A concrete mixing plant

Abstract

The application belongs to the technical field of concrete preparation, and discloses a concrete mixing station, which comprises a material placing platform, a feeding mechanism arranged below the material placing platform, a mixing tank arranged below the feeding mechanism, a top cover arranged at the top of the mixing tank, an inner cavity and an outer cavity formed by a partition plate at the bottom of the top cover, a powder inlet communicated to the inner cavity and arranged at the center of the top cover, a aggregate inlet arranged along the outer cavity of the top cover, and a flow guide inclined plate arranged at the bottom of the outer cavity in a circumferential direction; an inner cavity outlet is arranged at the bottom of the inner cavity, a ring-shaped distributor is rotatably connected to the inner cavity outlet, a water inlet is arranged on the upper side of the mixing tank, an axle hole is arranged at the center of the bottom of the mixing tank, a mixing shaft is sealingly and rotatably connected to the axle hole, the top of the mixing shaft is fixedly connected to the ring-shaped distributor, mixing blades are arranged at the middle and lower parts of the mixing shaft in the mixing tank, the bottom of the mixing shaft is fixedly connected to the output end of a mixing motor, and a concrete outlet is arranged on one side of the bottom of the mixing tank. The above can realize uniform and efficient mixing of raw materials.

Description

Technical Field

[0001] This invention relates to the field of concrete preparation, and more specifically to a concrete mixing plant. Background Technology

[0002] Currently, concrete mixing plants are key equipment for producing high-quality concrete. They typically include a material feeding platform, aggregate hoppers, and a mixing tank. During operation, aggregates are fed into the mixing tank from the aggregate hopper through the discharge pipe, while powder and water are added from their respective inlets. Under the action of the mixing blades, they are mixed into concrete.

[0003] However, existing mixing plants have significant shortcomings in material distribution and mixing. Firstly, in the material distribution stage, traditional aggregate inlets are mostly located on the outer top of the mixing tank, with the aggregate naturally accumulating at the tank edge after falling vertically; powder inlets are mostly located in the center of the tank, with the powder concentrating in the central area after falling vertically. This feeding method results in a non-ideal initial material distribution with a clear distinction between the inside and outside, lacking pre-mixing and dispersion of aggregates and powders. Furthermore, the powder easily forms clumps under vertical impact, increasing the difficulty of subsequent mixing. Simultaneously, due to the impact and accumulation, the powder tends to adhere to the inner wall in the central area, leading to poor material flow and material waste.

[0004] Secondly, in the mixing stage, conventional mixing blades are mostly straight or have a simple spiral structure. Their mixing effect is mainly concentrated on circumferential shearing and tumbling, with weak radial convection exchange of materials within the tank. It is difficult to achieve efficient alternating mixing of materials in the inner and outer rings, easily creating inefficient mixing zones. Simultaneously, due to insufficient radial convection, powder in the central area easily agglomerates into cement balls upon contact with sprayed water, while the edge aggregates are difficult to fully wet and coat, severely affecting mixing efficiency and concrete homogeneity, often requiring extended mixing time to meet quality requirements. Summary of the Invention

[0005] In view of the above-mentioned defects, the purpose of this invention is to provide a concrete mixing plant that can achieve uniform and efficient mixing of raw materials.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a concrete mixing plant, comprising a material placement platform, a material collection hopper below the material placement platform, a plurality of material collection hopper outlets at the bottom of the material collection hopper, and a guide rail frame corresponding to each of the material collection hopper outlets. The guide rail frame is fixedly connected at both ends to the support frame of the material placement platform. A hanger that can reciprocate along the guide rail frame is slidably mounted on the guide rail frame. The hanger is frame-type and has a feeding mechanism fixedly connected inside it. The feeding mechanism includes a vertically arranged discharge pipe, the bottom end of which is sealed and fixedly connected to a bend. A mixing tank is located below the feeding mechanism. A top cover is provided on the top of the mixing tank. The bottom of the top cover is divided into an inner cavity and an outer cavity by a funnel-shaped partition that is wider at the top and narrower at the bottom. A powder inlet is provided at the center of the top cover, connecting to the inner cavity. A plurality of aggregate inlets are provided along the outer cavity of the top cover. The bottom of the outer cavity is circumferentially... Multiple guide plates are provided, with their lower ends extending inclined towards the edge of the mixing tank. A vertical inner cavity outlet is located at the bottom of the inner cavity, and an annular distributor is rotatably connected to the outlet. The annular distributor includes a circular distribution plate, the periphery of which is tightly fitted to the inner cavity outlet. A material distribution cone is located at the center of the top of the distribution plate, and several circular discharge holes are formed on the plate. Several water inlets are located on the upper side of the mixing tank, and a shaft hole is located at the center of the bottom of the mixing tank. A stirring shaft is rotatably and sealingly connected to the shaft hole. The top of the stirring shaft is fixedly connected to the lower part of the annular distributor. Stirring blades, S-shaped, are located on the stirring shaft in the lower-middle part of the mixing tank. The bottom part of the stirring shaft outside the mixing tank is fixedly connected to the output end of a stirring motor. A concrete outlet is located on one side of the bottom of the mixing tank.

