Needle clamp for sewing machine comprising a needle cooling device

Abstract

A needle clamp (1) for sewing machine (100) is provided. The needle clamp (1) comprises a body (2) at least partially made of a thermally conductive material and having retaining means (3) for constraining at least one needle (10). The needle clamp comprises a thermoelectric cooling device (5) directly or indirectly constrained to a portion of said body (2).

Claims

1. A needle clamp (1) for sewing machine (100), comprising a body (2) at least partially made of a thermally conductive material and having retaining means (3) for constraining at least one needle (10), wherein the needle clamp (1) includes a thermoelectric cooling device (5) directly or indirectly constrained to a portion of said body (2), said thermoelectric cooling device (5) having a hot side (6) and a cold side (7), said cold side (7) being directly or indirectly constrained to said portion of said body (2) allowing heat transfer from said at least one needle (10) to said cold side (7).

2. The needle clamp (1) according to claim 1, wherein said portion of said body (2) on which said thermoelectric cooling device (5) is constrained is an external surface of the body (2).

3. The needle clamp (1) according to claim 1, wherein said thermoelectric cooling device (5) is connected to a control unit for the regulation of said thermoelectric cooling device (5).

4. The needle clamp (1) according to claim 3, wherein said control unit regulates said thermoelectric cooling device (5) according to a feedback loop control.

5. The needle clamp (1) according to claim 1, wherein said retaining means (3) comprise a recessed seat (11) in said body (2) for receiving at least part of said needle (10) therein, said seat (11) having a longitudinal extension according to an axis (A-A), said thermoelectric cooling device (5) extending on a portion of said body (2) of an angle (a) comprised between 0 and 360 in a plane perpendicular to said axis (A-A).

6. The needle clamp (1) according to claim 5, wherein said angle (a) is between 0 and 270.

7. The needle clamp (1) according to claim 1, wherein said thermoelectric cooling device (5) comprises at least one Peltier cell.

8. The needle clamp (1) according to claim 1, wherein said thermoelectric cooling device (5) is indirectly constrained to said portion of said body (2) by the interposition of a thermal conductive layer (8).

9. The needle clamp (1) according to claim 8, wherein said thermal conductive layer (8) is an adhesive thermal paste.

10. A sewing machine (100) comprising at least one needle clamp (1), said needle clamp comprising a body (2) at least partially made of a thermally conductive material and having retaining means (3) for constraining at least one needle (10), wherein the needle clamp (1) includes a thermoelectric cooling device (5) directly or indirectly constrained to a portion of said body (2), wherein said thermoelectric cooling device (5) has a hot side (6) and a cold side (7), said cold side (7) being directly or indirectly constrained to said portion of said body (2) allowing heat transfer from said at least one needle (10) to said cold side (7).

11. The sewing machine (100) according to claim 10, wherein said sewing machine (100) has an electric circuit connected to an electric power source, said thermoelectric cooling device (5) is connected to said electric circuit of said sewing machine (100).

12. A method of cooling a needle (10) retained by a needle clamp (1) for a sewing machine (100), said needle clamp (1) comprising a body (2) at least partially made of a thermally conductive material and having retaining means (3) for constraining at least one needle (10), said method comprising the steps of: (a) constraining directly or indirectly a thermoelectric cooling device (5) to a portion of said body (2); (b) regulating said thermoelectric cooling device (5) to control heat transfer from said needle clamp; and (c) providing electric power to said thermoelectric cooling device (5).

13. The method according to claim 12, wherein in said step (a) said thermoelectric cooling device (5) is indirectly constrained to said portion of said body (2) with a thermal conductive layer (8).

14. The method according to claim 12, wherein said sewing machine (100) has an electric circuit connected to an electric power source and said thermoelectric cooling device (5) is connected to said electric circuit of said sewing machine (100).

15. The sewing machine (100) according to claim 10, wherein said portion of said body (2) to which said thermoelectric cooling device (5) is constrained, is an external surface of the body (2).

16. The sewing machine (100) according to claim 10, wherein said thermoelectric cooling device (5) is connected to a control unit for the regulation of said thermoelectric cooling device (5).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further aspects and advantages of the present invention will be discussed more in detail with reference to the enclosed drawings, given by way of non-limiting example, wherein:

(2) FIG. 1 is a front view of the needle clamp for sewing machine according to an embodiment of the present invention;

(3) FIG. 2a is a top view of the needle clamp before constraining a thermoelectric cooling device to a portion of the body of the needle clamp, according to an embodiment of the present invention; and

(4) FIG. 2b is a top view of the needle clamp after constraining a thermoelectric cooling device to a portion of the body of the needle clamp, according to an embodiment of the present invention.

DETAILED DESCRIPTION

(5) As for example shown in FIGS. 1-2, the needle clamp 1 according to the present invention, comprises a body 2 constrained to an arm 12 of a sewing machine. The needle clamp 1 is configured to retain a needle 10 during sewing operations. The needle 10 is retained in the needle clamp 1 by accommodating the needle 10 in a recessed seat 11 provided in the body 2 of the needle clamp 1. When the needle 10 is positioned in the recessed seat 11, retaining means 3 intended to constrain the needle 1 in a removable manner (i.e. reversibly) to the needle clamp 2.

