Inflatable flexible dumbbell and manufacturing method thereof

Abstract

The invention discloses an inflatable flexible dumbbell and a manufacturing method thereof. The inflatable flexible dumbbell comprises a first counterweight part, a second counterweight part and a hard holding part, the first counterweight part comprises a first elastic bag body with a first air cavity; the second counterweight part comprises a second elastic bag body with a second air cavity; the holding part comprises a hard tubular body which is provided with a third air cavity and is made of plastic; the hard tubular body, the first elastic bag body and the second elastic bag body are all made of plastic materials, and fillers are arranged in the first air cavity, the second air cavity and the third air cavity; the hard tubular body, the first elastic bag body and the second elastic bag body are all made of plastic materials, prepared through rotational molding distribution and separated through binding films. The elastic bag body and the gas contained in the elastic bag body avoid the risk that the dumbbell accidentally falls off to hurt people in the using process, the filler is arranged in the gas cavity of the holding part, and on the premise that the weight is equal, the size of the dumbbell is smaller.

Description

Technical Field

[0001] The invention relates to the technical field of dumbbells, in particular to an inflatable flexible dumbbell, which can avoid hitting a human body, indoor tiles, floors and the like, and has a good mute effect. Background Art

[0002] Dumbbells are a type of fitness equipment used to increase muscle strength and endurance. They can be divided into two categories: fixed-weight dumbbells and adjustable-weight dumbbells. Fixed-weight dumbbells have a fixed weight and are usually made of a metal rod and one or two weight plates. Adjustable-weight dumbbells allow users to adjust the weight according to their needs, usually by adding or removing weight plates. Dumbbells are usually made of cast iron, rubber or other durable materials to ensure their weight characteristics and durability.

[0003] In the early days, people would go to professional gyms for fitness. However, with the increasing popularity of fitness activities, many people began to choose to do fitness exercises in their living rooms or balconies. However, most living rooms or balconies are paved with tiles or floors. When using dumbbells, it is easy for the dumbbells to hit the floor tiles, floors, and human bodies. In addition, in high-rise building environments, the sound produced by the dumbbells hitting the ground may also disturb the residents on the lower floors.

[0004] The following prior art was retrieved: a training filling body of CN218740036U, which discloses a dumbbell comprising a main body, two spacers and a filler. The main body is divided by two left and right spacers into two end fillers that are not connected to each other and a closed space portion in the middle. The closed space portion and the filling portions at both ends are separated by a spacer respectively. The closed space portion is the grip of the dumbbell, and the filling portion filled with a filler comprising at least filling particles is the two ends of the dumbbell and a load block.

[0005] According to the document, the fillings at both ends of the dumbbell are weights, usually sand, steel balls, etc., while the grip or filling part is plastic. The dumbbell has the following problems: the fillings at both ends are not connected to each other, so it is necessary to inject filling particles into the fillings at both ends separately in terms of process; at the same time, the weight of the fillings at both ends is inconsistent, which affects the user experience of the dumbbell. Summary of the invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide an inflatable flexible dumbbell.

[0007] The technical solution adopted by the present invention to solve the above technical problems is: an inflatable flexible dumbbell, comprising a first counterweight part, a second counterweight part and a grip part;

[0008] The first weight portion includes a first elastic sac having a first air cavity and a filler in the first air cavity; the second weight portion includes a second elastic sac having a second air cavity and a filler in the second air cavity; the grip portion includes a hard tubular body having a third air cavity and a filler in the third air cavity;

[0009] The hard tubular body, the first elastic sac body and the second elastic sac body are made of plastic; the first end of the hard tubular body borders the inner end of the first elastic sac body, and the first air cavity is separated from the third air cavity by a first separation and combination membrane having a first through hole;

[0010] The second end of the hard tubular body borders the inner end of the second elastic capsule; and the second air cavity is separated from the third air cavity by a second separation and combination membrane having a second through hole;

[0011] The three cavities of the first air cavity, the second air cavity and the third air cavity are connected through the first through hole and the second through hole; the apertures of the first through hole and the second through hole are large enough for fillers to pass through.

