CN221498204U - Rear floor structure, casting mold - Google Patents

Abstract

The utility model discloses a rear floor structure and a casting mold, wherein the rear floor structure comprises: the integrated cast rear floor body and the rear floor frame comprise a left longitudinal beam, a right longitudinal beam and a beam group, wherein the beam group comprises at least two beams, the beams are connected between the left longitudinal beam and the right longitudinal beam, the longitudinal beam and/or the beams are provided with first grooves with downward openings, and a plurality of reinforcing ribs are arranged in the first grooves. The integral casting molding process is adopted to manufacture the rear floor structure, so that the self weight of the rear floor structure can be effectively reduced, the overall performance of the rear floor structure is optimized, the production cost of the rear floor structure is reduced, and the production efficiency is improved; through set up the first recess of opening decurrent on longeron and/or crossbeam, can effectively promote holistic bending rigidity and the structural strength of back floor structure, simultaneously, reduce back floor structure's casting degree of difficulty and cost.

Description

Rear floor structure, casting mold

Technical Field

The utility model relates to the field of vehicle body structures, in particular to a rear floor structure and a casting mold.

Background Art

At present, the traditional rear floor structure of the vehicle body is generally manufactured by stamping sheet metal technology or one-piece die-casting technology. Among them, the rear floor manufactured by stamping sheet metal technology has the problems of heavy weight, low connection strength between parts, large production area, high manufacturing equipment cost, many parts, complex assembly, large cumulative tolerance, etc.; the rear floor manufactured by the existing one-piece die-casting technology has the problems of low bending and torsional stiffness, low stiffness of the installation point, large number of manufacturing molds, complex mold structure and difficulty in sealing the mold cavity.

Utility Model Content

The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the utility model proposes a rear floor structure that can solve the problems of heavy weight, complex assembly, large tolerance, etc., and also has the advantages of high bending and torsional rigidity, high rigidity at the installation point, small number of molds used, and simple structure.

According to the embodiment of the utility model, the rear floor structure includes: an integrally cast rear floor body and a rear floor frame, the rear floor frame includes a left longitudinal beam, a right longitudinal beam and a cross beam group, the cross beam group includes at least two cross beams, the cross beams are connected between the left longitudinal beam and the right longitudinal beam, and at least one of the left longitudinal beam, the right longitudinal beam and the cross beam group has a first groove opening downward, and a plurality of reinforcing ribs are arranged in the first groove.

According to the rear floor structure of the embodiment of the utility model, the rear floor structure is manufactured by an integrated casting molding process, which can effectively reduce the weight of the rear floor structure itself, optimize the overall performance of the rear floor structure, reduce the production cost of the rear floor structure, and improve production efficiency; by providing a first groove with an opening downward on the longitudinal beam and/or the transverse beam, the overall bending and torsional rigidity and structural strength of the rear floor structure can be effectively improved, and at the same time, the casting difficulty and cost of the rear floor structure can be reduced.

In addition, the rear floor structure according to the utility model may also have the following additional technical features:

In some embodiments, the crossbeam group includes a front crossbeam adjacent to the front side of the rear floor body, a rear crossbeam adjacent to the rear side of the rear floor body, and at least one intermediate crossbeam, wherein in the front-to-back direction, the intermediate crossbeam is located between the front crossbeam and the rear crossbeam, wherein the reinforcing ribs of the front crossbeam, the reinforcing ribs of the rear crossbeam, and the reinforcing ribs of the intermediate crossbeam all extend in a zigzag manner along the left-right direction.

In some embodiments, the left end of the middle cross beam has a first intersection with the left longitudinal beam, the right end of the middle cross beam has a second intersection with the right longitudinal beam, the left end of the rear cross beam has a third intersection with the left longitudinal beam, and the right end of the rear cross beam has a fourth intersection with the right longitudinal beam, the first intersection and the second intersection respectively have a sub-frame left front mounting seat and a sub-frame right front mounting seat that are integrally cast with the rear floor frame, and the third intersection and the fourth intersection respectively have a sub-frame left rear mounting seat and a sub-frame right rear mounting seat that are integrally cast with the rear floor frame.