(6) The retaining means 3 also allow to remove the needle 1 from the recessed seat 11 of the needle clamp 1 in case of maintenance or when it is necessary to replace a used needle with a new needle, or when a needle with different characteristics has to be used according to the fabric to be sewn.

(7) According to a possible embodiment, as for example shown in FIG. 1, retaining means 3 comprises a clamping pin and a knob 4 that when screwed in a correspondent threated hole, reversibly constrain the clamping pin and the needle 1 in the recessed seat 11 of the body 2 of the needle clamp 1. According to other embodiments not shown, the retaining means can be provided with different configuration with respect to that disclosed above and shown in the figures, provided that the needle can be retained in the needle clamp.

(8) The recessed seat 11 accommodating the needle 10 in the body 2 of the needle clamp 1 is preferably provided with a longitudinal extension according to an axis A-A. The axis A-A extends in the same direction of the longitudinal axis of the needle 10, when the needle 10 is accommodated in the recessed seat 11 of the body 2 of the needle clamp 1.

(9) The body 2 of the needle clamp 1 is at least partially made of a thermally conductive material. For example, a conductive material used for the body 2 of the needle clamp 1 is a metallic material. The retaining means 3 for retaining the needle in the recessed seat 11 in the body 2 of the needle clamp 1 is at least partially made of a thermally conductive material, as an example a metallic material.

(10) During sewing operations, the arm 12, the body 2 of the needle clamp 1 and the needle 10 move along the axis A-A. When the needle 10 penetrates the fabric, the friction between the sewing needle 10 and the fabric, generates the overheating of the needle 10. In fast sewing machines, the needle overheating can result in a severe increment in temperature of the needle 10, causing the damage of the seam, of the fabric, of the needle, or a combination thereof.

(11) The needle clamp 1 according to the present invention, comprises a thermoelectric cooling device 5 constrained to the body 2 of the needle clamp 1.

(12) As already mentioned above, according to an embodiment, the thermoelectric cooling device 5 is a device able to transfer heat from one side of the device, to the other side, by means of electric energy. The effect that correlates a difference in voltage to a difference in temperature, also known with the term thermoelectric effect, is obtained by a device comprising two types of semiconductors placed thermally in parallel and electrically in series. According to an embodiment, when electric current flows in the device, a difference in temperature between the two thermally parallel sides of the semiconductors is generated, resulting in a difference in temperature between the two sides of the device. Thermoelectric devices can be used both as cooler devices and as thermoelectric generator. Thermoelectric devices, known as Peltier cells, applies a different voltage by electric energy to obtain a difference in temperature between the two sides of the device. Thermoelectric devices, known as Seebeck cells, convert a difference in temperature between two sides of the device in electricity.

(13) As for example shown in FIGS. 1, 2a,b, the thermoelectric cooling device 5, such as at least one Peltier cell, comprises a hot side 6 and a cold side 7. The thermoelectric effect is used to transfer heat from the needle clamp to a first side of the device, e.g. a cold side 7, to a second side 6, e.g. a hot side 6. According to an embodiment, electric power can be used to generate, by thermoelectric effect, a difference in temperature between the two sides 6,7 of the thermoelectric device 5, thus allowing heat transfer from the needle clamp.

(14) The thermoelectric cooling device 5, e.g. a Peltier cell, is constrained to a portion of the body 2 of the needle clamp 1 and, more in detail, the thermoelectric cooling device 5 is constrained to a portion of the external surface of the body 2. The thermoelectric cooling device 5 extends on a portion of said body 2 of an angle comprised between 0 and 360, preferably between 0 and 270, in a plane perpendicular to the axis A-A that extends along the longitudinal extension of the recessed seat 11 and the longitudinal axis of the needle 10.

(15) The thermoelectric cooling device 5 is constrained to the body 2 of the needle clamp 1 directly or indirectly.

(16) According to an embodiment of the present invention, the cooling device 5 is directly constrained to the external surface of the needle clamp 1 by contacting the first side 7 of the cooling device 5 with a portion of the external surface of the body 2 of the needle clamp 1. Retaining means for retaining the cooling device on the body 2 in a direct constraint may comprise screws, rivets or protruding elements protruding from the external surface of the body 2 suitable to interface directly the cooling device 5, the cooling device 5 and the body 2 of the needle clamp 1 for example by interlocking the cooling device 5 in said protruding elements.

(17) According to another possible embodiment of the present invention, the cooling device 5 is indirectly constrained to the external surface of the needle clamp 1 by interposing an additional layer between the first side 7 of the cooling device 5 and the external surface of the body 2 of the needle clamp 1. More in detail, according to an aspect of the invention, the additional layer is a thermal conductive layer 8, such as a thermal past. Advantageously, the additional thermal conductive layer is an adhesive layer that constrains the cooling device 5 on the external surface of the body 2 of the needle clamp 1.