[0012] The technical solution adopted by the present invention to solve the above technical problem is: the hard tubular body, the first elastic bladder body and the second elastic bladder body are rotationally molded integral parts;

[0013] The hard tubular body comprises a straight tubular small diameter section in the middle and a first enlarged diameter section and a second enlarged diameter section on both sides;

[0014] The first diameter-enlarged section wraps the inner edge of the first elastic bladder body, and the first diameter-enlarged section and the first elastic bladder body are combined by a first separation and combination membrane;

[0015] The second diameter-enlarged section wraps the inner edge of the second elastic bladder body, and the second diameter-enlarged section and the second elastic bladder body are combined by a second separation and combination membrane;

[0016] A base membrane is arranged between the hard tubular body and the elastic bladder body, and the portion of the hard tubular body bordering the base membrane and the portion of the elastic bladder body bordering the base membrane are both welded to the base membrane to form a separation and bonding membrane.

[0017] The technical solution adopted by the present invention to solve the above technical problems is: the hard tubular body, the first elastic sac, the second elastic sac, the first separating and combining membrane, and the second separating and combining membrane are all made of PVC material; the filler is at least one of sand, iron sand, and steel balls.

[0018] The technical solution adopted by the present invention to solve the above technical problem is: the first diameter expansion section is a first horn section; the second diameter expansion section is a second horn section;

[0019] The first elastic capsule is a first spherical body, and the second elastic capsule is a second spherical body;

[0020] The outer circumference of the first horn section and the outer circumference of the first spherical body, and the outer circumference of the second horn section and the outer circumference of the second spherical body are smoothly transitioned;

[0021] The depth of the first horn section or the second horn section is H, and the radius of the first spherical body or the second spherical body is R; the depth H and the radius R satisfy: 0.2R <H<0.8R。

[0022] The technical solution adopted by the present invention to solve the above technical problems is: an inflatable flexible dumbbell, comprising a first counterweight part, a second counterweight part and a hard grip;

[0023] The first weight portion includes a first elastic sac having a first air cavity; the second weight portion includes a second elastic sac having a second air cavity; the grip portion includes a hard tubular body;

[0024] The hard tubular body, the first elastic sac body and the second elastic sac body are all made of plastic material. The materials at the junction of the hard tubular body and the first elastic sac body and the hard tubular body and the second elastic sac body are fused with each other. The first air cavity and the second air cavity are provided with fillers.

[0025] The preferred technical solution adopted by the present invention to solve the above technical problems is: the hard tubular body includes a straight tubular small diameter section in the middle, a first trumpet section and a second trumpet section; the first elastic capsule is a first spherical body, and the second elastic capsule is a second spherical body; the first trumpet section borders the first spherical body, and the second trumpet section borders the second spherical body;

[0026] The first air cavity is connected to the third air cavity, the second air cavity is connected to the third air cavity, at least one of the first elastic sac and the second elastic sac is provided with an inflation valve core; fillers and gas are provided in the first air cavity, the second air cavity and the third air cavity.

[0027] The preferred technical solution adopted by the present invention to solve the above technical problem is: a method for making an inflatable flexible dumbbell, comprising the following steps:

[0028] Step S1: adding a first plastic raw material into a first mold cavity of a rotational molding mold and sealing a junction between the first mold cavity and a second mold cavity with a first base film; adding a second plastic raw material into a second mold cavity of a rotational molding mold and sealing a junction between the second mold cavity and a third mold cavity with a second base film; adding a first plastic raw material into a third mold cavity of a rotational molding mold;

[0029] Step S2: Turn on the rotational molding equipment, the rotational molding mold continuously rotates and heats the mold cavity, and the plastic raw material in the mold cavity is gradually and evenly coated, melted and adhered to the inner wall of the mold cavity and the surface of the base film under the action of gravity and heat energy, the first plastic raw material in the first mold cavity melts into the first base film, the second plastic raw material in the second mold cavity melts into the first base film and the second base film; the first plastic raw material in the third mold cavity melts into the second base film;

[0030] Step S3: Cooling and shaping to form a molded body having a first elastic bladder body, a hard tubular body, and a second elastic bladder body; the first plastic raw material and the second plastic raw material are respectively welded on both sides of the first base film to form a first separating and combining membrane, and the first elastic bladder body and the hard tubular body are integrally connected to the first separating and combining membrane; the first plastic raw material and the second plastic raw material are respectively welded on both sides of the second base film to form a second separating and combining membrane, and the second elastic bladder body and the hard tubular body are integrally connected to the second separating and combining membrane.

[0031] Step S4: Open the mold and take out the molded body having the hard tubular body, the first elastic bladder body and the second elastic bladder body from the mold.