In some embodiments, the rear floor structure also includes a left rear shock absorber mounting seat and a right rear shock absorber mounting seat integrally cast with the rear floor frame, the left rear shock absorber mounting seat is located between the left front mounting seat of the subframe and the left rear mounting seat of the subframe on the left longitudinal beam, and the right rear shock absorber mounting seat is located between the right front mounting seat of the subframe and the right rear mounting seat of the subframe on the right longitudinal beam.

In some embodiments, the left front mounting seat of the subframe, the right front mounting seat of the subframe, the left rear mounting seat of the subframe, the right rear mounting seat of the subframe, the left rear shock absorber mounting seat and the right rear shock absorber mounting seat all have a second groove opening upward, and the second groove has radially distributed reinforcing ribs.

In some embodiments, the reinforcing ribs of the left longitudinal beam and the reinforcing ribs of the right longitudinal beam each include a first reinforcing rib extending in a zigzag manner along the front-to-back direction, a second reinforcing rib extending in a zigzag manner along the front-to-back direction, and a third reinforcing rib extending in a straight line along the front-to-back direction, wherein the first reinforcing rib and the second reinforcing rib have a plurality of reinforcing rib intersections in the front-to-back direction, and the third reinforcing rib sequentially connects two adjacent reinforcing rib intersections in the front-to-back direction.

In some embodiments, the rear floor structure further includes a left rear wheel cover and a right rear wheel cover integrally cast with the rear floor body.

In some embodiments, the left side surface of the left longitudinal beam is a plane, and the lower end of the left rear wheel cover is connected to the left side surface of the left longitudinal beam; the right side surface of the right longitudinal beam is a plane, and the lower end of the right rear wheel cover is connected to the right side surface of the right longitudinal beam.

In some embodiments, the angle between the left side surface of the left longitudinal beam and the horizontal plane is a, and the angle between the right side surface of the right longitudinal beam and the horizontal plane is b, satisfying: 85°≤a＜90°, 85°≤b＜90°.

In some embodiments, the side surface of the left rear wheel cover facing the right side has a plurality of first inner reinforcing ribs extending in the up-down direction, and the lower ends of the first inner reinforcing ribs extend to the rear floor body; the side surface of the right rear wheel cover facing the left side has a plurality of second inner reinforcing ribs extending in the up-down direction, and the lower ends of the second inner reinforcing ribs extend to the rear floor body.

In some embodiments, the rear floor structure is made of aluminum alloy.

The utility model also proposes a casting mold for the rear floor structure of the above embodiment; it includes: a movable mold and a fixed mold, the movable mold can be movably arranged at the upper end of the fixed mold, and a casting space for the rear floor structure is constructed between the movable mold and the fixed mold.

Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic structural diagram of a rear floor structure according to an embodiment of the utility model;

FIG2 is a bottom view of a rear floor structure according to an embodiment of the present utility model;

FIG3 is a partial schematic diagram of a rear floor structure (bottom) according to an embodiment of the present invention;

FIG4 is a top view of a rear floor structure according to an embodiment of the present utility model;

FIG5 is a first partial schematic diagram of a rear floor structure (upper portion) according to an embodiment of the present invention;

FIG6 is a second partial schematic diagram of the rear floor structure (upper part) according to an embodiment of the present invention;

7 is a cross-sectional view (left-right direction) of the rear floor structure according to an embodiment of the present utility model;

8 is a cross-sectional view (front-rear direction) of the rear floor structure according to an embodiment of the present invention;

9 is a partial cross-sectional view of the right rear shock absorber mounting seat of the rear floor structure according to an embodiment of the utility model;

10 is a partial cross-sectional view of the right front mounting seat of the sub-frame of the rear floor structure according to an embodiment of the present utility model.

Reference numerals:

100. Rear floor structure;

1. Rear floor body;

2. Rear floor frame; 21. Left longitudinal beam; 22. Right longitudinal beam; 23. Cross beam assembly; 24. Left front mounting seat of subframe; 25. Right front mounting seat of subframe; 26. Left rear mounting seat of subframe; 27. Right rear mounting seat of subframe; 28. Left rear shock absorber mounting seat; 29. Right rear shock absorber mounting seat; 231. Front cross beam; 232. Rear cross beam; 233. Middle cross beam;

3. First groove; 4. Second groove;

5. Left rear wheel cover; 51. First inner reinforcing rib;

6. Right rear wheel cover; 61. Second inner reinforcement rib.

DETAILED DESCRIPTION

The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

A rear floor structure 100 according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 10 .