[0007] As a further improvement of the present invention, an adjusting cylinder is provided on one side of the outer wall of the bend, the top of the cylinder body of the adjusting cylinder is fixed to the outer wall of the bend, and hoppers are hinged on both sides of the lower section of the bend. A hinge seat is provided on the outer side of the back plate of the hopper away from the discharge opening, and the hinge seat is hinged to the bottom end of the piston rod of the adjusting cylinder.

[0008] As a further improvement of the present invention, the water inlet extends inward with a water inlet pipe, the water inlet pipe being bent and its bottom being directly opposite the junction of aggregate and powder in the mixing tank.

[0009] As a further improvement of the present invention, the side of the stirring blade closest to the stirring shaft is the powder side, which is arranged in an arc shape facing the direction of rotation, and the side of the stirring blade away from the stirring shaft is the aggregate side, which is arranged in an arc shape facing away from the direction of rotation.

[0010] As a further improvement of the present invention, a plurality of powder discharge grooves are formed on the arc-shaped surface of the powder side of the stirring blade near the aggregate side. The arc-shaped surface of the powder discharge grooves is arranged in an arc shape facing away from the direction of rotation. The width of the powder discharge grooves gradually decreases from the outside of the stirring axis. A plurality of aggregate discharge grooves are formed on the arc-shaped surface of the aggregate side of the stirring blade near the powder side. The arc-shaped surface of the aggregate discharge grooves is arranged in an arc shape facing the direction of rotation. The width of the aggregate discharge grooves gradually decreases from the outside towards the stirring axis.

[0011] As a further improvement of the present invention, the mixing tank is a hollow cylindrical structure with a conical cavity at the bottom. The upper part of the mixing tank is fixedly connected to a main feeding pipe. The inner wall of the conical cavity is abutted against a stirring blade fixedly connected to a central pipe. The lower end of the mixing tank is fixedly connected to a discharge pipe, and the discharge pipe is fixedly connected to a second electric gate valve.

[0012] As a further improvement of the present invention, the inner wall of the cavity is fully covered with a powder-repellent bonding plate.

[0013] As a further improvement of the present invention, the angle between the inclination of the guide plate and the horizontal plane is controlled between 30° and 60°, and a gap is left between adjacent guide plates to allow aggregate to pass through.

[0014] As a further improvement of the present invention, the discharge hole includes an outer ring discharge hole and an inner ring discharge hole. A plurality of the discharge holes located on the outer ring are inclined toward the inward side, and a plurality of the discharge holes located on the inner ring are inclined toward the outward side. The inclination angle of the discharge hole and the angle between the discharge hole and the vertical plane are controlled between 15° and 30°.

[0015] The beneficial effects of this invention are: 1. By setting circumferentially distributed aggregate inlets in the outer cavity at the top of the mixing tank and configuring guide ramps at the bottom of the outer cavity, the aggregate is initially diverted along the annular channel before entering the tank and falls into the edge area of ​​the tank in a downward throwing motion. This solves the problem of one-sided aggregate accumulation caused by traditional vertical feeding and achieves a uniform initial distribution of aggregate at the edge of the tank, laying the material foundation for subsequent radial mixing with powder. After the powder is impacted and spread by the distribution cone in the center of the inner cavity, the differentiated inclined setting of the inner and outer ring discharge holes on the uniform distribution plate causes the inner layer of powder to be thrown outward and the outer layer of powder to converge inward, forming a secondary impact collision between the two material flows. This structure actively implements physical dispersal during the powder settling stage, eliminating dense clumps formed by the free fall impact of powder during feeding. At the same time, the powder-dispersing and bonding plate covering the inner cavity wall reduces powder adhesion and ensures smooth powder feeding.