[0032] The preferred technical solution adopted by the present invention to solve the above technical problem is: it also includes the following steps:

[0033] Step S5: placing the molded body on a tool, using a puncture device to form a single injection hole on the first elastic bladder or the second elastic bladder, and inflating the molded body to a specified size in the tool to form air cavities in the hard tubular body, the first elastic bladder, and the second elastic bladder respectively;

[0034] Step S6: using a puncture device to continuously pass through the inner cavities of the hard tubular body, the first elastic bladder body and the second elastic bladder body through the injection hole to puncture the first separation and combination membrane and the second separation and combination membrane to form a first through hole and a second through hole;

[0035] Step S7: Pour the filler into the first air cavity, the second air cavity and the third air cavity through the injection hole at high pressure, and then insert the inflation valve core into the injection hole to close the injection hole. The first air cavity, the second air cavity and the third air cavity have air gaps so that the fillers in the three cavities can flow to each other.

[0036] The preferred technical solution adopted by the present invention to solve the above technical problem is: it also includes the following steps:

[0037] Step S5: placing the formed body on a tooling, using a puncture device to form injection holes on the first elastic bladder and the second elastic bladder, respectively, the two injection holes are located in a straight line, and further inflating the formed body to a specified size in the tooling to form air cavities in the hard tubular body, the first elastic bladder and the second elastic bladder;

[0038] Step S6: inject the filler into the first air cavity and the second air cavity through the injection holes on both sides at high pressure, and then insert the inflation valve core into the injection hole to close the injection hole.

[0039] The preferred technical solution adopted by the present invention to solve the above technical problem is: the filler is at least one of sand, iron sand and steel balls;

[0040] The first plastic raw material is a low-density PVC material, and the second plastic raw material is a high-density PVC material.

[0041] Compared with the prior art, the advantages of the present invention are: the elastic capsule and the gas contained therein enable the two weight parts of the dumbbell to maintain sufficient weight while also having excellent elasticity. This design not only avoids the risk of the dumbbell accidentally falling and injuring people during use, but also effectively prevents the dumbbell from scratching hard surfaces such as the floor, thereby improving the safety of use and environmental protection.

[0042] Furthermore, the air cavity of the weight part and the air cavity of the grip part are filled with fillers, and the weight of the two weight parts will be more even. Because there is filler in the air cavity of the grip part, the dumbbell has a smaller volume and lower packaging and transportation costs under the premise of equal weight.

[0043] In addition, the three chambers are connected, and the filler can be poured from only one opening or from both ends, which improves the convenience and efficiency of production and reduces manufacturing costs. And as few openings as possible also maximizes the integrity and airtightness of the peripheral wall, ensuring its stability and durability in long-term use. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The present invention will be further described in detail below in conjunction with the accompanying drawings and preferred embodiments, but those skilled in the art will appreciate that these drawings are drawn only for the purpose of explaining the preferred embodiments and therefore should not be used as a limitation on the scope of the present invention. In addition, unless otherwise specified, the drawings are only schematically representing the composition or structure of the described objects and may contain exaggerated displays, and the drawings are not necessarily drawn to scale.

[0045] Figure 1 A three-dimensional diagram of an inflatable flexible dumbbell;

[0046] Figure 2 It is a front view of an inflatable flexible dumbbell;

[0047] Figure 3 is a cross-sectional view of an inflatable flexible dumbbell;

[0048] Figure 4 A cross-sectional view of the plastic parts of the inflatable flexible dumbbell. DETAILED DESCRIPTION

[0049] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It will be appreciated by those skilled in the art that these descriptions are only illustrative and exemplary and should not be construed as limiting the scope of protection of the present invention.

[0050] It should be noted that like reference numerals denote similar items in the following drawings, and thus, once an item is defined in one drawing, it will not be further defined or explained in the subsequent drawings.

[0051] In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "back", "left", "right", "inside", "outside" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or the directions or positional relationships in which the invention product is usually placed when in use, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention. "First" and "second" are only for the purpose of making the description easier to understand, without any other directional meaning, and cannot be used as a limitation on the present invention.

[0052] like Figure 1 As shown, this embodiment provides an inflatable flexible dumbbell, including a hard grip portion 1 in the middle and a first counterweight portion 2 and a second counterweight portion 3 on both sides.