As shown in Figures 1 to 10, the rear floor structure 100 according to the embodiment of the utility model includes: an integrally cast rear floor body 1 and a rear floor frame 2, the rear floor frame 2 includes a left longitudinal beam 21, a right longitudinal beam 22 and a cross beam group 23, the cross beam group 23 includes at least two cross beams, the cross beams are connected between the left longitudinal beam 21 and the right longitudinal beam 22, at least one of the left longitudinal beam, the right longitudinal beam and the cross beam group has a first groove 3 opening downward, and a plurality of reinforcing ribs are arranged in the first groove 3.

In the present embodiment, the rear floor structure 100 formed by integral casting has the characteristic of being light in weight and can well meet the requirements of lightweight design. At the same time, since the rear floor structure 100 is formed by integral casting, there are no problems such as many parts, complex assembly, large cumulative tolerances, and low overall structural strength and bending strength in the existing stamping sheet metal process for manufacturing the rear floor structure 100. In addition, the integral casting process does not require a large number of molds, fixtures, and gauges, etc., thereby reducing the cost of manufacturing equipment and management costs, effectively reducing production costs, improving production efficiency, and reducing production floor space.

In this embodiment, the longitudinal beam may have the first groove 3 opening downward, or the cross beam may have the first groove 3 opening downward, or both the longitudinal beam and the cross beam may have the first groove 3 opening downward. Since the rear floor structure 100 as a whole mainly bears the force in the up-down direction of the whole vehicle, compared with the existing one-piece cast rear floor structure 100, the design of the first groove 3 can effectively improve the bending and torsional rigidity and support of the rear floor structure 100 in the up-down direction of the whole vehicle. At the same time, a plurality of reinforcing ribs are arranged in the first groove 3, which can further improve the structural strength and rigidity of the longitudinal beam and the cross beam, thereby improving the NVH performance of the whole vehicle, so that the overall performance of the rear floor structure 100 is further improved.

In some embodiments, during the one-piece die-casting process, the design of the first groove 3 can reduce the diversion of the molten metal filled in the mold during the flow process, thereby improving the filling capacity of the molten metal in the die-casting mold, so that the mechanical properties of the cast rear floor structure 100 are significantly improved, thereby ensuring the production quality of the rear floor structure 100.

The longitudinal beams and cross beams of the rear floor structure cast by the existing one-piece casting process mostly have "C"-shaped grooves opening toward the left and right sides of the vehicle, which will increase the diversion of the molten metal during the flow. At the same time, in order to cast the "C"-shaped grooves, a separate casting mold needs to be designed, which not only increases the casting difficulty but also increases the casting cost. The structural design of the rear floor of this embodiment is achieved by designing a first groove 3 opening downward on the longitudinal beam and the cross beam, which not only can reduce the diversion of the molten metal during the flow, but also does not require the additional design of a casting mold, thereby reducing the number of molds and reducing the casting difficulty and cost.

According to the rear floor structure 100 of the embodiment of the utility model, the rear floor structure 100 formed by integral casting can effectively reduce its own weight, optimize the overall performance of the rear floor structure 100, reduce the production cost of the rear floor structure 100, and improve the production efficiency; by providing the first groove 3 with the opening downward on the longitudinal beam and/or the cross beam, the overall bending and torsional rigidity and structural strength of the rear floor structure 100 can be effectively improved, and at the same time, the casting difficulty and cost of the rear floor structure 100 can be reduced.

In one embodiment of the utility model, as shown in FIGS. 1 to 10 , the cross beam group 23 includes a front cross beam 231 adjacent to the front side of the rear floor body 1, a rear cross beam 232 adjacent to the rear side of the rear floor body 1, and at least one intermediate cross beam 233. In the front-to-back direction, the intermediate cross beam 233 is located between the front cross beam 231 and the rear cross beam 232, wherein the reinforcing ribs of the front cross beam 231, the rear cross beam 232, and the intermediate cross beam 233 all extend in a broken line along the left-right direction. For example, as shown in FIG. 2 , in the left-right direction of the vehicle, the reinforcing ribs in the front cross beam 231, the intermediate cross beam 233, and the rear cross beam 232 all extend in a broken line. Such a design can not only strengthen the overall structural strength and rigidity of the cross beam group 23, but also improve the overall energy absorption effect of the rear floor structure 100 and improve the overall impact resistance of the rear floor structure 100.