[0016] 2. The mixing blades adopt an S-shaped structure, with the powder side curved towards the direction of rotation. This, combined with the powder discharge troughs that gradually narrow radially away from the direction of rotation, forces the central powder to be squeezed and pushed towards the edge aggregate layer. Conversely, the aggregate side curved away from the direction of rotation, combined with the aggregate discharge troughs that gradually narrow radially towards the direction of rotation, forces the edge aggregate to flow back towards the central powder layer. This synergistic effect creates a three-dimensional, radially circulating convection system within the tank, fundamentally solving the problem of insufficient radial exchange capacity in conventional mixing blades. This significantly reduces inefficient mixing zones, effectively prevents the formation of cement balls, and allows the microscopic homogeneity of the concrete to reach the standard within a shorter mixing cycle. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of a concrete mixing plant according to the present invention; Figure 2 for Figure 1 Enlarged diagram of section A in the middle; Figure 3 This is a schematic diagram of the internal structure of the mixing tank in this invention; Figure 4 for Figure 3 Enlarged schematic diagram of section B in the middle; Figure 5 This is an isometric schematic diagram of the stirring blade in this invention; Figure 6 This is a schematic diagram of the stirring blade in this invention.

[0018] In the diagram: 1-Material placement platform, 2-Collection hopper, 3-Collection hopper outlet, 4-Guide rail frame, 5-Hanger, 6-Feeding mechanism, 601-Discharge pipe, 602-Bend, 603-Collection hopper, 604-Hinge seat, 605-Adjusting cylinder, 7-Mixing tank, 701-Top cover, 702-Aggregate inlet, 703-Powder inlet, 704-Guide inclined plate, 705-Mixing shaft, 706 - Mixing motor, 707- Seat leg, 708- Mixing blade, 7081- Powder side, 7082- Powder external discharge trough, 7083- Aggregate side, 7084- Aggregate internal discharge trough, 709- Partition plate, 710- Powder dispersing and stacking plate, 711- Discharge hole, 712- Inner cavity, 713- Distributing cone, 714- Uniform distribution plate, 715- Outer cavity, 716- Concrete outlet, 717- Water inlet pipe. Detailed Implementation

[0019] Please see Figure 1-6A concrete mixing plant includes a material placement platform 1, a material collection hopper 2 located below the material placement platform 1, a plurality of material collection hopper outlets 3 located at the bottom of the material collection hopper 2, and a guide rail frame 4 corresponding to each material collection hopper outlet 3. The two ends of the guide rail frame 4 are fixedly connected to the support frame of the material placement platform 1. The guide rail frame 4 is slidably equipped with a hanger 5 that can move back and forth along it. The hanger 5 is a frame type and a feeding mechanism 6 is fixedly connected inside it.

[0020] The feeding device includes a vertically arranged discharge pipe 601, the bottom end of which is sealed and fixedly connected to a bend 602. An adjusting cylinder 605 is provided on one side of the outer wall of the bend 602, and the top of the cylinder body of the adjusting cylinder 605 is fixed to the outer wall of the bend 602. Hoppers 603 are hinged to both sides of the lower section of the bend 602. A hinge seat 604 is provided on the outer side of the back plate of the hopper 603 away from the discharge opening. The hinge seat 604 is hinged to the bottom end of the piston rod of the adjusting cylinder 605.

[0021] A mixing tank 7 is located at the bottom of the feeding device, and a top cover 701 is located at the top of the mixing tank 7. The bottom of the top cover 701 is divided into an inner cavity 712 and an outer cavity 715 by a funnel-shaped baffle 709 that is wider at the top and narrower at the bottom. Several aggregate inlets 702 are opened at the top of the mixing tank 7 along the outer cavity 715, and the aggregate inlets 702 are evenly arranged around the top of the cover. Several guide plates 704 are arranged around the bottom of the outer cavity 715, and the lower end of the guide plates 704 extends inclined towards the edge of the mixing tank 7. The angle of inclination of the guide plates 704 with the horizontal plane is controlled between 30° and 60°, and gaps are left between adjacent guide plates 704 to allow aggregate to pass through.

