaust passage 13 according to the action of the air cylinder to drive the movable rod 23 and the connector 22 to move between the exhaust passage 13 and the male mold cavity 12; the cylinder is provided with an air inlet valve and an air outlet valve, when the air inlet valve is opened, air is collected in the cylinder to generate power, the piston rod is driven to move, and the connector 22 is driven to move towards the male die cavity 12; when an air outlet valve of the air cylinder is opened, air in the air cylinder flows out of the air outlet valve to drive the racing rod to move, and further drive the connector 22 to move towards the exhaust channel 13; and an air inlet valve and an air outlet valve of the air cylinder are respectively communicated with the air path inlet 32 and the air path outlet 33.
Further, as shown in fig. 1, the male mold assembly 100 further includes: the lower fixing plate 41 is connected to the surface, away from the male die cavity 12, of the male die plate 11; the thimble structure 42, the thimble structure 42 is set up between said male template 11 and said lower fixed plate 41; the thimble structure 42 comprises an upper thimble plate and a lower thimble plate, the lower thimble plate is arranged on the lower fixing plate 41, and the upper thimble plate is connected with the lower thimble plate; and the mold leg 43 is arranged between the male mold plate 11 and the lower fixing plate 41, and is used for connecting the male mold plate 11 and the lower fixing plate 41.
In this embodiment, the lower fixing plate 41 is disposed at the bottom of the core plate 11, the lower fixing plate 41 is disposed with a driving fixing plate corresponding to the exhaust channel 13, and the bottom of the driving device 31 is fixed on the driving fixing plate; the mold leg 43 is supported between the lower fixing plate 41 and the male mold plate 11, and a certain space is formed between the fixing plate 41 and the male mold plate 11 for movable mold drawing; thimble structure 42 establishes on fixed plate 41, and be connected in public mould cavity 12 for separate the product from the mould, thimble structure 42 includes thimble board and lower thimble board, lower thimble board establishes on lower fixed plate 41, go up the thimble board with lower thimble board is connected.
The present invention also provides a mold, as shown in fig. 2, comprising: a master mold assembly 51 having a master mold cavity formed within the master mold assembly 51; the male mold half 100 as described above, the male mold half 100 being connected to the female mold half 100; the male mold cavity 12 is in butt joint with the female mold cavity to form a mold cavity.
In this embodiment, the mold includes a female mold component 51 and a male mold component 100, and the male mold component 100 is connected to the female mold component 100; the male die cavity is in butt joint with the female die cavity to form a die cavity, and the die cavity is used for opening a product.
Further, as shown in fig. 2, the master mold assembly 51 further includes: a master template 52, the master mold cavity being formed on the master template 52; and the upper fixing plate 53 is connected to one side, away from the cavity of the female die, of the female die plate 52, and the upper fixing plate 53 is connected to the other side, away from the cavity of the female die, of the female die plate 52.
In this embodiment, the female mold plate 52 is fixed to the upper fixing plate 53, the female mold cavity is formed in the female mold plate 52, when the female mold assembly 51 is butted with the male mold assembly 100, the female mold cavity is butted with the male mold cavity 12 to form a mold cavity, and a product is formed by injection molding of the mold cavity; the upper fixing plate 53 is provided with a heat insulation plate.
Further, as shown in fig. 2, the master mold assembly 51 further includes: at least one flow channel pipe fixed on the upper fixing plate 53; and is communicated with the female mold cavity through a stub bar; a hot runner plate 54, the hot runner plate 54 being disposed between the upper fixing plate 53 and the female mold plate 52; the hot runner plate 54 is provided therein with a runner through which a heat conductive liquid flows, and the runner is disposed around the runner pipe.
In this embodiment, when the runner pipe is used for injecting the mold, the injection liquid flows through the runner pipe, and the injection liquid flows into the female mold cavity through the stub bar and flows into the male mold cavity 12 from the female mold cavity; finally, performing injection molding on the product; the hot runner plate 54 is disposed between the upper fixing plate 53 and the female mold plate 52, and is used to cool the runner pipe, and a runner for flowing heat transfer liquid is disposed in the hot runner plate 54, and the runner surrounds the runner pipe, so as to cool the runner pipe and prevent the runner pipe from overheating.
Further, as shown in fig. 2, the mold further includes: and the male die assembly 100 and the female die assembly 51 are connected through the positioning piece 55.
In this embodiment, the mold includes a positioning element 55, and the positioning element 55 is connected between the male mold assembly 100 and the female mold assembly 51 and is used for positioning a positional relationship between the male mold assembly 100 and the female mold assembly 51.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (10)