In a specific embodiment of the present utility model, as shown in Figures 1 to 10, the left end of the middle cross beam 233 has a first intersection with the left longitudinal beam 21, the right end of the middle cross beam 233 has a second intersection with the right longitudinal beam 22, the left end of the rear cross beam 232 has a third intersection with the left longitudinal beam 21, and the right end of the rear cross beam 232 has a fourth intersection with the right longitudinal beam 22. The first intersection and the second intersection respectively have a sub-frame left front mounting seat 24 and a sub-frame right front mounting seat 25 that are integrally cast with the rear floor frame 2, and the third intersection and the fourth intersection respectively have a sub-frame left rear mounting seat 26 and a sub-frame right rear mounting seat 27 that are integrally cast with the rear floor frame 2.

In this specific embodiment, by arranging the sub-frame mounting seat at the intersection of the cross beam and the longitudinal beam, the structural rigidity of the sub-frame mounting seat can be effectively improved, so that the connection between the sub-frame and the rear floor structure 100 is more solid and reliable. At the same time, by integrally molding and casting the sub-frame mounting seat and the rear floor frame 2, the rear floor frame 2 as a whole can share the force for the sub-frame mounting seat, thereby reducing the load of the sub-frame mounting seat and extending the service life of the sub-frame mounting seat.

In a specific embodiment of the present utility model, as shown in Figures 1 to 10, the rear floor structure 100 also includes a left rear shock absorber mounting seat 28 and a right rear shock absorber mounting seat 29 that are integrally cast with the rear floor frame 2. The left rear shock absorber mounting seat 28 is located between the sub-frame left front mounting seat 24 and the sub-frame left rear mounting seat 26 on the left longitudinal beam 21, and the right rear shock absorber mounting seat 29 is located between the sub-frame right front mounting seat 25 and the sub-frame right rear mounting seat 27 on the right longitudinal beam 22.

In this specific embodiment, by integrally casting the rear shock absorber mounting base and the rear floor frame 2, the structural strength and rigidity of the rear shock absorber mounting base can be effectively improved, thereby significantly enhancing the connection strength between the rear shock absorber and the rear shock absorber mounting base, making connection failure less likely to occur, thereby improving the performance of the entire vehicle.

In a specific embodiment of the present utility model, as shown in Figures 1 to 10, the subframe left front mounting seat 24, the subframe right front mounting seat 25, the subframe left rear mounting seat 26, the subframe right rear mounting seat 27, the left rear shock absorber mounting seat 28 and the right rear shock absorber mounting seat 29 all have a second groove 4 opening upward, and the second groove 4 has radially distributed reinforcing ribs.

The existing integrally cast rear floor structure subframe and rear shock absorber mounting base are both cantilever structures, and only one end connected to the rear floor structure is stressed. Thus, after the vehicle has been running for a long time, the connection between the subframe and the rear shock absorber and the rear floor structure is prone to failure, thus causing a safety accident.

In the present embodiment, the sub-frame mounting seat and the rear shock absorber mounting seat are both provided with a second groove 4 opening upward, and the sub-frame and the rear shock absorber are respectively mounted via the second groove 4, so that the connection strength between the sub-frame and the sub-frame mounting seat, and the connection strength between the rear shock absorber and the rear shock absorber mounting seat can be effectively improved; for example, as shown in FIGS. 9 and 10 , when the sub-frame and the rear shock absorber are respectively mounted on the sub-frame mounting seat and the rear shock absorber mounting seat, both side walls of the second groove 4 can be subjected to force in the left-right direction of the vehicle, so that the connection failure between the sub-frame and the rear shock absorber and their respective mounting seats is not likely to occur, thereby effectively improving the safety performance of the entire vehicle.

In one embodiment of the utility model, as shown in Figures 1 to 10, the reinforcing ribs of the left longitudinal beam 21 and the reinforcing ribs of the right longitudinal beam 22 include a first reinforcing rib extending in a zigzag manner along the front-to-back direction, a second reinforcing rib extending in a zigzag manner along the front-to-back direction, and a third reinforcing rib extending in a straight line along the front-to-back direction, wherein the first reinforcing rib and the second reinforcing rib have a plurality of reinforcing rib intersections in the front-to-back direction, and the third reinforcing rib sequentially connects two adjacent reinforcing rib intersections in the front-to-back direction.

