Sandwich board, processing equipment for preparing sandwich board, and sandwich board installation method

Abstract

The present invention relates to the technical field of plate processing, and discloses a sandwich board, processing equipment for preparing the sandwich board, and a method for installing the sandwich board, including a knocking device, the knocking device including an electric turntable, the lower end of the electric turntable being fixedly connected to an electric push rod, the lower end of the electric push rod being fixedly connected to a support plate, the lower end of the support plate being fixedly connected to a limit block, the front end of the support plate being fixedly connected to a slide rail, the left end of the slide rail being fixedly connected to a motor, the right end of the motor being fixedly connected to a bidirectional screw, the outer surface of the bidirectional screw being threadedly connected to a bracket, and the inner side of the bracket being slidably connected to four electric clamps. In this sandwich board process, an electric clamp is provided to clamp a connector, and then an electric knocking hammer is provided to knock the electric clamp, thereby knocking the connector into an intermediate layer plate through the electric clamp. After the electric clamp releases the connector, it resets under the action of a spring, and the operation can be repeated, thereby achieving the effect of improving work efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of plate processing, in particular to a sandwich board, processing equipment for preparing the sandwich board and a method for installing the sandwich board. Background Art

[0002] Sandwich panels include two layers of panels, one above the other, and a core panel between them. For example, the common honeycomb panel has a honeycomb-shaped core. It is the common name for sandwich core composites. The sandwich core is fixed except for those made of metal sheets, styrofoam or corrugated paper.

[0003] During the production of sandwich panels, adhesive is generally used to bond the three layers of board together. However, the adhesive is prone to debonding over time. Therefore, currently, connectors are mostly added to the sandwich panels to increase their strength. However, the installation of the connectors requires manual operation with a rubber hammer to hammer them into the board. Over time, this can easily cause fatigue, thereby reducing work efficiency.

[0004] To this end, we proposed a sandwich panel process to solve the problem that adding connectors in existing sandwich panel production requires manual operation, which reduces work efficiency. Summary of the Invention

[0005] The object of the present invention is to provide a sandwich panel, a processing device for preparing the sandwich panel and a method for installing the sandwich panel, so as to solve the problem in the above background art that manual operation is required when adding connectors to the existing sandwich panel production, thereby reducing work efficiency.

[0006] In order to solve the above technical problems, the present invention provides the following technical solution: a sandwich panel includes an intermediate layer panel, a top layer panel is provided at the upper end of the intermediate layer panel, a bottom layer panel is provided at the lower end of the intermediate layer panel, a plurality of holes and grooves are provided on the intermediate layer panel, a connecting member is provided in the holes and grooves of the intermediate layer panel, the connecting member includes a cylinder, an arc-shaped plug is fixedly connected to one end of the cylinder, and grooves are provided on the facing sides of the top layer panel and the bottom layer panel.

[0007] Furthermore, the main body of the sandwich board is composed of an intermediate layer board, a top layer board and a bottom layer board. Traditional sandwich boards use adhesives to bond the sandwich boards together, and the sandwich boards are prone to debonding after being used for a period of time. Therefore, a connecting piece is set between the boards for fixation, and the cylinder of the connecting piece is hammered into the hole groove of the intermediate layer board by an electric hammer. Then, the top layer board and the bottom layer board are respectively placed on both sides of the intermediate layer board, and the arc plug is hammered into the grooves of the top layer board and the bottom layer board by an electric hammer to fix them, thereby completing the fixing operation of the sandwich board.

[0008] Preferably, there are two arc-shaped plugs, the two arc-shaped plugs are elastic blocks, the other top end of the arc-shaped plug is set to be conical, and the multiple hole slots on the middle layer plate are opened in opposite directions.

[0009] The two arc plugs are hammered into the grooves of the top layer or the bottom layer by an electric hammer. The arc plugs and the top layer or the bottom layer are squeezed against each other to enhance the friction, thereby connecting with the middle layer. The cone at the top of the arc plug can prevent the top layer or the bottom layer from falling off by locking the notch through the bottom of the cone, thereby enhancing the connection stability of the sandwich panel.