(18) According to this embodiment, an adhesive thermal paste adheres from one side to the cold side 7 of the cooling device 5 and on the other side to the external surface of the body 2 of the needle clamp 1.

(19) The thermoelectric cooling device 5 is thermally in contact with the needle 10 since heat flows from the needle 10 to the cooling device 5, preferably by conduction.

(20) According to an embodiment, heat flows from the needle 10 through the recessed seat 11 of the body 2 of the needle clamp 1, to the body 2 of the needle clamp 1, to the cold side 7 of the cooling device 5. According to another embodiment, heat flows from the needle 10 through the recessed seat 11 of the body 2 of the needle clamp 1, to the body 2 of the needle clamp 1, to the adhesive thermal paste 8, to the cold side 7 of the cooling device 5.

(21) Advantageously, according to an embodiment of the present invention, the cooling power of the thermoelectric cooling device 5 can be controlled by the electric power supplied to the cooling device 5. The regulation of the electric power supplied to the cooling device 5 results in a regulation of the temperature of the cold side 7 of the cooling device 5. Moreover, since the intensity of the heat flow from the overheated needle to the cold side 7 of the cooling device, is a function of the difference in temperature between the needle 10 and the cold side 7 of the cooling device 5, the cooling effect of the needle 10 and the temperature of the needle 10 can be controlled by the regulation of the electric power supplied to the cooling device 5.

(22) As already mentioned above, even if not shown in the attached figures, a heat dissipation element (e.g. heat sink) can be provided and preferably constrained to the second (external) side 6 of the thermoelectric device to increase heat transfer to the external environment.

(23) According to a possible embodiment, even if not shown in the figures, at least one temperature sensor, e.g. a thermocouple, can be provided to detect temperature of needle and/or of the needle clamp. The generated temperature sensor value can be used to control the thermoelectric device.

(24) It has to be noted that according to different possible embodiments, the thermoelectric device and thus the heat transfer from the needle clamp to the external environment can be carried out manually, e.g. by an operator that activates/deactivates the thermoelectric device or that regulates the electric current provided to the thermoelectric device, e.g. to a Peltier cell.

(25) However, it has to be also noted that the heat transfer can be controlled automatically, for example by a feedback loop control of the thermoelectric device. According to this embodiment, even not shown in the attached figures, a PID controller or any other negative feedback loop control device can control the current through the thermoelectric device to alter the pumped heat (transferred heat) from the needle clamp outwards.

(26) The regulation of the thermoelectric device can be advantageously carried out automatically e.g. by regulating the electric current provided to the thermoelectric device, e.g. to a Peltier cell. According to a possible embodiment, the sewing machine 100 has an electric circuit connected to an electric power source, and advantageously, the thermoelectric cooling device 5 is connected to said electric circuit of said sewing machine 100. In other words, the thermoelectric cooling device 5 uses the same electric power source of the sewing machine 100 for cooling the cold side 7 of the cooling device 5. In this way, it is possible to use just one electric power source reducing the complexity and the encumbrance of a further electric power source different from the power source of the sewing machine 100.

(27) The present invention also discloses a method for cooling a needle 10 retained by a needle clamp 1 for a sewing machine 100, comprising the step of constraining directly or indirectly a thermoelectric cooling device 5 to a portion of said body 2, and the step of regulating the thermoelectric cooling device 5.

(28) According to an embodiment, the method also comprise the step of providing electric power to said thermoelectric cooling device 5, e.g. a Peltier cell.

(29) The thermoelectric cooling device 5 is indirectly constrained to a portion of the external surface of said body 2 according to step a) of the method according to the present invention, as shown in FIG. 2a,b. FIG. 2a shows a top view of the needle clamp 1 and three external free surfaces of the body 2 of the needle clamp 1. According to an embodiment, the thermoelectric cooling device 5 comprises three Peltier cells, each comprising a hot side 6 and a cold side 7. An adhesive thermal paste 8 is adhered on one side on the cold side 7 of the Peltier cells, and on the other side is suitable to adhere on a portion of the external surfaces of the body 2 of the needle clamp 1. FIG. 2b shows the same view of the needle clamp 1 and the thermoelectric cooling device 5 of FIG. 2a, after the adhesion of the Peltier cells on the portion of the external surfaces of the body 2 of the needle clamp 1, according to the present invention.

(30) By providing electric power to the thermoelectric device 5, according to the possible step of the method, the cold side 7 of the Peltier cells decrease in temperature according to the thermoelectric effect. As long as the temperature of the cold side 7 of the thermoelectric device 5 is lower than the temperature of the needle clamp 1 and of the needle 10 overheated by friction during sewing operations, an heat flow occurs from the needle 10 to the thermoelectric device 5, and thus to the second side 6 (external side) of the thermoelectric device and thus to the external ambient.