In this embodiment, the first reinforcing rib and the second reinforcing rib extending in a zigzag manner along the front-rear direction of the vehicle, and the third reinforcing rib extending in a straight line along the front-rear direction of the vehicle can effectively improve the structural strength and bending-torsional stiffness of the longitudinal beam, thereby effectively improving the overall structural performance of the rear floor structure 100.

In one embodiment of the present invention, as shown in Figures 1 to 10, the rear floor structure 100 further includes a left rear wheel cover 5 and a right rear wheel cover 6 integrally cast with the rear floor body 1. In this embodiment, by integrally casting the rear wheel cover with the rear floor body 1, the mechanical properties of the rear wheel cover can be effectively improved, thereby effectively improving the overall quality of the rear floor structure 100.

In a specific embodiment of the present invention, as shown in Figures 1 to 10, the left side of the left longitudinal beam 21 is a plane, and the lower end of the left rear wheel cover 5 is connected to the left side of the left longitudinal beam 21; the right side of the right longitudinal beam 22 is a plane, and the lower end of the right rear wheel cover 6 is connected to the right side of the right longitudinal beam 22. For example, as shown in Figure 7, the lower end of the left rear wheel cover 5 is connected to the left side of the left longitudinal beam 21 as a whole, and the lower end of the right rear wheel cover 6 is connected to the right side of the right longitudinal beam 22 as a whole. Such a design can not only reduce the difficulty of integral casting and improve structural performance, but also reduce casting molds, reduce casting costs, and improve casting efficiency.

In a specific embodiment of the present invention, as shown in Figures 1 to 10, the angle between the left side surface of the left longitudinal beam 21 and the horizontal plane is a, and the angle between the right side surface of the right longitudinal beam 22 and the horizontal plane is b, satisfying: 85°≤a＜90°, 85°≤b＜90°. Such a design can effectively reduce the difficulty of demolding and improve product quality.

In a specific embodiment of the utility model, as shown in Figures 1 to 10, the side of the left rear wheel cover 5 facing the right side has a plurality of first inner reinforcing ribs 51 extending in the up-down direction, and the lower ends of the first inner reinforcing ribs 51 extend to the rear floor body 1; the side of the right rear wheel cover 6 facing the left side has a plurality of second inner reinforcing ribs extending in the up-down direction, and the lower ends of the second inner reinforcing ribs extend to the rear floor body 1. In this specific embodiment, the first inner reinforcing ribs 51 and the second inner reinforcing ribs can effectively improve the structural strength and mechanical properties of the rear wheel cover.

In a specific embodiment of the present invention, as shown in FIGS. 1 to 10 , the rear floor structure 100 is made of aluminum alloy. Aluminum alloy has the characteristics of light weight and high structural strength. Using aluminum alloy to manufacture the rear floor structure 100 can effectively reduce the weight of the rear floor structure 100 and improve the structural strength and rigidity of the rear floor structure 100.

The utility model also provides a casting mold for the rear floor structure 100 of the above embodiment;

The casting mold according to the embodiment of the utility model comprises: a movable mold and a fixed mold. The movable mold is movably arranged at the upper end of the fixed mold, and a casting space for the rear floor structure 100 is constructed between the movable mold and the fixed mold.

Compared with the existing one-piece casting mold for manufacturing the rear floor structure, since the longitudinal beam of the rear floor structure 100 in the above embodiment is not designed with a "C"-shaped groove, there is no need to additionally design the corresponding core-pulling slider molds on both sides of the longitudinal beam. In this way, the rear floor structure 100 of the above embodiment does not require four sets of molds, namely, a core-pulling slider mold, a movable mold and a fixed mold, but only two sets of molds, namely, a movable mold and a fixed mold, are required, which effectively reduces the casting difficulty and casting cost and improves the casting efficiency.

Other structures and operations of the rear floor structure 100 and the casting mold according to the embodiment of the present invention are well known to those skilled in the art and will not be described in detail herein.