[0053] like Figure 1-4 As shown, the first weight part 2 includes a first elastic bladder 20 having a first air cavity Q1 and a filler in the first air cavity Q1. The second weight part 3 includes a second elastic bladder 30 having a second air cavity Q2 and a filler in the second air cavity Q2.

[0054] Furthermore, if Figure 1-4 As shown, the grip 1 comprises a hard tubular body 10 having a third air cavity Q3 and a filler in the third air cavity Q3. The hard tubular body 10, the first elastic capsule 20 and the second elastic capsule 30 are made of plastic.

[0055] The first end of the hard tubular body 10 borders the inner end of the first elastic sac 20, and the second end of the hard tubular body 10 borders the inner end of the second elastic sac 30. The first air cavity Q1, the second air cavity Q2, and the third air cavity Q3 are connected, and the fillers can flow in the three cavities.

[0056] Although the outer walls of these cavities are made of lightweight plastic, the weight of the plastic alone is difficult to achieve the weighting effect required by traditional dumbbells. To this end, this embodiment achieves a perfect combination of soft and hard materials and ensures a reasonable weighting of the dumbbells by adding a plastic shell with a high internal density filler, so that users can feel moderate resistance during exercise, effectively improving the training effect. Preferably, the filler is at least one of sand, iron sand, and steel balls.

[0057] In this embodiment, the three air cavities are interconnected, which means that only one opening can be opened on the surface of the dumbbell, and the filler can be poured from only one opening. This design not only maximizes the integrity and airtightness of the peripheral wall, but also further enhances the structural strength of the dumbbell, ensuring its stability and durability in long-term use. At the same time, this integrated filling method also greatly improves the convenience and efficiency of production, reduces manufacturing costs, and enables more users to enjoy the fitness fun brought by this innovative product at a more affordable price.

[0058] The grip 1 also adopts a design of a plastic shell with an air cavity and a filler inside, which can avoid the problem of the grip 1 being bent and deformed due to being light in the middle and heavy at both ends, thereby increasing the service life of the dumbbell.

[0059] More importantly, the elastic capsule and the gas contained in the air cavity allow the two weight parts of the dumbbell to maintain sufficient weight while also having excellent elasticity. This design not only avoids the risk of the dumbbell accidentally falling and injuring people during use, but also effectively prevents the dumbbell from scratching hard surfaces such as the floor, thereby improving the safety of use and environmental protection.

[0060] Furthermore, if Figure 3-4 As shown, a first separation and combination membrane 4 having a first through hole K1 is provided between the hard tubular body 10 and the first elastic capsule 20, and the first separation and combination membrane 4 separates the first air cavity Q1 from the third air cavity Q3. A second separation and combination membrane 5 having a second through hole K2 is provided between the hard tubular body 10 and the second elastic capsule 30, and the second separation and combination membrane 5 separates the second air cavity Q2 from the third air cavity Q3. The apertures of the first through hole K1 and the second through hole K2 are sufficient for filling to pass through.

[0061] In this embodiment, the hard tubular body 10, the first elastic capsule 20 and the second elastic capsule 30 are rotationally molded integral parts. A base film is provided between the hard tubular body 10 and the elastic capsule, and the portion of the hard tubular body 10 bordering the base film and the portion of the elastic capsule bordering the base film are melted and integrated with the base film to form a separation and bonding membrane.

[0062] A method for making the inflatable flexible dumbbell provided in this embodiment comprises the following steps:

[0063] Step S1: Add a first plastic raw material into the first mold cavity of the rotational molding mold and seal the junction between the first mold cavity and the second mold cavity with a first base film; add a second plastic raw material into the second mold cavity of the rotational molding mold and seal the junction between the second mold cavity and the third mold cavity with a second base film; add the first plastic raw material into the third mold cavity of the rotational molding mold.

[0064] Step S2: Turn on the rotational molding equipment, the rotational molding mold continuously rotates and heats the mold cavity, and the plastic raw material in the mold cavity is gradually and evenly coated, melted and adhered to the inner wall of the mold cavity and the surface of the base film under the action of gravity and heat energy. The first plastic raw material in the first mold cavity melts into the first base film, the second plastic raw material in the second mold cavity melts into the first base film and the second base film; the first plastic raw material in the third mold cavity melts into the second base film.