[0010] Preferably, the processing equipment of the sandwich board includes a knocking device, which includes an electric turntable, the lower end of the electric turntable is fixedly connected to an electric push rod, the lower end of the electric push rod is fixedly connected to a support plate, the lower end of the support plate is fixedly connected to a limiting block, the front end of the support plate is fixedly connected to a slide rail, the left end of the slide rail is fixedly connected to a motor, the right end of the motor is fixedly connected to a bidirectional screw, the outer surface of the bidirectional screw is threadedly connected to a bracket, four electric clamps are slidably connected to the inner side of the bracket, a spring is provided between the electric clamp and the bracket, and the bracket is provided with an electric knocking hammer at the front end of the electric clamp.

[0011] Furthermore, during installation, the middle layer is placed on the lower end of the knocking device and fixed, the electric push rod is started, the electric push rod drives the support plate to descend, and the support plate drives the limit block to descend, and the middle layer is squeezed and positioned, so as to avoid deviation when installing the connecting piece, resulting in dislocation, and the connecting piece is clamped on the electric clamp, and the motor is started, and the motor drives the bidirectional screw to rotate, and the bidirectional screw drives the two brackets to move in opposite directions, so that the bracket moves the connecting piece to the front of the hole slot of the middle layer through the electric clamp, and the electric knocking hammer is started, so that the electric knocking hammer continuously knocks the electric clamp, so that the electric clamp slides backward along the bracket, and the electric clamp drives the spring to be compressed. At the same time, the connecting piece is knocked into the middle layer by the electric knocking hammer to complete the installation of the connecting piece and the middle layer, so that the electric clamp loosens the connecting piece. Under the action of spring 1, the electric clamp is driven to reset and the motor is rotated in the opposite direction. The motor drives the two brackets to make opposite movements through the bidirectional screw to avoid movement interference between the brackets and the middle layer during movement. The electric turntable is started to drive the support plate to rotate. The above operation is repeated to install the connecting piece on the back side of the middle layer, so as to facilitate the installation of the connecting piece and improve the installation efficiency. The electric knocking hammer is used to swing back and forth and knock the electric clamp. The electric knocking hammer and the electric clamp belong to the existing technology and will not be described here.

[0012] Preferably, the upper end of the electric turntable is fixedly connected to a pillar, the lower end of the pillar is provided with a workbench, the middle part of the upper end of the workbench is provided with an automatic lifting rod, the upper end of the automatic lifting rod is fixedly connected to a block, the workbench is provided with a baffle in the middle of the block, both ends of the block are fixedly connected to extension plates, and the workbench is fixedly connected to baffles on opposite sides of the two extension plates.

[0013] Furthermore, the pillar is used to support the knocking device, and the workbench is an operating table to facilitate the connection operation. The middle layer is limited by the block, and the middle layer is clamped in the block to complete the preliminary limiting operation of the middle layer. The baffle and the extension plate are used to limit the top layer and the bottom layer. After the installation of the connecting parts and the middle layer is completed, the top layer and the bottom layer are limited in batches, and the middle layer is limited by the limit block. The automatic lifting rod is started to drive the block and the extension plate to descend, and then the electric knocking hammer and the electric clamp are used to knock the top layer or the bottom layer, thereby completing the installation between the middle layer and the top layer or the bottom layer. The baffle is used to support and limit the middle layer to prevent the middle layer from descending with the block, thereby affecting the installation process.

[0014] Preferably, the limit block is set to an L-shaped structure, the front end of the limit block is slidably connected to a sliding rod, the outer surface of the sliding rod is sleeved with a spring 2, the other end of the sliding rod is fixedly connected to an extrusion plate, and the extrusion plate and the facing sides of the limit block are respectively provided with an electromagnet and a magnetic block.

[0015] Furthermore, the limit block is set to an L-shaped structure to avoid interference with the installation of the middle layer and the top layer or the bottom layer. The extrusion plate is supported by the second spring so that the extrusion plate squeezes the middle layer to play a supporting role. At the same time, it avoids the problem of movement interference between the layer and the limit block after the installation of one side of the layer is completed due to direct extrusion positioning. The setting of the electromagnet and the magnetic block facilitates the contraction of the extrusion plate, while driving the second spring to contract.

[0016] Preferably, both ends of the bidirectional screw are slidably connected to the slide rail, and the bracket is slidably connected to the slide rail.