[0022] As a further explanation of this embodiment, after the aggregate enters the outer cavity 715 from the circumferential aggregate inlet 702, it flows downward along the annular channel of the outer cavity 715. When it reaches the bottom of the aggregate cavity, the aggregate enters the edge area of ​​the mixing tank 7 in a downward throwing motion under the guidance of the guide plate 704.

[0023] A powder inlet 703 is located at the center of the top cover 701, connecting to the inner cavity 712. The inner wall of the inner cavity 712 is fully covered with a powder-repellent bonding plate 710, which is made of polytetrafluoroethylene coated plate, superhydrophobic nano-coated plate, or smooth PE plate. A vertically positioned outlet is located at the bottom of the inner cavity 712, and an annular distributor is rotatably connected to the outlet. The annular distributor includes a circular distribution plate 714, which is tightly fitted around the outlet of the inner cavity 712. A distributing cone 713 is located at the center of the top of the distribution plate 714, and the distributing cone 713 is vertically upward-pointing. The uniformly distributed plate 714 has several rings of discharge holes 711. The discharge holes 711 in the outer ring are inclined inward, and the discharge holes 711 in the inner ring are inclined outward. The inclination angle of the discharge holes 711 and the angle between the vertical plane are controlled between 15° and 30°.

[0024] As a further explanation of this embodiment, after the powder enters the inner cavity 712 through the central feed port, it first impacts the top of the distribution cone 713 and spreads evenly along the cone surface to form a thin layer of material flow around the cone surface; the thin layer of material flow reaches the lower distribution plate and falls vertically through the distribution holes evenly distributed around the circumference of the plate; during the falling stage, the inner layer of powder is thrown outward and the outer layer of powder converges inward, and the two material flows collide twice, causing the powder clumps to be further broken up and refined, and then continue to sink downward.

[0025] Several water inlets are provided on the upper side of the mixing tank 7. Water inlet pipes 717 extend inward from the water inlets. The water inlet pipes 717 are bent and the bottom of the water inlet pipes 717 is directly opposite the junction of aggregates and powders inside the mixing tank 7.

[0026] A shaft hole is provided at the center of the bottom of the mixing tank 7, and a stirring shaft 705 is rotatably connected to the shaft hole. The top of the stirring shaft 705 is fixedly connected to the bottom of the annular distributor. A stirring blade 708 is located in the lower middle part of the mixing tank 7, on the stirring shaft 705. The stirring blade 708 is shaped similarly to an "S". The side of the stirring blade 708 closest to the stirring shaft 705 is the powder side 7081, which is arc-shaped facing the direction of rotation. The side of the stirring blade 708 furthest from the stirring shaft 705 is the aggregate side 7083, which is arc-shaped facing away from the direction of rotation.

[0027] Several powder discharge grooves 7082 are formed on the arc-shaped surface of the powder side 7081 of the stirring blade 708 near the aggregate side 7083. The arc-shaped surface of the powder discharge grooves 7082 is oriented in the opposite direction of rotation. The width of the powder discharge grooves 7082 gradually decreases from the stirring shaft 705 towards the outer side. Several aggregate discharge grooves 7084 are formed on the arc-shaped surface of the aggregate side 7083 of the stirring blade 708 near the powder side 7081. The arc-shaped surface of the aggregate discharge grooves 7084 is oriented in the arc-shaped direction of rotation. The width of the aggregate discharge grooves 7084 gradually decreases from the outer side towards the stirring shaft 705.

[0028] The bottom portion of the mixing shaft 705, located outside the mixing tank 7, is fixedly connected to the output end of the mixing motor 706. Support legs 707 are fixedly connected to both sides of the bottom of the mixing tank 7. A concrete outlet 716 is provided on one side of the bottom of the mixing tank 7.

[0029] The working principle and usage process of this embodiment are as follows: After loading, the aggregate falls from the material placement platform 1 to the collection hopper 2 below for temporary storage. According to the production command, the hanger 5 at the outlet 3 of the collection hopper slides horizontally along the guide rail 4, precisely moving the feeding mechanism 6 below to directly above the powder inlet 703 of the mixing tank 7. The feeding mechanism 6 is activated, and the powder enters the curved pipe 602 through the vertical discharge pipe 601, falling from the end of the curved pipe 602 into the hopper 603. At this time, the piston rod of the adjusting cylinder 605 extends and retracts, pulling the hopper 603 to rotate around the hinge point, smoothly unloading the powder.