[0065] Step S3: Cooling and shaping to form a molded body having a first elastic sac 20, a hard tubular body 10, and a second elastic sac 30; the first base film is respectively welded with the first plastic raw material and the second plastic raw material on both sides to form a first separating and combining membrane 4, and the first elastic sac 20 and the hard tubular body 10 are both integrally connected to the first separating and combining membrane 4; the first plastic raw material and the second plastic raw material are respectively welded with the second base film on both sides to form a second separating and combining membrane 5, and the second elastic sac 30 and the hard tubular body 10 are both integrally connected to the second separating and combining membrane 5.

[0066] Step S4: Open the mold and take out the molded body having the hard tubular body 10, the first elastic bladder body 20 and the second elastic bladder body 30 from the mold.

[0067] Step S5: Place the molded body on a tooling, use a puncture device to form an injection hole on the first elastic bladder 20 or the second elastic bladder 30, and inflate the molded body to a specified size in the tooling to form air cavities in the hard tubular body 10, the first elastic bladder 20 and the second elastic bladder 30 respectively.

[0068] Step S6: using a puncture device to continuously pass through the inner cavities of the hard tubular body 10, the first elastic bladder 20 and the second elastic bladder 30 through the injection hole to puncture the first separation and combination membrane 4 and the second separation and combination membrane 5 to form the first through hole K1 and the second through hole K2.

[0069] Step S7: Pour the filler into the first air cavity Q1, the second air cavity Q2, and the third air cavity Q3 through the injection hole, and then insert the inflation valve core G into the injection hole to close the injection hole. The first air cavity Q1, the second air cavity Q2, and the third air cavity Q3 have air gaps so that the fillers in the three cavities can flow to each other.

[0070] In this embodiment, the puncture device forms injection holes on a straight line on the first elastic bladder 20 and the second elastic bladder 30, thereby achieving double-end injection and improving production efficiency. In addition, an inflation valve core G is formed at both ends of the dumbbell.

[0071] Preferably, the hard tubular body 10, the first elastic capsule 20, the second elastic capsule 30, the first separation and combination membrane 4, and the second separation and combination membrane 5 are all made of PVC material. The first plastic raw material and the second plastic raw material are both paste resins. The first plastic raw material is low-density PVC, and the second plastic raw material is high-density PVC.

[0072] All parts are made of PVC material, which means that during the rotational molding process, each component can reach an ideal melting state under almost the same temperature conditions, ensuring excellent welding effect between the parts.

[0073] In terms of structure, since all components are made of the same material, their thermal expansion coefficients and thermal contraction rates are similar, so that after cooling and solidification, they can form a product with strong integrity and stable structure. In particular, the first separation and combination membrane 4 and the second separation and combination membrane 5 are the key parts connecting the hard tubular body 10 and the elastic capsule body. They melt the materials of the components on both sides onto the same base membrane, so that the three are combined into one to achieve perfect welding, effectively avoiding molding defects caused by material differences, ensuring good welding, and further improving the strength of the junction between the hard tubular body 10 and the elastic capsule body. Therefore, during long-term use, these junctions are not prone to molding defects such as cracking and falling off, thereby greatly extending the service life of the product.

[0074] Structurally, if Figure 1-4 As shown, the hard tubular body 10 includes a straight tubular small diameter section 11 in the middle and a first diameter expansion section 12 and a second diameter expansion section 13 on both sides. The first diameter expansion section 12 wraps the inner edge of the first elastic capsule 20, and the first diameter expansion section 12 and the first elastic capsule 20 are combined through the first separation and combination membrane 4. The second diameter expansion section 13 wraps the inner edge of the second elastic capsule 30, and the second diameter expansion section 13 and the second elastic capsule 30 are combined through the second separation and combination membrane 5. The first diameter expansion section 12 and the second diameter expansion section 13 support the elastic capsule to improve the connection strength between the two.

[0075] Further, the first diameter expansion section 12 is a first horn section. The second diameter expansion section 13 is a second horn section. The first elastic capsule 20 is a first spherical body, and the second elastic capsule 30 is a second spherical body. The outer circumference of the first horn section and the outer circumference of the first spherical body and the outer circumference of the second horn section and the outer circumference of the second spherical body are smoothly transitioned.