[0017] Furthermore, the slide rails serve to limit the bidirectional screw and the bracket, thereby facilitating the two brackets to move toward or in opposite directions through the rotation of the bidirectional screw.

[0018] Preferably, the bracket is located at the front end of the electric clamp and is slidably connected to a limit plate, the front end of the limit plate is rotatably connected to a screw rod 1, and the front end of the screw rod 1 is fixedly connected to a knob.

[0019] Furthermore, by turning the knob, the knob drives screw 1 to rotate, and screw 1 is threadedly connected to the bracket, thereby controlling the extension and retraction of screw 1, and screw 1 drives the limit plate to move back and forth, thereby limiting the electric clamp and adjusting the movement range, making it easy to adjust according to the thickness of the sandwich panel.

[0020] Preferably, the method for installing the sandwich panel comprises the following steps:

[0021] S1: Use a milling cutter to mill grooves and open holes in the plate;

[0022] S2: Fix the middle layer and use the processing equipment of the sandwich panel to knock the connecting parts into the holes and grooves of the middle layer;

[0023] S3: Connect the top and bottom layers from both ends of the middle layer through connectors.

[0024] Preferably, during S3 , a resin adhesive may be placed between the middle layer and the top layer, and between the middle layer and the bottom layer.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] First, the present invention clamps the connecting piece by setting an electric clamp, and then strikes the electric clamp by setting an electric hammer, so that the connecting piece is knocked into the middle layer plate by the electric clamp. After the electric clamp releases the connecting piece, it resets under the action of a spring, and the operation can be repeated, thereby achieving the effect of improving work efficiency.

[0027] Second, the present invention places the middle layer plate at the lower end of the knocking device and starts the electric push rod, which drives the limit block to descend and clamps the middle layer plate, thereby avoiding offset and misalignment when installing the connecting parts. By starting the electric turntable, the knocking device is driven to rotate and the knocking direction is changed, thereby facilitating the knocking connection operation from both ends of the middle layer plate and improving the installation and connection efficiency.

[0028] Third, the present invention limits the middle layer plate by the clamping block, and clamps the middle layer plate in the clamping block to complete the preliminary limiting operation of the middle layer plate, and cooperates with the baffle plate and the extension plate to limit the top layer plate and the bottom layer plate. After the installation of the connecting parts and the middle layer plate is completed, the top layer plate and the bottom layer plate are limited in batches, and the middle layer plate is limited by the limiting block, and the automatic lifting rod is started to drive the clamping block and the extension plate to descend, and then the electric knocking hammer and the electric clamp are cooperated to knock the top layer plate or the bottom layer plate, thereby completing the installation between the middle layer plate and the top layer plate or the bottom layer plate, thereby realizing convenient limiting of the sandwich panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a three-dimensional diagram of the structure of the present invention;

[0030] Figure 2 A three-dimensional diagram of the intermediate layer of the present invention;

[0031] Figure 3 is a cross-sectional view of the intermediate layer plate of the present invention;

[0032] Figure 4 A three-dimensional diagram of the striking device of the present invention;

[0033] Figure 5 This is a side sectional view of the support plate connection structure of the present invention;

[0034] Figure 6 This is a top sectional view of the bracket of the present invention;

[0035] Figure 7 It is a side sectional view of the base of the present invention.

[0036] Among them: 1. Middle layer; 2. Top layer; 3. Bottom layer; 4. Connector; 401. Cylinder; 402. Arc plug; 5. Knocking device; 501. Electric turntable; 502. Electric push rod; 503. Support plate; 504. Slide rail; 505. Motor; 506. Bidirectional screw; 507. Bracket; 508. Electric clamp; 509. Spring 1; 510. Electric knock hammer; 511. Limit block; 512. Slide rod; 513. Spring 2; 514. Extrusion plate; 515. Electromagnet; 516. Magnetic block; 517. Limit plate; 518. Screw 1; 519. Knob; 6. Pillar; 7. Workbench; 701. Automatic lifting rod; 702. Block; 703. Baffle; 704. Extension plate; 705. Baffle. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the specific embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the specific embodiments described are only part of the present invention, not all of it. Based on the specific embodiments of the present invention, all other specific embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0038] Example 1

[0039] The following is a specific implementation of the sandwich panel.