1. A male mold assembly, comprising:
the male die plate is provided with a male die cavity; an exhaust channel is arranged in the male die plate and is communicated with the male die cavity;
the movable part comprises a connector and a movable rod, the connector is arranged at one end of the movable rod, the movable rod is movably arranged in the exhaust channel and drives the connector to move towards the exhaust channel when moving along the exhaust channel, or pushes the connector to move towards the male die cavity;
the diameter of the movable rod is smaller than the inner diameter of the exhaust channel, and the connecting head is larger than or equal to the inner diameter of the exhaust channel.
2. The male die assembly of claim 1, wherein the connector is shaped like a circular truncated cone, and an upper bottom surface of the connector is connected with the movable rod.
3. The male mold assembly according to claim 2, wherein the channel wall of the vent channel is chamfered at the junction with the cavity wall of the male mold cavity or a stop is provided in the vent channel.
4. The male die assembly according to claim 1, wherein the movable rod is provided with a driving device, and one end of the movable rod, which is far away from the connector, is connected with the driving device; the driving device is fixed on the male template and is positioned in the exhaust channel.
5. The male die assembly according to claim 4, wherein the driving device is an air pump, and one end of the movable rod, which is far away from the connector, is connected with a piston rod of the air pump; the male die plate is also provided with a gas circuit inlet and a gas circuit outlet, and the gas circuit inlet and the gas circuit outlet are respectively communicated with the cylinder of the air pump.
6. The male mold assembly according to claim 1, further comprising:
the lower fixing plate is connected to the surface of the male die plate, which is far away from the cavity of the male die;
the thimble structure is arranged between the male template and the lower fixing plate; the thimble structure comprises an upper thimble plate and a lower thimble plate, the lower thimble plate is arranged on the lower fixing plate, and the upper thimble plate is connected with the lower thimble plate;
the die leg is arranged between the male die plate and the lower fixing plate and used for connecting the male die plate and the lower fixing plate.
7. A mold, characterized in that the mold comprises:
the female die assembly is internally provided with a female die cavity;
the male mold member of claims 1-6, connected to the female mold member; and the male die cavity is in butt joint with the female die cavity to form a die cavity.
8. The male mold assembly of claim 7, wherein the female mold assembly further comprises:
a master template on which the master mold cavity is formed;
and the upper fixing plate is connected to one side of the female die plate, which deviates from the cavity of the female die.
9. The male mold assembly of claim 8, wherein the female mold assembly further comprises:
at least one runner pipe fixed on the upper fixing plate; and is communicated with the female mold cavity through a stub bar;
the hot runner plate is arranged between the upper fixing plate and the female template;
the hot runner plate is internally provided with a runner for heat conduction liquid to flow, and the runner surrounds the runner pipe.
10. The male mold assembly of claim 8, wherein the mold further comprises:
and the male die assembly is connected with the female die assembly through the positioning piece.
CN202120572926.3U 2021-03-19 2021-03-19 Male die assembly and die Active CN215550611U (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202120572926.3U CN215550611U (en) 2021-03-19 2021-03-19 Male die assembly and die

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202120572926.3U CN215550611U (en) 2021-03-19 2021-03-19 Male die assembly and die

Publications (1)

Publication Number Publication Date
CN215550611U true CN215550611U (en) 2022-01-18

Family

ID=79854460

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202120572926.3U Active CN215550611U (en) 2021-03-19 2021-03-19 Male die assembly and die

Country Status (1)

Country Link
CN (1) CN215550611U (en)

Similar Documents

Publication Publication Date Title
CN201544424U (en) Integrated cylinder
CN215550611U (en) Male die assembly and die
CN215434896U (en) Injection molding mold for automobile door handle
CN201183296Y (en) Plastic rubber mould with cooling water channel
CN205631254U (en) Synchronous injection mold with many types of chamber
CN215703734U (en) Air exhaust structure for mold cavity
CN210851107U (en) Injection mold for cooling down automobile instrument panel brim area
CN113183421B (en) Cooling water joint for ejector rod
CN212826538U (en) Helmet production device
CN218640211U (en) Plastic injection mold
CN220311670U (en) Wax mould cooling arrangement for lost wax casting
CN112339234A (en) Injection mold cooling system convenient for demolding
CN204773339U (en) Pressurize injection mold
CN211662444U (en) Mould cooling system with good cooling effect
CN213082261U (en) Compression type injection mold for automobile rear lamp
CN219650501U (en) Quick radiating injection mold
CN218315081U (en) Cooling mechanism of injection mold
CN220198472U (en) Mould of oblique top heat radiation structure
CN213350832U (en) High-precision metal powder injection molding die
CN212171147U (en) Multi-loop quick water-cooled injection mold
CN216544440U (en) Injection molding mould that cools off fast and impact force is little
CN219968552U (en) PE micropore plate forming die
CN219883127U (en) Iron hook prevents moulding-die
CN217573766U (en) Stamping die for sealing rubber ring of automobile radiator
CN215359705U (en) Cleaning device in thermosetting mould

Legal Events

Date Code Title Description
GR01 Patent grant
GR01 Patent grant
TR01 Transfer of patent right
TR01 Transfer of patent right

Effective date of registration: 20231111

Address after: 518000, 4th Floor, No. 31, Xiacun Community, Gongming Street, Guangming District, Shenzhen City, Guangdong Province

Patentee after: Shenzhen Baoxinchuang Information Technology Co.,Ltd.

Address before: 518000 501-2, building a, wisdom Plaza, 4068 Qiaoxiang Road, Gaofa community, Shahe street, Nanshan District, Shenzhen City, Guangdong Province

Patentee before: Shenzhen baoxinchuang Technology Co.,Ltd.