[0030] Powder falls vertically into the inner cavity 712 from the powder inlet 703 at the center of the top cover 701. The powder first impacts the top of the distribution cone 713 at high speed, spreading evenly along the cone surface to form a thin layer of material flowing around it. This thin layer falls onto the distribution plate 714. Due to the outward tilt of the inner ring discharge hole 711 and the inward tilt of the outer ring discharge hole 711, the inner layer of powder is thrown outward while the outer layer converges inward. The two streams collide twice below the distribution plate 714, further breaking up and refining the powder clumps. The broken-up powder continues to settle downwards, falling into the lower middle area of ​​the mixing tank 7, forming an inner and outer partition with the aggregate at the edge. The powder-retaining bonding plate made of polytetrafluoroethylene or similar materials on the inner wall of the inner cavity 712 effectively prevents powder from sticking to the wall and clogging. Aggregate enters the outer cavity 715 from several aggregate inlets 702 evenly distributed circumferentially at the top of the mixing tank 7. The aggregate flows downward along the annular channel of the outer cavity 715. When it reaches the bottom, it is thrown into the edge area of ​​the mixing tank 7 by the guide plate 704 in a downward throwing motion.

[0031] As the aggregates and powder fall, the water inlet on the upper side of the mixing tank 7 is activated. Water is sprayed directionally through the internally bendable water inlet pipe 717, with its outlet directly facing the junction of the aggregates and powder inside the mixing tank 7. The high-pressure water flow wets the materials at the initial contact stage, preventing dust generation and providing immediate moisture for the subsequent cement hydration reaction.

[0032] The stirring motor 706 drives the stirring shaft 705 to rotate, which in turn drives the specially designed S-shaped stirring blades 708. The powder is pushed outwards, with the powder side 7081 of the stirring blades 708 closest to the shaft facing away from the direction of rotation. As the blades rotate, this arcuate surface pushes the powder in the center towards the edge of the tank. The powder outward discharge channel 7082 gradually decreases in width from the shaft center outwards, compressing and accelerating the shearing of the powder, forcing it to diffuse outwards through the aggregate layer. The aggregate flows inwards, with the aggregate side 7083 of the stirring blades 708 away from the shaft center, its arcuate surface facing the direction of rotation. This arcuate surface pushes the aggregate at the edge towards the center of the tank. The aggregate inward discharge channel 7084 gradually decreases in width from the outside towards the shaft center, compressing and decelerating the aggregate, forcing it to flow inwards through the powder layer.

[0033] Under the forced action of the blades, a circulating convection of central powder and edge aggregate is formed inside the tank. The two streams of material converge and collide violently in the lower part of the mixing tank 7, and in conjunction with the hydration reaction, the aggregate, powder and water are mixed into a uniform, high-quality concrete mixture in a very short time, which is finally discharged from the concrete outlet 716 at the bottom of the mixing tank 7.