[0040] See also Figure 1-3The sandwich panel includes an intermediate layer plate 1, a top layer plate 2 is provided at the upper end of the intermediate layer plate 1, a bottom layer plate 3 is provided at the lower end of the intermediate layer plate 1, a hole groove is provided on the intermediate layer plate 1, a connecting member 4 is provided in the hole groove of the intermediate layer plate 1, and the connecting member 4 includes a cylinder 401, one end of the cylinder 401 is fixedly connected to an arc-shaped plug 402, and grooves are provided on the facing sides of the top layer plate 2 and the bottom layer plate 3.

[0041] Through the above technical solution, the main body of the sandwich panel is composed of an intermediate layer panel 1, a top layer panel 2 and a bottom layer panel 3. Traditional sandwich panels use adhesives to bond the sandwich panels together, and the sandwich panels are prone to debonding after being used for a period of time. Therefore, a connector 4 is provided between the panels for fixation. The cylinder 401 of the connector 4 is hammered into the hole groove of the intermediate layer panel 1 by an electric hammer 510, and then the top layer panel 2 and the bottom layer panel 3 are respectively placed on both sides of the intermediate layer panel 1. The arc plug 402 is hammered into the grooves of the top layer panel 2 and the bottom layer panel 3 by the electric hammer 510 to fix them, thereby completing the fixing operation of the sandwich panel.

[0042] See also Figure 3 There are two arc plugs 402, the two arc plugs 402 are elastic blocks, and the other top end of the arc plug 402 is set to be conical.

[0043] Through the above technical solution, the two arc plugs 402 are hammered into the grooves of the top layer 2 or the bottom layer 3 by an electric hammer 510. The arc plugs 402 and the top layer 2 or the bottom layer 3 are squeezed against each other to enhance the friction force, thereby connecting with the middle layer 1. The cone at the top of the arc plug 402 can prevent the top layer 2 or the bottom layer 3 from falling off by locking the notch through the bottom of the cone, thereby enhancing the connection stability of the sandwich panel.

[0044] Example 2

[0045] The following is a specific embodiment of the processing equipment for preparing sandwich panels.

[0046] See also Figure 4-7The processing equipment of the sandwich board includes a knocking device 5, which includes an electric turntable 501, an electric push rod 502 fixedly connected to the lower end of the electric push rod 502, a support plate 503 fixedly connected to the lower end of the support plate 503, a limited block 511 fixedly connected to the front end of the support plate 503, a slide rail 504 fixedly connected to the left end of the slide rail 504, a motor 505 fixedly connected to the right end of the motor 505, a bidirectional screw 506 fixedly connected to the outer surface of the bidirectional screw 506 threadedly connected to a bracket 507, four electric clamps 508 are slidably connected to the inner side of the bracket 507, a spring 509 is provided between the electric clamp 508 and the bracket 507, and the bracket 507 is provided with an electric knocking hammer 510 at the front end of the electric clamp 508.

[0047] When the bracket 507 is in the state of being moved, the electric hammer 510 is started, and the electric hammer 510 continuously strikes the electric clamp 508, thereby causing the electric clamp 508 to slide backward along the bracket 507. The spring 1 509 is compressed, and at the same time, the connecting part 4 is driven to be knocked into the middle layer 1 by the electric hammer 510, completing the installation of the connecting part 4 and the middle layer 1, so that the electric clamp 508 loosens the connecting part 4. Under the action of the spring 1 509, the electric clamp 508 is driven to reset and the motor 505 is rotated in the opposite direction. The motor 505 drives the two brackets 507 to do opposite movements through the bidirectional screw 506 to avoid movement interference between the brackets 507 and the middle layer 1 during the movement. The electric turntable 501 is started to drive the support plate 503 to rotate. The above operation is repeated to install the connecting part 4 on the back side of the middle layer 1, so as to facilitate the installation of the connecting part 4 and improve the installation efficiency. The electric hammer 510 is used to swing back and forth and knock the electric clamp 508. The electric hammer 510 and the electric clamp 508 belong to the existing technology and will not be described here.