[0076] The first diameter-expanding section 12 and the second diameter-expanding section 13 are ingeniously designed as horn sections, whose shapes gradually expand and then seamlessly connect with the spherical elastic bladder. This not only achieves a smooth transition of the pipe diameter but also enables a seamless and smooth transition of the outer peripheral surfaces of different components. This design optimizes the stress distribution functionally, reduces potential stress concentration points caused by sudden shape changes, and also brings aesthetic beauty and neatness to the structure. The smooth and continuous curved lines endow the entire device with a streamlined and elegant appearance, enhancing the visual aesthetic feeling. The smooth transition design makes the touch at each joint delicate, without obvious protrusions or depressions, avoiding scratches or abrasions that may be caused to personnel or objects during use, and also greatly facilitating daily cleaning and maintenance work because it is not easy to accumulate dust, dirt, or residues.

[0077] Furthermore, in the design details of the first horn section and the second horn section, this embodiment also preferably introduces key dimensional parameters - depth H and radius R. The ingenious proportional relationship between these two parameters not only concerns the beauty and smoothness of the structure but also is a direct manifestation of the optimization of the use strength and performance.

[0078] Specifically, the depth of the first horn section or the second horn section is precisely set to H, and the radius of the first spherical body or the second spherical body connected thereto is R. The ideal proportional range between depth H and radius R is: 0.2R < H < 0.8R. The setting of this proportional range aims to balance the structural strength and aesthetics, ensuring the best visual effect and user experience on the premise of meeting the use strength.

[0079] When the depth H is within this proportional range, the joint between the horn section and the spherical body can form a transition surface that is neither too steep nor too gentle. Such a design can not only effectively disperse stress, reduce the stress concentration phenomenon caused by sudden shape changes, thereby improving the fatigue resistance and service life of the entire structure, but also ensure the smooth flow of fluid in the pipeline system, reducing energy consumption and noise.

[0080] An inflatable flexible dumbbell provided by the present invention has been introduced. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the present invention and its core idea. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. An inflatable flexible dumbbell, characterized in that: It includes a first counterweight portion, a second counterweight portion and a grip portion; The first weight portion includes a first elastic sac having a first air cavity and a filler in the first air cavity; the second weight portion includes a second elastic sac having a second air cavity and a filler in the second air cavity; the grip portion includes a hard tubular body having a third air cavity and a filler in the third air cavity; The hard tubular body, the first elastic sac body and the second elastic sac body are made of plastic; the first end of the hard tubular body borders the inner end of the first elastic sac body, and the first air cavity is separated from the third air cavity by a first separation and combination membrane having a first through hole; The second end of the hard tubular body borders the inner end of the second elastic capsule; and the second air cavity is separated from the third air cavity by a second separation and combination membrane having a second through hole; The three cavities of the first air cavity, the second air cavity and the third air cavity are connected through the first through hole and the second through hole; the apertures of the first through hole and the second through hole are large enough for fillers to pass through.

2. An inflatable flexible dumbbell according to claim 1, characterized in that: The hard tubular body, the first elastic bladder body and the second elastic bladder body are rotationally molded integral parts; The hard tubular body comprises a straight tubular small diameter section in the middle and a first enlarged diameter section and a second enlarged diameter section on both sides; The first diameter-enlarged section wraps the inner edge of the first elastic bladder body, and the first diameter-enlarged section and the first elastic bladder body are combined by a first separation and combination membrane; The second diameter-enlarged section wraps the inner edge of the second elastic bladder body, and the second diameter-enlarged section and the second elastic bladder body are combined by a second separation and combination membrane; A base membrane is arranged between the hard tubular body and the elastic bladder body, and the portion of the hard tubular body bordering the base membrane and the portion of the elastic bladder body bordering the base membrane are both welded to the base membrane to form a separation and bonding membrane.

3. The inflatable flexible dumbbell according to claim 1, characterized in that: The hard tubular body, the first elastic sac, the second elastic sac, the first separation and combination membrane, and the second separation and combination membrane are all made of PVC material; the filler is at least one of sand, iron sand, and steel balls.

4. The inflatable flexible dumbbell according to claim 2, characterized in that: The first diameter expansion section is a first horn section; the second diameter expansion section is a second horn section; The first elastic capsule is a first spherical body, and the second elastic capsule is a second spherical body; The outer circumference of the first horn section and the outer circumference of the first spherical body, and the outer circumference of the second horn section and the outer circumference of the second spherical body are smoothly transitioned; The depth of the first horn section or the second horn section is H, and the radius of the first spherical body or the second spherical body is R; the depth H and the radius R satisfy: 0.2R <H<0.8R。 5. An inflatable flexible dumbbell, characterized in that: It includes a first counterweight portion, a second counterweight portion and a hard grip portion; The first weight portion includes a first elastic sac having a first air cavity; the second weight portion includes a second elastic sac having a second air cavity; the grip portion includes a hard tubular body; The hard tubular body, the first elastic sac body and the second elastic sac body are all made of plastic material. The materials at the junction of the hard tubular body and the first elastic sac body and the hard tubular body and the second elastic sac body are fused with each other. The first air cavity and the second air cavity are provided with fillers.