Claims

1. A concrete mixing plant, characterized in that, Includes a material placement platform (1), with a material collection hopper (2) below the material placement platform (1). The bottom of the material collection hopper (2) has several material collection hopper outlets (3), each of which is correspondingly equipped with a guide rail frame (4). Both ends of the guide rail frame (4) are fixedly connected to the support frame of the material placement platform (1). The guide rail frame (4) is slidably fitted with a hanger (5) that can reciprocate along it. The hanger (5) is a frame type and has a feeding mechanism (6) fixedly connected inside it. The feeding mechanism (6) includes a vertically arranged discharge pipe (601). 601) The bottom end is sealed and fixedly connected to the bend (602). A mixing tank (7) is provided below the feeding mechanism (6). A top cover (701) is provided on the top of the mixing tank (7). The bottom of the top cover (701) is divided into an inner cavity (712) and an outer cavity (715) by a funnel-shaped partition (709) that is wider at the top and narrower at the bottom. A powder inlet (703) is provided at the center of the top cover (701). The powder inlet (703) is connected to the inner cavity (712). Several aggregate inlets (702) are provided along the outer cavity (715) of the top cover (701). The bottom of the outer cavity (715) is along Multiple guide plates (704) are arranged circumferentially, and the lower ends of the guide plates (704) extend inclinedly towards the edge of the mixing tank (7); a vertical inner cavity outlet is provided at the bottom of the inner cavity (712), and an annular distributor is rotatably connected to the inner cavity outlet. The annular distributor includes a circular distribution plate (714), the periphery of which is tightly fitted to the inner cavity outlet. A distribution cone (713) is provided at the center of the top of the distribution plate (714), and several rings of discharge holes (711) are opened on the distribution plate (714); the upper side of the mixing tank (7) is provided with The mixing tank (7) has several water inlets. A shaft hole is provided at the center of the bottom of the mixing tank (7). A mixing shaft (705) is rotatably connected to the shaft hole. The top of the mixing shaft (705) is fixedly connected to the bottom of the annular distributor. A mixing blade (708) is provided in the lower middle part of the mixing shaft (7). The mixing blade (708) is S-shaped. The bottom part of the mixing shaft (705) outside the mixing tank (7) is fixedly connected to the output end of the mixing motor (706). A concrete outlet (716) is provided on one side of the bottom of the mixing tank (7).

2. A concrete mixing plant according to claim 1, characterized in that, An adjusting cylinder (605) is provided on one side of the outer wall of the bend (602). The top of the cylinder body of the adjusting cylinder (605) is fixed to the outer wall of the bend (602). A hopper (603) is hinged to both sides of the lower section of the bend (602). A hinge seat (604) is provided on the outer side of the back plate of the hopper (603) away from the discharge opening. The hinge seat (604) is hinged to the bottom end of the piston rod of the adjusting cylinder (605).

3. A concrete mixing plant according to claim 1, characterized in that, The inlet extends inward with an inlet pipe (717), which is bent and its bottom is directly opposite the junction of aggregate and powder in the mixing tank (7).

4. A concrete mixing plant according to claim 1, characterized in that, The side of the stirring blade (708) closest to the stirring shaft (705) is the powder side (7081), which is arc-shaped on the side facing the direction of rotation. The side of the stirring blade (708) away from the stirring shaft (705) is the aggregate side (7083), which is arc-shaped on the side facing away from the direction of rotation.

5. A concrete mixing plant according to claim 4, characterized in that, On the powder side (7081) of the stirring blade (708), near the aggregate side (7083), a plurality of powder discharge grooves (7082) are provided. The arc-shaped surface of the powder discharge grooves (7082) is arranged in an arc shape facing away from the direction of rotation. The width of the powder discharge grooves (7082) gradually decreases from the stirring shaft (705) to the outside. On the aggregate side (7083) of the stirring blade (708), near the powder side (7081), a plurality of aggregate discharge grooves (7084) are provided. The arc-shaped surface of the aggregate discharge grooves (7084) is arranged in an arc shape facing the direction of rotation. The width of the aggregate discharge grooves (7084) gradually decreases from the outside to the stirring shaft (705).

6. A concrete mixing plant according to claim 1, characterized in that, The mixing tank (1) is a hollow cylindrical structure with a conical cavity at the bottom. The upper part of the mixing tank (1) is fixedly connected to the main feeding pipe (28). The inner wall of the conical cavity is abutted by a stirring plate (12) fixedly connected to the central pipe (8). The lower end of the mixing tank (1) is fixedly connected to the discharge pipe (29). The discharge pipe (29) is fixedly connected to the second electric gate valve (30).

7. A concrete mixing plant according to claim 1, characterized in that, The inner wall of the inner cavity (712) is fully covered with a powder-repellent bonding plate.

8. A concrete mixing plant according to claim 1, characterized in that, The angle between the inclination of the guide plate (704) and the horizontal plane is controlled between 30° and 60°, and a gap is left between adjacent guide plates (704) to allow aggregate to pass through.

9. A concrete mixing plant according to claim 1, characterized in that, The discharge hole (711) includes an outer ring discharge hole and an inner ring discharge hole. The discharge holes (711) located on the outer ring are inclined inward, and the discharge holes (711) located on the inner ring are inclined outward. The inclination angle of the discharge hole (711) and the vertical plane are controlled between 15° and 30°.

Images