[0048] See also Figure 4 、 Figure 7The upper end of the electric turntable 501 is fixedly connected to the pillar 6, and the lower end of the pillar 6 is provided with a workbench 7. An automatic lifting rod 701 is provided in the middle of the upper end of the workbench 7, and the upper end of the automatic lifting rod 701 is fixedly connected to a block 702. The workbench 7 is located in the middle of the block 702 and is provided with a baffle 703. Both ends of the block 702 are fixedly connected to extension plates 704. The workbench 7 is located on the opposite sides of the two extension plates 704 and is fixedly connected with baffles 705.

[0049] Through the above technical solution, the pillar 6 is used to support the knocking device 5, and the workbench 7 is an operating table to facilitate the connection operation. The middle layer 1 is limited by the block 702, and the middle layer 1 is clamped in the block 702 to complete the preliminary limiting operation of the middle layer 1. The baffle 705 and the extension plate 704 cooperate to limit the top layer 2 and the bottom layer 3. After the connection piece 4 and the middle layer 1 are installed, the top layer 2 and the bottom layer 3 are limited in batches. The middle layer 1 is limited by the limit block 511, and the automatic lifting rod 701 is started to drive the block 702 and the extension plate 704 to descend. Then, the electric hammer 510 and the electric clamp 508 are used to knock the top layer 2 or the bottom layer 3 to complete the installation between the middle layer 1 and the top layer 2 or the bottom layer 3. The baffle 703 is used to support and limit the middle layer 1 to prevent the middle layer 1 from descending with the block 702, thereby affecting the installation process.

[0050] See also Figure 6 The limit block 511 is set to an L-shaped structure. The front end of the limit block 511 is slidably connected to a slide rod 512. The outer surface of the slide rod 512 is sleeved with a spring 2 513. The other end of the slide rod 512 is fixedly connected to an extrusion plate 514. The extrusion plate 514 and the facing sides of the limit block 511 are respectively provided with an electromagnet 515 and a magnetic block 516.

[0051] Through the above technical solution, the limit block 511 is set to an L-shaped structure to avoid interference with the installation of the middle layer plate 1 and the top layer plate 2 or the bottom layer plate 3. The extrusion plate 514 is supported by the spring 2 513, so that the extrusion plate 514 squeezes the middle layer plate 1 to play a supporting role. At the same time, it avoids the problem of movement interference between the layer plate and the limit block 511 after the installation of one side of the layer is completed due to direct extrusion positioning. Through the setting of the electromagnet 515 and the magnetic block 516, it is easy to shrink the extrusion plate 514, and at the same time drive the spring 2 513 to shrink.

[0052] See also Figure 5 Both ends of the bidirectional screw 506 are slidably connected to the slide rail 504, and the bracket 507 is slidably connected to the slide rail 504.

[0053] Through the above technical solution, the slide rail 504 limits the bidirectional screw 506 and the bracket 507, so that the rotation of the bidirectional screw 506 can drive the two brackets 507 to move toward or in opposite directions.

[0054] See also Figure 6 The bracket 507 is located at the front end of the electric clamp 508 and is slidably connected to a limit plate 517. The front end of the limit plate 517 is rotatably connected to a screw rod 518, and the front end of the screw rod 518 is fixedly connected to a knob 519.

[0055] Through the above technical solution, by rotating the knob 519, the knob 519 drives the screw 1 518 to rotate, and the screw 1 518 is threadedly connected to the bracket 507, thereby controlling the extension and retraction of the screw 1 518. The screw 1 518 drives the limiting plate 517 to move back and forth, which limits the electric clamp 508 and adjusts the moving range, making it easy to adjust according to the thickness of the sandwich panel.

[0056] Example 3

[0057] The following is a specific implementation method of the sandwich panel installation method.

[0058] See also Figure 1-7 ,The installation method of the sandwich panel comprises the following steps;

[0059] S1: Use a milling cutter to mill grooves and open holes in the plate;

[0060] S2: Fix the middle layer 1 and knock the connector 4 into the hole groove of the middle layer 1;

[0061] S3: Connect the top layer 2 and the bottom layer 3 from both ends of the middle layer 1 through the connecting pieces 4 respectively.

[0062] Specifically, during S3 , a resin adhesive may be placed between the middle layer 1 and the top layer 2 , and between the middle layer 1 and the bottom layer 3 .