In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims (12)

1. A rear floor structure, characterized in that it comprises: a rear floor body and a rear floor frame formed by integral casting, the rear floor frame comprises a left longitudinal beam, a right longitudinal beam and a cross beam group, the cross beam group comprises at least two cross beams, the cross beams are connected between the left longitudinal beam and the right longitudinal beam, at least one of the left longitudinal beam, the right longitudinal beam and the cross beam group has a first groove opening downward, and a plurality of reinforcing ribs are arranged in the first groove. 2. The rear floor structure according to claim 1 is characterized in that the crossbeam group includes a front crossbeam adjacent to the front side of the rear floor body, a rear crossbeam adjacent to the rear side of the rear floor body and at least one intermediate crossbeam, and in the front-to-back direction, the intermediate crossbeam is located between the front crossbeam and the rear crossbeam, wherein the reinforcing ribs of the front crossbeam, the reinforcing ribs of the rear crossbeam and the reinforcing ribs of the intermediate crossbeam all extend in a zigzag manner along the left-right direction. 3. The rear floor structure according to claim 2 is characterized in that the left end of the middle cross beam and the left longitudinal beam have a first intersection, the right end of the middle cross beam and the right longitudinal beam have a second intersection, the left end of the rear cross beam and the left longitudinal beam have a third intersection, the right end of the rear cross beam and the right longitudinal beam have a fourth intersection, the first intersection and the second intersection respectively have a sub-frame left front mounting seat and a sub-frame right front mounting seat integrally cast with the rear floor frame, and the third intersection and the fourth intersection respectively have a sub-frame left rear mounting seat and a sub-frame right rear mounting seat integrally cast with the rear floor frame. 4. The rear floor structure according to claim 3 is characterized in that the rear floor structure also includes a left rear shock absorber mounting seat and a right rear shock absorber mounting seat integrally cast with the rear floor frame, the left rear shock absorber mounting seat is located between the left front mounting seat of the subframe and the left rear mounting seat of the subframe on the left longitudinal beam, and the right rear shock absorber mounting seat is located between the right front mounting seat of the subframe and the right rear mounting seat of the subframe on the right longitudinal beam. 5. The rear floor structure according to claim 4 is characterized in that the left front mounting seat of the subframe, the right front mounting seat of the subframe, the left rear mounting seat of the subframe, the right rear mounting seat of the subframe, the left rear shock absorber mounting seat and the right rear shock absorber mounting seat all have a second groove opening upward, and the second groove has radially distributed reinforcing ribs. 6. The rear floor structure according to claim 1 is characterized in that the reinforcing ribs of the left longitudinal beam and the reinforcing ribs of the right longitudinal beam both include a first reinforcing rib extending in a zigzag manner along the front-to-back direction, a second reinforcing rib extending in a zigzag manner along the front-to-back direction, and a third reinforcing rib extending in a straight line along the front-to-back direction, wherein the first reinforcing rib and the second reinforcing rib have a plurality of reinforcing rib intersections in the front-to-back direction, and the third reinforcing rib sequentially connects two adjacent reinforcing rib intersections in the front-to-back direction. 7. The rear floor structure according to claim 1, characterized in that the rear floor structure further comprises a left rear wheel cover and a right rear wheel cover integrally cast with the rear floor body. 8. The rear floor structure according to claim 7, characterized in that: The left side surface of the left longitudinal beam is a plane, and the lower end of the left rear wheel cover is connected to the left side surface of the left longitudinal beam; The right side surface of the right longitudinal beam is a plane, and the lower end of the right rear wheel cover is connected to the right side surface of the right longitudinal beam. 9. The rear floor structure according to claim 8 is characterized in that the angle between the left side surface of the left longitudinal beam and the horizontal plane is a, and the angle between the right side surface of the right longitudinal beam and the horizontal plane is b, satisfying: 85°≤a＜90°, 85°≤b＜90°. 10. The rear floor structure according to claim 7, characterized in that: The side surface of the left rear wheel cover facing the right side has a plurality of first inner reinforcing ribs extending in the up-down direction, and the lower ends of the first inner reinforcing ribs extend to the rear floor body; The side surface of the right rear wheel cover facing the left side has a plurality of second inner reinforcing ribs extending in the up-down direction, and the lower ends of the second inner reinforcing ribs extend to the rear floor body. 11. The rear floor structure according to any one of claims 1 to 10, characterized in that the rear floor structure is made of aluminum alloy. 12. A casting mold for a rear floor structure according to any one of claims 1 to 11, characterized in that it comprises: a movable mold and a fixed mold, wherein the movable mold is movably arranged at the upper end of the fixed mold, and a casting space for the rear floor structure is constructed between the movable mold and the fixed mold.