6. The inflatable flexible dumbbell according to claim 5, characterized in that: The hard tubular body includes a straight tube-shaped small diameter section in the middle, a first trumpet section and a second trumpet section; the first elastic capsule is a first spherical body, and the second elastic capsule is a second spherical body; the first trumpet section borders the first spherical body, and the second trumpet section borders the second spherical body; The first air cavity is connected to the third air cavity, the second air cavity is connected to the third air cavity, at least one of the first elastic sac and the second elastic sac is provided with an inflation valve core; fillers and gas are provided in the first air cavity, the second air cavity and the third air cavity.

7. A method for making an inflatable flexible dumbbell according to any one of claims 1 to 4, characterized in that: The steps include: Step S1: adding a first plastic raw material into a first mold cavity of a rotational molding mold and sealing a junction between the first mold cavity and a second mold cavity with a first base film; adding a second plastic raw material into a second mold cavity of a rotational molding mold and sealing a junction between the second mold cavity and a third mold cavity with a second base film; adding a first plastic raw material into a third mold cavity of a rotational molding mold; Step S2: Turn on the rotational molding equipment, the rotational molding mold continuously rotates and heats the mold cavity, and the plastic raw material in the mold cavity is gradually and evenly coated, melted and adhered to the inner wall of the mold cavity and the surface of the base film under the action of gravity and heat energy, the first plastic raw material in the first mold cavity melts into the first base film, the second plastic raw material in the second mold cavity melts into the first base film and the second base film; the first plastic raw material in the third mold cavity melts into the second base film; Step S3: Cooling and shaping to form a molded body having a first elastic bladder body, a hard tubular body, and a second elastic bladder body; the first plastic raw material and the second plastic raw material are respectively welded on both sides of the first base film to form a first separating and combining membrane, and the first elastic bladder body and the hard tubular body are integrally connected to the first separating and combining membrane; the first plastic raw material and the second plastic raw material are respectively welded on both sides of the second base film to form a second separating and combining membrane, and the second elastic bladder body and the hard tubular body are integrally connected to the second separating and combining membrane. Step S4: Open the mold and take out the molded body having the hard tubular body, the first elastic bladder body and the second elastic bladder body from the mold.

8. The method for making an inflatable flexible dumbbell according to claim 7, characterized in that: The following steps are also included: Step S5: placing the molded body on a tool, using a puncture device to form a single injection hole on the first elastic bladder or the second elastic bladder, and inflating the molded body to a specified size in the tool to form air cavities in the hard tubular body, the first elastic bladder, and the second elastic bladder respectively; Step S6: using a puncture device to continuously pass through the inner cavities of the hard tubular body, the first elastic bladder body and the second elastic bladder body through the injection hole to puncture the first separation and combination membrane and the second separation and combination membrane to form a first through hole and a second through hole; Step S7: Pour the filler into the first air cavity, the second air cavity and the third air cavity through the injection hole at high pressure, and then insert the inflation valve core into the injection hole to close the injection hole. The first air cavity, the second air cavity and the third air cavity have air gaps so that the fillers in the three cavities can flow to each other.

9. The method for making an inflatable flexible dumbbell according to claim 7, characterized in that: The following steps are also included: Step S5: placing the formed body on a tooling, using a puncture device to form injection holes on the first elastic bladder and the second elastic bladder, respectively, the two injection holes are located in a straight line, and further inflating the formed body to a specified size in the tooling to form air cavities in the hard tubular body, the first elastic bladder and the second elastic bladder; Step S6: inject the filler into the first air cavity and the second air cavity through the injection holes on both sides at high pressure, and then insert the inflation valve core into the injection hole to close the injection hole.

10. The method for making an inflatable flexible dumbbell according to claim 7, characterized in that: The filler is at least one of sand, iron sand and steel balls; The first plastic raw material is a low-density PVC material, and the second plastic raw material is a high-density PVC material.

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