[0063] Through the above technical solution, the middle layer board 1 is staggered on both sides to punch connection holes, and the top layer board 2 and the bottom layer board 3 are milled with a milling cutter at the corresponding hole positions.

Claims

1. A processing device for preparing a sandwich board, applied to a sandwich board, the sandwich board comprising an intermediate plate (1), wherein the upper end of the intermediate plate (1) is provided with a top plate (2), the lower end of the intermediate plate (1) is provided with a bottom plate (3), the intermediate plate (1) is provided with a plurality of holes and grooves, the holes and grooves of the intermediate plate (1) are provided with a connecting member (4), the connecting member (4) comprises a cylinder (401), one end of the cylinder (401) is fixedly connected with an arc plug (402), the top plate (2) and the bottom plate (3) are provided with grooves on their facing sides, there are two arc plugs (402), the two arc plugs (402) are elastic blocks, the other top end of the arc plug (402) is set to a cone, the openings of the plurality of holes and grooves on the intermediate plate (1) face in opposite directions, and the invention is characterized in that: The invention comprises a striking device (5), wherein the striking device (5) comprises an electric turntable (501), the lower end of the electric turntable (501) is fixedly connected to an electric push rod (502), the lower end of the electric push rod (502) is fixedly connected to a support plate (503), the lower end of the support plate (503) is fixedly connected to a limit block (511), the front end of the support plate (503) is fixedly connected to a slide rail (504), the left end of the slide rail (504) is fixedly connected to a motor (505), the right end of the motor (505) is fixedly connected to a bidirectional screw (506), the outer surface of the bidirectional screw (506) is threadedly connected to a bracket (507), the inner side of the bracket (507) is slidably connected to four electric clamps (508), a spring (509) is provided between the electric clamp (508) and the bracket (507), and the bracket (507) is provided with an electric striking hammer (510) at the front end of the electric clamp (508).

2. The processing equipment for preparing sandwich panels according to claim 1, characterized in that: The upper end of the electric turntable (501) is fixedly connected to a pillar (6), the lower end of the pillar (6) is provided with a workbench (7), the middle part of the upper end of the workbench (7) is provided with an automatic lifting rod (701), the upper end of the automatic lifting rod (701) is fixedly connected to a clamping block (702), the workbench (7) is provided with a blocking bar (703) located in the middle part of the clamping block (702), both ends of the clamping block (702) are fixedly connected to extension plates (704), and the workbench (7) is fixedly connected to baffles (705) located on opposite sides of the two extension plates (704).

3. The processing equipment for preparing sandwich panels according to claim 1, characterized in that: The limit block (511) is configured as an L-shaped structure. The front end of the limit block (511) is slidably connected to a slide rod (512). The outer surface of the slide rod (512) is sleeved with a second spring (513). The other end of the slide rod (512) is fixedly connected to an extrusion plate (514). The extrusion plate (514) and the limit block (511) are respectively provided with an electromagnet (515) and a magnetic block (516) on opposite sides thereof.

4. The processing equipment for preparing sandwich panels according to claim 1, characterized in that: Both ends of the bidirectional screw (506) are slidably connected to the slide rail (504), and the bracket (507) is slidably connected to the slide rail (504).

5. The processing equipment for preparing sandwich panels according to claim 1, characterized in that: The bracket (507) is located at the front end of the electric clamp (508) and is slidably connected to a limit plate (517). The front end of the limit plate (517) is rotatably connected to a screw rod (518), and the front end of the screw rod (518) is fixedly connected to a knob (519).

6. A method for installing a sandwich panel, applied to a processing device for preparing a sandwich panel according to claim 5, characterized in that: The method includes the following steps: S1: Use a milling cutter to mill grooves and open holes in the plate; S2: Fix the middle layer (1) and use the processing equipment of the sandwich panel to knock the connecting piece (4) into the hole groove of the middle layer (1); S3: Connect the top layer (2) and the bottom layer (3) from both ends of the middle layer (1) through the connecting pieces (4).

7. The method for installing a sandwich panel according to claim 6, characterized in that: During S3 , a resin adhesive may be placed between the middle layer ( 1 ) and the top layer ( 2 ), and between the middle layer ( 1 ) and the bottom layer ( 3 ).

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